Darwin’s “Damned land”: A paleo(neo)botanist’s paradise

Alejandra María Gandolfo, School of Integrative Plant Science, Cornell University

mag4@corenell.edu

Patagonia, Darwin’s Damned land, comprises the last 1000 miles of South America. This region is characterized by many different plant associations determined by abiotic and biotic factors. Major geotectonic and climatic changes that affected Patagonia include its separation from Antarctica, the establishment of the Circumpolar and Humboldt Currents, the Pacific and Atlantic ingressions, the uplift of the Andes, and the development of the “Patagonian Arid Diagonal”. This complex tectonic activity coupled with intense climatic changes turned Patagonia into a natural floristic laboratory in which examples of biogeographic and evolutionary processes preserved in the fossil record help us to understand the development of modern plant distributions. Research on fossils from Patagonian formations that range from the upper Cretaceous (80 mya) to the end of the Paleogene (23 mya) coupled with those from the Antarctic Peninsula provides critical data for understanding the origin and evolution of floras in the Southern Hemisphere. In this contribution, I will present iconic examples of these evolutionary processes that occurred in Patagonia in relation to the geological and climatic variables that contributed modern plant distribution in the area.

‘Out of this world’: The deep-time origins of modern Neotropical Rainforests Modern Neotropical rainforests are hotspots for global biodiversity and biological research.

Mónica R. Carvalho, Smithsonian Tropical Reserch Institute

moccada@gmail.com

Countless explorers, naturalists, and scientists have been historically drawn by the allure of outstanding diversity and complexity of species interactions, and more recently by the fundamental role that rainforests play in global climate and biochemical cycles. The evolution of these tropical systems in deep time has nonetheless remained elusive, mainly owing to the difficulty of assessing the plant fossil record in areas with deep soils and naturally covered by thick vegetation.Over the past decades, paleobotanical exploration in Colombia has revealed thousands of fossil leaves and pollen samples that span the Maastrichtian and Paleocene (72 – 56 mya). This record provides a unique insight into the long-lasting effects of the end-Cretaceous extinction event on tropical vegetation. In this contribution, I will explore extinction and recovery rates, plant community turnover, and changes in forest types that were related to the end-Cretaceous extinction and that had profound ecological implications on rainforest function. The plant fossil record from tropical South America shows that the end-Cretaceous event triggered a long interval of low plant diversity in the Neotropics and the evolutionary assembly of today’s most diverse terrestrial ecosystem.

Exploring zosterophyll relationships under a broader sampling of character space.

Megan Nibbelink (Humboldt State University), Alexandru Tomescu (Humboldt State University)

men134@humboldt.edu

Important constituents of Siluro-Devonian floras, zosterophylls gave rise to the lycophytes. To address their relationships, we analyzed a matrix of 40 characters and 20 genera that span the Lochkovian-Eifelian interval, maximizing sampling of anatomy. We used phylogenetic and phenetic analyses to (1) explore relationships among zosterophylls under broader character sampling; (2) assess the influence of tree rooting, taxon sampling, and morphological vs anatomical characters on the stability of relationships; (3) compare phylogenetic and phenetic methods in terms of relationships recovered. Phenetic analyses (clustering) showed high sensitivity to taxon sampling; recovered Huia+Nothia most similar to each other, consistent with the phylogenetic results; and provided support for placement of Renalia among zosterophylls. Phylogenetic analyses demonstrated that taxon sampling and tree rooting significantly influence resolution. Trees rooted with Renalia showed higher resolution than trees rooted with Psilophyton. Inclusion of Sengelia, an early lycopsid, and exclusion of Stolbergia (taxon with highest percentage of missing data), also yielded higher resolution. We consistently recovered three clades: Huia+Nothia sister to the rest of the ingroup, wherein two clades correspond to the previously recovered sawdonialean and “nonterminate” groups. Inclusion of Sengelia in the latter clade supports earlier ideas that the lycopsid ancestor had nonterminate fertile axes. Whereas exclusion of morphological characters diminished phylogenetic resolution, morphology-only analyses recovered a tree that differs from that obtained using morphology+anatomy in the membership of sawdonialean and “nonterminate” clades. These differences highlight the importance of broader sampling of the morphological character space. Because both anatomy and morphology are part of the evolutionary history of a species, relationships recovered using both morphological and anatomical characters are more likely to reflect natural evolutionary relationships. Thus, breadth of character sampling and not the amount of phylogenetic resolution should be the primary criterion for selecting between alternative hypotheses of relationships.

Ecological (dis)similarity between Pennsylvanian coal floras across space and time

Sydney Booth, Dept. of Integrative Biology, UC Berkeley; Henry Thomas, Dept. of Integrative Biology, UC Berkeley; Ivo Duijnstee, Dept. of Integrative Biology and UCMP, UC Berkeley; Benjamin Muddiman, Dept. of Integrative Biology and UCMP, UC Berkeley

sydney_booth@berkeley.edu

The Phillips Coal Ball Collection (PCBC) is one of the largest paleobotanical datasets in existence, representing 50,000 coal balls collected from Pennsylvanian coal localities in North America, Europe, Asia, and North Africa. These coals represent the remains of equatorial peat forests, dominated by lycopods, ferns, pteridosperms, sphenopsids, and cordaites. The collection spans the Carboniferous Rainforest Collapse, a floral turnover event at the end of the Middle Pennsylvanian, where lycopod-dominated swamp forests gave way to fern-dominated communities. Over 800,000 square-centimeters of PCBC coal ball peels have been analyzed microscopically, reflecting the taxonomic composition of each coal. This dataset, which has recently been re-digitized, makes possible large-scale analysis of Pennsylvanian coal ball community composition and change. We analyzed the PCBC dataset, testing for correlation between spatial and temporal distance and difference in floral composition between 17 coal seams, each representing a glacial interval. These coals span the breadth of the Pennsylvanian and primarily hail from the Illinois Basin. We calculated Chao and Bray-Curtis values, two commonly used metrics in ecological statistics, between pairs of coals to quantify ecological dissimilarity. We mapped reconstructed paleocoordinates of each coal locality, calculated great circle distances, and charted the taxonomic composition of each coal to look for spatial patterns in community composition. We found no clear linear correlation between ecological dissimilarity and spatial distance, nor did we find any patterns specific to only latitude or longitude; we did, however, find a positive correlation between dissimilarity and relative temporal distance for both indices. Pairwise comparisons of coals in different North American stages demonstrated distinct trends, which differed based on the boundary in question; comparisons that cross from the Morrowan or Atokan to the Desmoinesian have lower dissimilarity on average than comparisons that cross between the Desmoinesian (Middle Pennsylvanian) and the Missourian/Virgilian (Late Pennsylvanian). The higher dissimilarity values for comparisons across the Middle-Late Pennsyvlanian boundary reflect the floral turnover of the Carboniferous Rainforest Collapse.

Early Devonian evidence for modular assembly of the regulatory toolkit for secondary growth.

Kelly C. Pfeiler, University of Kansas; Alexandru M.F. Tomescu, Humboldt State University

pfeiler@ku.edu

Recent plant fossil discoveries have uncovered previously unrecognized anatomical diversity among Early Devonian (390 Ma) euphyllophytes. These new plants inform hypotheses of relationships and reveal unexpected complexity in the early stages of the first vascular plant radiation. A prime character that contributes to plant structural diversity and complexity is secondary growth from a vascular cambium, a process that produces secondary xylem (wood). Vascular cambial growth is controlled by a set of interacting but independent regulatory modules, which, in different combinations, result in different modes of secondary growth. The activity of some of these modules can be recognized in extant and extinct plants based on key structural fingerprints, such as radially aligned tracheids, presence of rays (or, more generally, of a radially polarized tissue component), and multiplicative (anticlinal) divisions. The recognition of such fingerprints in recently discovered Early Devonian euphyllophytes demonstrates that secondary growth originated and diversified rapidly in the Early Devonian and lends support to the modular view of cambial growth regulation. We describe a new Early Devonian plant that adds yet another type to the growing list of modes of secondary growth documented in the Early Devonian. This new plant and the other euphyllophytes that mark the earliest occurrences of secondary growth possess structural fingerprints that illustrate different combinations of regulatory modules acting in secondary growth. Considered together, these plants demonstrate different degrees of canalization of regulatory modules controlling secondary growth and their mosaic pattern of expression in coeval Early Devonian tracheophytes.

New complexity in arborescent lycopsid cambial dynamics.

Michael, D'Antonio, Geological Sciences - Stanford University

mdantoni@stanford.edu

The vascular cambium of late Paleozoic arborescent lycopsids is enigmatic and elusive, having never been positively identified in the fossil record. Our understanding of this meristem, therefore, comes almost entirely from wood anatomy, commonly preserved in “coal ball” calcium carbonate concretions. In a seminal paper, Michael Cichan (1985) hypothesized that, as lycopsids produced wood to the inside of the cambium, the cambium itself expanded to keep pace with the wood periphery mainly via expansion of the diameter of the fusiform initials, rather than via multiplicative anticlinal divisions of the fusiform initials. This manifested as progressive outwards expansion of wood tracheid diameters within cell files rather than the appearance of new cell files within the wood. This hypothesis is consistent with the majority of the arborescent lycopsid body plan—branches, distal portions of the trunk, and the stigmarian rooting system. However, our understanding of the most proximal portion of lycopsid trunks has only come into focus since the publication of Cichan (1985). Here, I revisit the one known proximal arborescent lycopsid trunk stele, a specimen of Diaphorodendron vasculare that possesses a minute protostele composed of just a handful of primary xylem tracheids surrounded by wood over 1.5 cm thick. In addition to the gradual broadening of existing cambial initials previously identified by Cichan, this specimen also shows that the cambium expanded in circumference in two other ways that involved the creation of new initials as evidenced by new persistent tracheid files in the wood: 1. multiplicative anticlinal divisions, and 2: meristematic activity within patches of interrupted wood. These findings are complementary with those of Cichan (1985) while also expanding the known toolkit of developmental dynamics at the base of the tree, showing that the arborescent lycopsid cambium was more complex than previously thought.

The Permian (sub)arborescent lycopsids from Gondwana: what we do and do not know about some of them.

Rafael Spiekermann, Senckenberg Forschungsinstitut und Naturmuseum, Frankfurt am Main, Germany; André Jasper, Programa de Pós-Graduação em Ambiente e Desenvolvimento, Universidade do Vale do Taquari – Univates, Lajeado, Brazil; Dieter Uhl, Senckenberg Forschungsinstitut und Naturmuseum, Frankfurt am Main, Germany

rafael.spiekermann@senckenberg.de

Arborescent to subarborescent lycopsids were important components of the Permian floras from Gondwana, especially in the western part of this paleocontinent. Most lycopsid macrofossils have been included in the genera Brasilodendron, Azaniadendron, Cyclodendron, and Lycopodiopsis. The genus Brasilodendron comprises in situ corm-like stumps, and impressions and compressions of unbranched vegetative axes, which bear attached leaves or are covered in fusiform leaf cushions lacking leaf scars. Nothing is known about its reproductive organs, albeit remains of this taxon usually occur in association with abundant megaspores. Azaniadendron and Cyclodendron are based on vegetative and fertile axes preserved either as impressions or compressions, but their rooting system remains unknown. Both were heterosporous with sporangia arranged in fertile zones rather than compact cones. The axes of Azaniadendron are covered in cushions of variable shape, bearing a not always obvious leaf scar, whereas Cyclodendron axes are unbranched or dichotomizing and generally covered in leaf scars and/or leaf traces. Lycopodiopsis was originally based on anatomically preserved axes with a discontinuous vascular cylinder. Currently, impressions of vegetative axes have been included in this taxon as well. It is interpreted as a lycopsid that grew as a branched pole, and its reproductive structures and roots remain unknown. These Gondwanan taxa have been traditionally distinguished from the Euramerican Carboniferous arborescent forms by the absence of a ligule and parichnos, but do they all really lack ligule and were part of a lineage of eligulate arborescent to subarborescent lycopsids? So far, little is known about these southern plants, and currently, we are reinvestigating their fossil record to clarify their taxonomy and spatial-temporal distribution, as well as provide new insights on their growth architecture, ecology, and systematic position within Lycopsida.

New data on glomeromycete spores in the Lower Devonian (Emsian; c. 400 Ma) of Gaspé (Quebec, Canada).

Madison Lalica, Humboldt State University Biological Sciences; Mihai Tomescu Humboldt State University Biological Sciences

mal182@humboldt.edu

Fossil assemblages preserved in fluvial-coastal Emsian strata of the Battery Point Formation of Gaspé Bay (Quebec, Canada) are among the most diverse occurrences of Early Devonian permineralized plants worldwide. The plants host fungal material, including spores that show affinities to the Glomeromycotina. A survey of over 200 specimens within 12 trimerophyte axes, reveals the presence spores (90-240 μm) that may represent a new species of Glomites. These spores exhibit four wall layers (when well preserved), of which two are more resilient: a thick, dark layer to the outside of a thin, membranous layer. The spores are globose/ovoid and have subtending hyphae with varying types of occlusion. Circumstantial evidence suggest that the spores were metabolically active within their plant hosts at the time of fossilization and that the plants were alive at the time of infection: hyphae and vesicles, indicative of metabolically active fungi co-occur with the spores; when well preserved, the tissues of some host plant axes are notably affected in the vicinity of the spores; within individual axes, spores show varying levels of preservation, consistent with continued spore development (and subsequent breakdown), which implies longer-term interactions that are more likely sustained in living plant tissues. In light of comparisons with other fossil glomeromycetes and considering the life history traits of living glomeromycetes, our observations of the Battery Point Formation material suggest that the fungi producing the spores had an endomycorrhizal role. This occurrence is one of very few reports of fungi in the Battery Point Formation. These fungal fossils represent the only Early Devonian glomeromycete occurrence documented outside the hot spring deposits of the Rhynie chert. The presence of glomeromycetes in plants of typical fluvial-coastal environments and their putative mycorrhizal role, suggest that like their extant counterparts, glomeromycetes were relatively ubiquitous symbionts of tracheophytes, by the Early Devonian.

Early Mississippian microarthropod herbivory on laminate leaves.

Michael P. Donovan, Department of Paleobotany and Paleoecology, Cleveland Museum of Natural History; Mark A. Gorman, Denver Museum of Nature and Science; Michael T. Dunn, Department of Agriculture, Biology, and Health Science, Cameron University; Sandra R. Schachat, Stanford University

mdonovan@cmnh.org

Small herbivorous arthropods began feeding on vascular plants and liverworts during the Early and Middle Devonian as evidenced by rare, minute feeding marks on fossil plants. By the end of the Mississippian, larger external foliage feeding damage, presumably made by insects, occurred on laminate leaves, but the evolution of herbivory between these two phases is not understood. Here, we report microarthropod damage on laminate leaves of the probable pteridosperms, Genselia compacta and Charbeckia macrophylla, from early Mississippian (Tournaisian) deposits of the Price Formation in West Virginia and Virginia, USA. We assessed the diversity and frequency of arthropod herbivory, as well as the surface area of tissue removed from the most well sampled flora (Alta, West Virginia). We found eight damage types (DTs), including six external foliage feeding (hole feeding, margin feeding, surface feeding) and two possible gall or piercing and sucking DTs. Across functional feeding groups, arthropod damage is small, typically <1-2 mm in diameter, suggesting microarthropods were still the dominant herbivores in the Tournaisian. The morphology of the external foliage feeding damage is consistent with herbivory made by insects with dicondylous, incisiform mandibles, although other arthropods, such as diplopods, cannot be completely discounted as culprits. Tissue consumption was minor, with only 0.05% of the surface area of the laminate plant species removed. Feeding damage on the Price Formation floras pushes back the origin of herbivory on laminate leaves by 16 million years and highlights the importance of pteridosperms in the early evolution of arthropod herbivory. In addition, our results reveal previously unrecognized feeding behaviors by terrestrial arthropods, possibly insects, during the Hexapod Gap, a 62 million year gap (Late Devonian-Mississippian) in the insect body fossil record.

The Early Cretaceous vegetation of central Alberta as a food source for the armoured dinosaur Borealopelta markmitchelli.

Jessica Kalyniuk, Brandon University; David Greenwood, Brandon University; James Basinger, University of Saskatchewan; Caleb Brown, Royal Tyrrell Museum of Palaeontology; Donald Henderson, Royal Tyrrell Museum of Palaeontology; & Cathy Greenwood, Brandon University

jekalyniuk@gmail.com

Large herbivores act as keystone species today, as they did in the Cretaceous. Despite their significance in Cretaceous ecosystems, what herbivorous dinosaurs ate is unclear. Borealopelta markmitchelli is an exceptionally well-preserved herbivorous, armoured dinosaur (Ornithischia; Nodosauridae) from the marine Lower Albian Clearwater Formation of northern Alberta. A distinct mass within the abdominal cavity, containing plant tissue fragments and gastroliths, is interpreted as stomach contents (a cololite). A large portion of the cololite mesoflora is leaf tissue (87.6%), including sporangia, leaf cross-sections and leaf epidermis ± cuticle, with a smaller presence of stems, wood, and charcoal. The leaf fraction is dominated by leptosporangiate ferns (Subclass Polypodiidae) based on sporangia with a well-defined annulus. A minor fraction of cycad–cycadophyte (2.7%) and trace conifer foliage was also present based on diagnostic leaf anatomy. The contemporaneous terrestrial Lower Albian Gates Formation (Grande Cache Member) macroflora of central Alberta shows that local vegetation available for B. markmitchelli was rich in ferns (e.g., Cladophlebis, Coniopteris, Gleichenites). Gymnosperms, such as Caytoniales (e.g., Sagenopteris), conifers (e.g., Pityophyllum, Elatides), and ginkgophytes (e.g., Ginkgo, Ginkgoites) were abundant. Among this macroflora, angiosperms, Taeniopteris, cycads (Cycadales, e.g., Ctenis), and Equisetum were rare, while cycadophytes (Bennettitales, e.g., Pseudocycas) were common. When comparing the macroflora and cololite mesoflora, these data suggest that B. markmitchelli was feeding on the most common vegetation present – ferns. The rarity of cycad–cycadophyte and conifer leaves in the cololite, versus richness in the Gates Formation, indicates that these plants were not the primary target. Additionally, significant presence of charcoal (5.7%) in the cololite may indicate dietary utilization of a recently burned landscape undergoing fern succession—a behaviour also seen among modern large herbivores. The data presented here is direct evidence of diet and represents the most well-supported and detailed description of herbivorous dinosaur diet to date.

An Early Cretaceous Fossil Seed in Three Modes of Preservation from Central Mongolia and Inner Mongolia, China.

Maya, Bickner, Chicago Botanic Garden and Northwestern University; Fabiany, Herrera, Chicago Botanic Garden; Patrick, Herendeen, Chicago Botanic Garden

mayabickner2021@u.northwestern.edu

An anatomically preserved gymnosperm seed has been recovered from the Early Cretaceous Tevshiin Govi and Tugrug Formations in Mongolia and the Zhahanaoer Formation in Inner Mongolia, China. The specimens are very common in the floras and are preserved in three modes: lignite mesofossils, permineralized fossils, and macrofossils. The seeds are 5.7-9.8 mm long, 5.0-7.7 mm wide, and are elliptical or circular in longitudinal section. The integument has three parts or valves, defined by sutures that extend through the integument in the major plane of section, giving the seeds radial symmetry. The seeds possess 12 to 16 prominent longitudinally oriented ribs on the integument that rise from a central attachment scar. The ribs extend toward the apex and terminate before reaching a short micropylar region. The micropyle extends above the seed body and is absent in specimens where the integument valves are split at the apex. The integument is three-layered. The outer layer of the integument is a thin palisade of rounded thick-walled cells. The middle layer of the integument is thickest and forms the bulk of the ribs. The middle layer is comprised of variable-sized thick-walled isodiametric cells aligned perpendicular to the outer layer of the integument in rib furrows, becoming parallel within ribs. The innermost integument layer is comprised of thin-walled, elongated cells aligned with the seed circumference. Remnants of an epidermis are present on the integument's surface. Specimens were studied using a combination of traditional anatomical sectioning and synchrotron radiation X-ray micro-tomography allowing us to incorporate the three modes of preservation into one species description. These analyses suggest the seeds had a distinct mode of germination via splitting of the trimerous integument. This newly recognized seed represents a prominent gymnosperm that grew in and near peat swamps in central Mongolia and northern China landscapes during the Early Cretaceous.

Early Cretaceous abietoid Pinaceae from Mongolia and the history of seed scale shedding.

Fabiany, Herrera, Chicago Botanic Garden; Gongle, Shi, Nanjing Institute of Geology and Palaeontology; Maya A., Bickner, Chicago Botanic Garden; Niiden, Ichinnorov, Institute of Paleontology, Mongolian Academy of Sciences, Ulaanbaatar; Andrew B., Leslie, Stanford University; Peter R., Crane, Oak Spring Garden Foundation; Patrick S., Herendeen, Chicago Botanic Garden

fherrera@chicagobotanic.org

Seed cones of extant Pinaceae exhibit two mechanisms of seed release. In ‘flexers’ the cone scales remain attached to the central axis, while flexing and separating from each other to release the seeds. In ‘shedders’ scales are shed from the axis, with the seeds either remaining attached to the scale or becoming detached. The early fossil history of Pinaceae from the Jurassic to Early Cretaceous is dominated by flexing seed cones, while the systematic information provided by shedding fossil cones has been overlooked and rarely integrated with data based on compression and permineralized specimens. We describe the earliest and best–documented evidence of a “shedder” seed cone from the Aptian–Albian of Mongolia. The fossils come from a lignite deposit at the Tevshiin Govi locality. The new fossils were compared to material of extant Pinaceae using CT scans and morphological comparisons. Lepidocasus mellonae gen. et sp. nov., is characterized by a seed cone that disarticulated at maturity and shed obovate bract–scale complexes that have a distinctive ribbed surface and an abaxial surface covered with abundant trichomes. The ovuliferous scale has ca. 30–40 resin canals, but only scarce xylem near the attachment to the cone axis. Resin vesicles are present in the seed integument. Phylogenetic analysis places Lepidocasus as sister to extant Cedrus within the abietoid grade. The exquisite preservation of the trichomes in L. mellonae raises questions about their potential ecological function in the cones of fossil and living Pinaceae. Lepidocasus mellonae also shows that a shedding dispersal syndrome, a feature that has often been overlooked, evolved early in the history of Pinaceae during the Early Cretaceous.

Dispersal ecology of flowering plants in a Late Cretaceous forest: new insights into angiosperm seed size evolution.

Jaemin, Lee, Dept. of Integrative Biology & Museum of Paleontology, University of California, Berkeley; Dori L., Contreras, Perot Museum of Nature and Science, Dallas; Garland, Upchurch, Texas State University at San Marcos; Cindy, Looy, Dept. of Integrative Biology, Museum of Paleontology & University and Jepson Herbaria, University of California, Berkeley

jaeminlee0622@berkeley.edu

Seed mass is an important ecological trait and is a predictor for several aspects of plants’ reproductive strategies including the number of seeds produced per allocated amount of energy for reproduction, dispersal mechanism, and seedling survival. Results from earlier studies suggest that Cretaceous angiosperms had mostly unassisted dispersal and relatively small seeds. During the early Cenozoic, both the average and range of seed sizes rapidly increased, and their dispersal syndromes became more diverse. Several hypotheses, (e.g., the coevolution, recruitment, and life-form hypotheses), attributed the observed pattern to either radiation of frugivorous vertebrates, or changes in plant community structure following the K-Pg extinction. Here, we present a new seed assemblage from the Late Campanian Jose Creek Member, McRae Formation from south-central New Mexico. The specimens come from a 1.2km-long bed of recrystallized volcanic ash that preserved a rich compression/impression flora representing a diverse megathermal forest – with angiosperms being the most dominant group across the landscape. The diaspore (plant dispersal unit) volume from this forest shows a significant departure from the hitherto described Cretaceous seed size pattern – both in the average and range. This pushes the establishment of larger diaspores in angiosperms back to the Late Cretaceous, approximately 20 million years earlier than previously suggested. This also weakens support for the ‘coevolution hypothesis’ which postulates the radiation of frugivores as the mechanism that sparks the increase in seed size. The Jose Creek diaspore flora suggests that large diaspores likely representing animal dispersal predate the radiation of major frugivorous vertebrate linages (ca. 55 Mya) by at least 20-million-years.

Fruit of Esgueiria from the Late Cretaceous of western Northern America.

Keana K. Tang, Department of Ecology and Evolutionary Biology and the Biodiversity Institute, University of Kansas, Lawrence, KS; Selena Y. Smith, Earth and Environmental Sciences and Museum of Paleontology, University of Michigan, Ann Arbor, MI, USA; Brian A. Atkinson, Department of Ecology and Evolutionary Biology and the Biodiversity Institute, University of Kansas, Lawrence, KS

keanatang@ku.edu

The Cretaceous record of North America successfully captures the initial diversification of angiosperms when modern lineages began to appear in rapid succession. Extinct lineages, however, have not been given as much attention and the Cretaceous flora from the western coast of North America are considerably undersampled which can hinder our understanding of early angiosperm evolution and diversity. Here, we report a structurally preserved fin-winged fruit from Campanian (Late Cretaceous) deposits on Sucia Island, Washington state, USA. The specimen was studied using light microscopy and micro-CT scanning. Persistent floral structures preserved on the fruit allowed us to use the phyloscan method to assess the fossil’s most parsimonious positions within the angiosperm phylogeny. The fin-winged fruit has a unilocular ovary, five fin wings that longitudinally extend along the fruit body, five persistent calyx lobes that alternate with the wings, raised mounds of tissue (possibly nectaries) outside of the androecium, at least four stamen filaments within two whorls, and three styles that are fused for half of their length.. The general morphology of the fin-winged fruit resembles fruits of the family Combretaceae, but extant members of the family only have a single style. However, the fin-winged fruit is assignable to the extinct genus Esgueiria, a potential stem lineage of Combretaceae from the Cretaceous of Japan and Europe. Morphological differences such as the degree of fusion at the base of the styles suggests the fin-winged fruit represents a new species of Esgueiria. Phyloscan analyses of Esgueiria recovered three most parsimonious positions within the core eudicots and as a stem lineage of core eudicots, but fail to recover the genus within Combretaceae. These ancient plants likely represent an extinct family of angiosperms. The recovery of extinct lineages will undoubtedly help us better understand the early evolution of angiosperms.

Bleximothyrium ostiolatum, a new fossil fly-speck fungus from the Lower Cretaceous Potomac Group and its interpretation through phylogenetic comparison with extant species.

Ludovic, Le Renard, University of British Columbia; Ruth, Stockey, Oregon State University; Garland, Upchurch, The University of Colorado; Mary, Berbee, University of British Columbia

ludovic.lerenard@botany.ubc.ca

Through analyzing well-preserved fossil scutella, shield-like covers of fungal sporocarps, we describe a new taxon of early Dothideomycetes. Sediments from the Potomac Group, Lower Zone 1, Lower Cretaceous (Aptian) of Virginia, yielded a single gymnospermous leaf cuticle colonized by 21 sporocarps of one fungal morphotype. We inferred a tree from nuclear ribosomal DNA of extant fungal species, and coded morphological characters to evaluate alternative, equally parsimonious placements of the fossils in a molecular constraint tree. Bleximothyrium ostiolatum has an ostiolate scutellum of radiate, dichotomizing hyphae connected to extensive subcuticular “mycélium en palmettes”. Our analysis revealed equally parsimonious placements of the fossil across distantly related lineages of Dothideomycetes. Scutella of B. ostiolatum have tangled hyphae at the scutellum margin, a character that is not found in similar extant and fossil taxa. It is the oldest fossil fly-speck fungus found on plant cuticles that has the radiate, ostiolate scutellum known only from Dothideomycetes. The combination of characters found in B. ostiolatum is unknown in other extant and fossil species, and suggests it may represent a group of fly-speck fungi that is now extinct. This and previously described fungi from the Potomac Group add evidence for the appearance of distinct lineages of Dothideomycete fungi during the Late Mesozoic, helping to document morphological changes that occurred early in their evolution.

In situ spores of leptosporangiate ferns from the Triassic in Europe.

Hendrik Nowak, Museum of Nature South Tyrol, Bozen/Bolzano, Italy; Evelyn Kustatscher, Museum of Nature South Tyrol, Bozen/Bolzano, Italy; Department für Geo- und Umweltwissenschaften, Paläontologie und Geobiologie, Ludwig-Maximilians-Universität, München, Germany; Bayerische Staatssammlung für Paläontologie und Geobiologie, München, Germany

hendrik.nowak@naturmuseum.it

Spores and pollen are produced in large numbers by plants and distributed by wind, water or animals up to tens of thousands of kilometers away from the source area. Thanks to this and their high preservation potential, they are particularly useful for the reconstruction of environments and biotic responses to the climate of the past. However, in order to reconstruct the botanical affinity of these dispersed sporomorphs, we have to identify the original plant, and in particular the corresponding reproductive organs. Spores or pollen from a single plant species or even an individual plant or sporangium may vary in shape to a point that equivalent forms that were found dispersed in the sediment have been described as different species or even genera. In addition, not all these organs were ripe at the moment of the burial, and therefore they do not always contain completely developed microspores. In order to better understand these variations, we studied the intraspecific and interspecific morphological variability of in situ spores of leptosporangiate ferns (belonging to the Osmundales, Gleicheniales, and Schizaeales) from the Triassic of Europe. The material mainly comes from the Anisian Kühwisenkopf/Monte Prà della Vacca flora of Italy and the Carnian Lunz flora of Austria. Our analysis is aimed at distinguishing characters that can serve to identify specific taxa from those that fall into the normal range of variability, differentiating developmental stages, and determining the frequency of malformed grains, which may provide evidence for environmental disturbances affecting plant reproduction.

Developmental origins of pollen malformations.

Jeffrey P. Benca1*, Ivo A.P. Duijnstee2, Cindy V. Looy2,3

jbenca@uw.edu

Heightened frequencies of saccate pollen malformations have been interpreted as a proxy for environmental stress in the fossil record. However, the developmental origins of these deviations in the microsporogenesis process are not well understood. To determine which types of disruptions to microsporogenesis could have produced teratologies in saccate pollen of the past, we reviewed cytology literature on developmental deviations in modern saccate pollen producing conifers. Historical studies indicate that phenotypic malformations in modern saccate pollen not only associate with a range of irregularities during microsporogenesis, but also production of unreduced (>2n) pollen grains. We describe and diagram a hypothesized framework for the developmental origins of malformation traits, corresponding with irregularities during (1) meiosis, (2) the tetrad stage, and (3) the free microspore stage. Using this framework, it may be possible to interpret—based on morphological traits—which stages of pollen ontogeny were most likely disrupted by environmental stresses inferred by abnormal palynological assemblages.

Using morphological leaf functional traits to characterize ancient plant community ecology

Alexander Lowe, Caroline Strömberg, Department of Biology, University of Washington

loweaj01@uw.edu

In neo-ecology, functional traits, as opposed to species identities alone, are increasingly used to describe plant community ecology, as they relate more directly to ecosystem function and community responses to environmental change, are more applicable across vegetation types that share few taxa, and their distribution in a plant community can provide clues to community assembly processes. Although many of the traits that neo-ecologists analyze cannot be assessed from fossil remains (e.g., C/N ratios), there are several applicable morphological leaf functional traits. These measures of leaf shape, size, and toothedness have been used to develop methods to reconstruct ancient climates (i.e., ‘a means to an end’), but have been less utilized in describing the ecology of the plant community itself (e.g., functional diversity, community assembly, prevalent ecological strategies, vegetation structure, community resiliency, ecosystem function). One important exception is estimates of leaf mass per area from its relationship with ‘petiole stoutness’ (=petiole width^2 / leaf area), although it is still unclear to what extent community-level distributions of petiole stoutness vary within and between different environments. To address these issues, we are expanding on the community-level modern leaf dataset of Peppe et al. (2011) to include Chinese sites from Su et al. (2010, 2013). We use univariate and multivariate methods to test if, in different Köppen climate types, central moments of morphological leaf functional traits (including petiole stoutness), and functional diversity indices that include these traits, vary in a manner consistent with neo-ecological theory and observations. Preliminary results show that community-level mean varies significantly between climate types, driven mainly be leaf area and tooth count (PCA), but variance does not (R2 = 0.55, 0.13, respectively; PERMANOVA). Estimates of functional richness were higher in favorable climate types (e.g., tropical monsoon) and lower in harsher climate types (e.g., cold temperate, arid), consistent with ecological theory. These preliminary results show some promise for applying similiar methods to reconstruct aspects of ancient plant community ecology, though also highlight that more work is needed (e.g., how to categorize sites by enviornment).

The Analysis of Palm Phytolith Morphology as a Paleoecological and Paleobotanical Tool

Andrew, Markham, Department of Biology at University of Washington; Samuel, T. Lavin, Department of Biology at University of Washington; William, Brightly, Department of Biology at University of Washington, Burke Museum of Natural History and Culture; Camilla, Crifò, Department of Biology at University of Washington, Burke Museum of Natural History and Culture, Institut des Sciences de l’Evolution de Montpellier (ISEM), EPHE, PSL Research University, Université de Montpellier; Timothy, J. Gallaher, Department of Biology at University of Washington, Burke Museum of Natural History and Culture; Alex, Lowe, Department of Biology at University of Washington, Burke Museum of Natural History and Culture; Alice, Novello, Department of Biology at University of Washington, Burke Museum of Natural History and Culture, Aix-Marseille Universite; Elena, Stiles, Department of Biology at University of Washington, Burke Museum of Natural History and Culture; Paige, K. Wilson, Burke Museum of Natural History and Culture, Department of Earth and Space Sciences at University of Washington; Caroline, A.E. Strömberg, Department of Biology at University of Washington, Burke Museum of Natural History and Culture

markhama@uw.edu

Phytoliths are microscopic silica structures produced in plant tissue, and palms (family Arecaceae) are prolific producers of them. The stability of these structures contributes to the abundance of palms in the fossil record, as they fossilize in sediments where leaves cannot, providing a wider range of evidence of palm paleogeographic distribution. Palms generally grow in warmer and wetter environments, but certain species can live in more extreme climates (i.e., cold, dry). However, because 90% of palms are currently distributed around the equator and in tropical rainforests, they are often used as an indicator of warmer, and wetter, environments in the fossil record. Currently, understanding of phytolith morphological variation within Arecaceae is limited, and it is unclear whether phytoliths can be used to identify different palm groups in the fossil record. We hope to address this knowledge gap by studying palm phytolith shape and size variation using a morphometric approach. The phytoliths of over 100 species of modern Arecaceae and X species of appropriate outgroup species (~30 images/species) were imaged with a confocal microscope, and a semi-automated script in ImageJ quantified the shape descriptors of each phytolith as we determine the morphology. Next, we used multivariate analysis of the morphometric data to distinguish the phytoliths of modern subfamilies based on distinct morphological traits, forming a quantitative baseline to classify phytoliths. We combined our shape/size data with climate and temperature data to test for links between phytolith shape and the growth environment of modern palm species. We then applied the same analysis to fossil phytoliths of unknown origins to determine which palm clade they most resemble, and predict an approximate paleohabitat. Our method has the potential to improve our ability to use palm phytoliths to enrich paleoecological reconstructions and document the evolution and past biogeography of the palm family.

Exploring variable resolutions of leaf morphotype approaches on paleoclimate reconstruction: A case study using the Eocene Florissant paleoflora, central Colorado

Anna Golub, Department of Geology and Environmental Geosciences, Lafayette College, Easton, PA 18042, USA; David Sunderlin, Department of Geology and Environmental Geosciences, Lafayette College, Easton, PA 18042, USA; Sarah E. Allen, Department of Biology, Penn State Altoona, 3000 Ivyside Park, Altoona, PA 16601, USA; Herbert W. Meyer, National Park Service, Florissant Fossil Beds National Monument, P.O. Box 185, Florissant, CO 80816, USA

agolub15@gmail.com

Morphotyping a fossil dicot leaf flora is an important early step in leaf physiognomic approaches to estimating terrestrial paleoclimates. While paleoecologists are guided by accepted leaf scoring protocol, variance still exists between practitioners, some tending to split morphotypes more finely within an assemblage, others tending to lump specimens with greater morphological disparity within a single morphotype.We tested the sensitivity of paleoclimate estimates to possible variations in differentiating leaf morphotype resolution by morphotyping one paleofloral collection three times, each using a different degree of resolution, and comparing results from leaf physiognomic methods. We performed this analysis on a recently collected Eocene (34 Ma) fossil leaf assemblage from Florissant Fossil Beds National Monument Collection Site 9 (CS-9, Florissant, Colorado), an exposure yielding one of the most diverse sets of dicot morphotypes yet analyzed from a single site within this well-studied formation. We grouped this collection using what we refer to as a ‘Splitter’ scheme (n=129 morphotypes) which had the greatest degree of anatomical discrimination, an ‘Intermediate’ scheme (n=96), and a ‘Lumper’ scheme (n=53) which combined similar leaf morphologies with the idea that they could represent intraspecies variability. On each resolution we performed Leaf Margin Analysis, Leaf Area Analysis, and Climate Leaf Analysis Multivariate Program to obtain paleotemperature and paleoprecipitation estimates. The three approaches provided very similar paleoclimate estimates by all above methods of analysis, a result suggesting that, to some degree, morphotype resolution specificity has little effect on paleoclimate results using these techniques. Overall results produced a mean annual temperature estimate between 10.8 and 12.5ºC, and precipitation between 62 and 131 centimeters at the time of deposition, with similar error across all resolutions. The CS-9 paleoflora indicates a temperate late Eocene climate at Florissant regardless of resolution, generally corroborating earlier leaf physiognomic estimates but indicating higher precipitation than most prior studies.

Paleobotany and Stratigraphy of the Lower-Aptian to Middle-Albian in the Central Sub-Andean Zone of Ecuador

Daniela, Quiroz, Yachay Tech University; Fabiany, Herrera, Chicago Botanic Garden; Jorge, Toro, Yachay Tech University; Mónica, Carvalho, Smithsonian Tropical Research Institute; Camila, Martínez,Smithsonian Tropical Research Institute

dany.e88@hotmail.com

Cretaceous paleofloras from South American low latitudes are poorly understood due to scarce research exploration that has been conducted in these areas. Today, this region holds high plant species diversity; therefore, investigating Cretaceous macrofloras can shed light on the initial diversification of flowering plants and conifers as well as to the paleoenvironment in which those Early Cretaceous forests grew up in Gondwana. Recently, we explored the paleobotanical record and stratigraphy of the Lower Hollin Formation, a clastic stratigraphic unit dated as Lower (?) Aptian to Middle Albian, outcropping in the Central Eastern Sub-Andean Zone of Ecuador (SAZ). Aiming to reconstruct the paleoenvironment of the Lower Hollin Formation, we collected and studied plant macrofossils, and we described three stratigraphic sections in detail. The stratigraphic columns show massive, horizontal-laminated, through and cross-bedded fine- medium- to coarse-grained quartz-rich sandstones forming fluvial channels, fluvial bars, fluvial plains facies, few delta plains and delta lobe facies, interbedded with few horizontally-laminated siltstones and shales associated to lacustrine facies. The results determine a fluvio – delta - lacustrine clastic depositional environment for the Lower Hollin Formation dominated by braided stream rivers, little deltas and lacustrine flooding events. From the macrofossils collected, we observed leaf samples with parallel-venation, fronds, and also well-preserved cuticles. Regarding the probable taxonomic affinities of the fossils, we indicate the presence of conifers families such as Cupressaceae, and Podocarpaceae, fern fronds like Selaginella, and a few angiosperms leaf morphotypes. Furthermore, there is abundant evidence of amber associated with the plant macrofossils in the stratigraphic sequences. Moreover, we can infer humid conditions for the deposition of sandy to shaly sediments of Lower Hollin Fm. Our results contribute to our understanding of the evolution of the tropical belt, which is today the most biodiverse region in the world.

Paleobotany of the early Permian Hermit Formation, Grand Canyon National Park

Erikka, Olson, Grand Canyon National Park; Anne, Miller, Grand Canyon National Park; Mark, Nebel, Grand Canyon National Park

erikka_olson@partner.nps.gov

Grand Canyon National Park in northern Arizona preserves a rich geologic and paleontological history, with strata containing fossils from almost 2 billion years of Earth’s history. Of high paleobotanical significance is the early Permian Hermit Formation (~280 Ma), which represents a coastal plain with river channels cut into the underlying Carboniferous- early Permian Supai Group. Its interbedded mudstones, siltstones, and sandstones contain a diverse assemblage of plant fossils, including conifers, pteridosperms, sphenophytes, and algae. Many of these fossils are preserved in situ and in upright growth position. This paleoflora is significant not only in its geographic context in western equatorial Pangaea, but also in its temporal context in the early Permian. The Hermit Formation and underlying Supai Group provide an interesting opportunity to study a plant community’s response to global climate variations, as Earth transitioned from a glaciated to ice-free interval during the Carboniferous to early Permian. While other Permian floras from the American Southwest have been the subject of extensive research, few studies have been done in the Grand Canyon. Most of our knowledge of the Hermit Formation stems from the work of paleobotanist David White in the 1920s. One hundred years after White’s seminal research, recent field work has yielded exciting fossil discoveries which underline the need for further study of this formation and the Paleozoic paleobotany of the Grand Canyon. Much work remains to describe the paleoecology of the Hermit Formation itself to better understand its broader significance in global plant evolution and community responses.

Applying 3D rendering and glass sculpture techniques to representing microbotany in public exhibitions

Julie D. Carrasco1, Timothy Gallaher1,2,3, Caroline A. E. Strömberg1,3 1Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98195, USA 2Bishop Museum, Honolulu, HI 96817, USA 3Department of Biology, University of Washington, Seattle WA 98195, USA

jules.carrasco@gmail.com

Phytoliths, plant opal, are microscopic silica bodies naturally deposited and preserved in the shapes of plant cells, their surrounding area, and tissues. These microfossils are useful for examining the evolution of plant groups and of ecosystems in deep time, due to their resistance to decay in oxidized sediments. Despite their importance, phytoliths and their research can be abstracted by their microscopic stature to non-scientists and the general public.To bridge this gap in awareness, we are designing a sculptural exhibit of glass phytoliths. The abstract forms of phytoliths are well-suited to artistic expression. As silica (oxidized silicon), is abundantly present in both artistic casting glass and phytoliths, glass provides a faithful medium for depicting these forms. We are using 3D scanning and printing techniques, coupled with warm glass casting processes to artistically depict enlarged phytoliths in an archival form. Our resulting exhibition spotlighting phytoliths has the potential to reach broad audiences that would otherwise have limited exposure to this field. Additionally, our outreach may help increase public awareness for the interconnectedness between scientific disciplines such as microbotany with paleoecology and global change biology.

Revisiting R.H. Tschudy's Fern Spike Concept 40 Years Later

Keith Berry, Hoehne Schools

keith.berry@hoehnesd.org

Forty years ago, R.H. Tschudy developed the concept of the K/Pg boundary fern spike, a period in which ferns rapidly recolonized western North America by wind-blown spores in the immediate wake of the Chicxulub asteroid impact. Many researchers have attributed the dispersed fern spores in the fern spike interval to tropical tree ferns (Cyatheales), a concept that appears to be supported by recent genomic evidence supporting whole genome duplication (WGD) in Cyatheales across the K/Pg boundary. WGD in association with the K/Pg boundary supports the precept that Baker’s Law explains the high colonization potential of these wind-blown spores, as Tschudy originally conceived. On the basis of megafloral evidence, however, there are a number of ground ferns that proliferated during the K/Pg fern spike in western North America that are also known to have produced Cyathidites spores, including basal polypod ferns and Anemia-like ferns. In the vicinity of the region where Tschudy developed the fern spike concept, the latter group appears to have dominated pteridophyte assemblages during the earliest Paleocene. Prior to the K/Pg mass extinction, however, Anemia-dominated assemblages are not known to be early successional in origin and have instead been postulated to be late relics of a period before angiosperm dominance (e.g., Big Cedar Ridge). Rather than reflecting a clear-cut, textbook example of ecological replacement of ferns by competitively superior angiosperms, the association of the fern spike with Anemia-like ferns raises interesting questions about the pattern of plant succession across the K/Pg boundary, a few of which are addressed here.

Fossil Paullinieae from the early Miocene of Panama and implications for the diversification of lianas in Sapindaceae

Nathan A. Jud, William Jewell College; Sarah E. Allen, Penn State Altoona; Chris W. Nelson, Gainesville, FL; Carolina L. Bastos, Universidade de São Paulo; Joyce G. Chery, Cornell University

judn@william.jewell.edu

Vines and lianas in the soapberry family (Sapindaceae) comprise the monophyletic tribe Paullinieae. The tribe includes 6 extant genera and approximately 475 species, or about one quarter of the family. Many of these plants have complex stem anatomy that allows them to twist and bend without breaking. To better constrain the diversification history of this important group, we reviewed the macrofossil record of Paullinieae and described a new species based on permineralized roots from the Miocene Cucaracha Formation in Panama. The fossil roots from Panama consist of a central woody cylinder surrounded by peripheral tissues (bark) that also include distinctive peripheral vascular strands known as successive cambia, typical of some Paullinieae. The combination of peripheral vascular strands, vessel dimorphism, wide vessels solitary or in short tangential multiples, narrow vessels in long radial multiples, alternate intervessel pits with slit-like coalescent apertures, heterocellular rays, prismatic crystals in axial parenchyma and dark content (possibly phenolic compounds) in primary vascular parenchyma and ray parenchyma support the inclusion the new fossil taxon in Paullinieae. To test the hypothesis that the roots belong to crown-group Paullinieae, we performed a combined-evidence phylogenetic analysis in MrBayes v.3.2.7. The matrix consists of 216 species and 1517 characters divided into three partitions: wood anatomy (1-28), ITS (29-882), and trnL intron (883-1517). The phylogenetic analysis consistently resolved the fossil taxon within crown-group Paullinieae. Apart from the fossil roots, all previous reports of Paullinieae macrofossils are based on fossil leaves but none preserve leaf architectural characters diagnostic of the tribe. Thus, the fossil roots from the early Miocene of Panama are the oldest reliable evidence of Paullinieae and they provide strong evidence of the evolution of lianas in Sapindaceae by 18.5-19 million years ago.

North American grasslands expanded as winters grew drier

Tyler Kukla, Geological Sciences Department, Stanford University; Jeremy K Caves Rugenstein, Department of Geosciences, Colorado State University; Daniel E Ibarra, Department of Earth and Planetary Sciences, University of California, Berkeley; Matthew J Winnick, Department of Geosciences, University of Massachusetts Amherst; Caroline AE Strömberg, Department of Biology, University of Washington; C Page Chamberlain, Geological Sciences Department, Stanford University

tykukla@stanford.edu

Open habitat grasslands replaced woodlands across western and central North America between ~25 and 18 million years ago. The cause of this transition is unknown, but global warming, global cooling, increasing precipitation, and drying have all been implicated. One of the most commonly cited hypotheses is that grassland expansion was driven by the onset of seasonal aridity---usually, drier summers. We test this hypothesis with a compilation of new (n=117) and published (n=2102) oxygen isotope measurements (δ18O) from authigenic clays and soil carbonates spanning the Eocene to Pliocene (~50-5 Ma). Comparing clay and carbonate δ18O can inform the seasonality of precipitation because carbonates can form seasonally, usually in drier conditions when soil CO2 is declining, while clays form more slowly, capturing long-term mean conditions. Changes in precipitation seasonality can therefore have different effects on each mineral. These climate proxy data are compared to a record of Eocene-Pliocene vegetation change based on published phytolith assemblage data (n=256) from the same region. We report a decrease in the difference between clay and carbonate δ18O coincident with grassland expansion. This result cannot be explained by changes in global temperature or a shift to drier summers, but is instead consistent with a decrease in winter precipitation. Winter drying was likely driven by tectonics, which sets gradients in precipitation seasonality and vegetation today. We suggest woodlands in west-central North America were adapted to a wet-winter precipitation regime for most of the Cenozoic and they struggled to meet water demands when winters became drier, presenting an opportunity for grassland expansion.

The role of grasslands in the evolution of seed dispersal strategy in the Poaceae

William H. Brightly, University of Washington Department of Biology; Matheus E. Bianconi, Department of Animal and Plant Sciences University of Sheffield; Caroline A. E. Strömberg, University of Washington Department of Biology

whbright@uw.edu

Habitats dominated by grasses are globally important, accounting for approximately 40% of terrestrial ecosystems. The assembly and expansion of these habitats began during the late Oligocene - early Miocene, and was one of the most consequential ecological events of the last 66 million years. We explore the effect that this transition had on the evolution of grass seed dispersal strategy, a biologically important process with wide ranging consequences for plants and their communities. For grasses, the expansion of grassland habitats likely altered interactions with potential dispersers (e.g., the rise of grazing faunas) and the geographic distribution of suitable habitats, both of which influence dispersal outcomes. Using a phylogenetic comparative approach, we tested whether or not occupation of grassland habitats was associated with changes in dispersal characters in grasses. We collected diaspores (unit of seed dispersal) of ~200 species of grasses. For each, morphological characters (mass, callus type, shape, surface roughness, falling velocity) were used to estimate dispersal potential for anemochorous (wind), epizoochorous (external animal), and endozoochorous (internal animal) dispersal. For each strategy, we fit several evolutionary models, which varied in whether grassland and non-grassland taxa occupied distinct evolutionary regimes. Preliminary results did not reveal systematic differences in relation to epizoochory or endozoochory, though grasslands appeared to favor anemochory. Evolution of increased wind dispersal potential in grasslands may reflect greater viability of this strategy in these open environments. Transitions away from the family’s ancestral understory habitat may have also relaxed selection for larger seed sizes, which are typically associated with full shade, making anemochory more practicable. Fossil diaspores, collected from late Oligocene and Miocene sites in Kansas and Nebraska, are currently being incorporated into our dataset. These taxa occupied some of the earliest grassland communities in North America. Their incorporation into our comparative framework will provide additional insight into this question.

Isolation and Analysis of the Palynomorphs from Khadro Formation Exposed at Ranikot Fort Area Sindh, Pakistan.

Dileep Kumar Kataria1*, Noorulain Soomro2, Rafique Ahmed Lashari3, Shabab Ali Khan2

noorulain@usindh.edu.pk

The main purpose of this research was to evaluate palynological analyses of the Khadro Formation outcrop sections. The findings identify 17 Palynomorphs from the Khadro Formation at Ranikot Fort Sindh, Pakistan.. Majority of samples contained Angiospermic and algal microfossils. Algal remains disclose the prevalence of sub-tropical to tropical, in which marine environmental species were Chaetomorphaakineta, Zygnematerrestre and Synechococcus aeruginosusand also including fresh water species such as, Pinnularia denticulate, Oscillatoria vizagapatensis and Genecularia sp.Arecaceae & Nymphaeaceae also indicated the fresh water vegetation. The remains of fungal spores of Dicellaesporites minutus indicate’s the deposition time of Khadro Formation and the environmental conditions that was humid, hot, and with heavy rain fall. Presence of the Pteriodophytic spores (Laevigatosporites sp.) indicated that environment was deltaic, swampy and being estuarine. From Palynomorphs of different groups based on distribution pattern, confirms that during deposition time of Khadro Formation at early environmental condition was hot.

Phylogenetically-informed computer vision methods for fossil pollen classification: some ecological and evolutionary implications.

Marc-Elie, Adaime, Department of Plant Biology, University of Illinois Urbana-Champaign; Shu, Kong, Robotics Institute, Carnegie Mellon University; Surangi W., Punyasena, Department of Plant Biology, University of Illinois Urbana-Champaign

madaime2@illinois.edu

The combination of superresolution imaging and automated classification was recently proposed as a powerful tool for fossil pollen identification and was shown to greatly improve our ability to use palynological data in ecological and evolutionary research. So far, however, this approach has focused on image-level identifications that classify specimens based on overall visual similarity, which poses a challenge when dealing with extinct taxa associated with unique morphological features. Additionally, deep-time specimens can be taphonomically altered and distorted due to poor preservation, creating a bias in identification. We designed a robust-to-fragmentation (patch-based) convolutional neural network (CNN) model to classify fossil pollen of two different groups: the genus Podocarpus and the Malvaceae subfamily Bombacoideae. Furthermore, we developed a novel dissimilarity-based learning network that relies on an existing molecular phylogeny to identify the species using a cost matrix that reflects the clade’s evolutionary history. Our results indicate that the patch-based system yields markedly better classification performance compared to conventional, whole image-based methods, meaning it can be confidently used with distorted fossil specimens. The phylogenetically-informed network shows even greater performance improvement, indicating strong phylogenetic signal and suggesting that evolutionary trees can be potentially used to guide computer vision tasks involving fossil data. These models will lead to reproducible results that rely on a quantitative-based approach rather than somewhat subjective interpretations and may allow us to unveil cryptic evolutionary responses such as extinction and speciation events that would otherwise be masked by the limited taxonomic resolution of the fossil pollen record.

Terrestrial pollen carbon isotope record across the Paleocene-Eocene Thermal Maximum.

Vera A. Korasidis - Department of Paleobiology, Smithsonian Institution, Washington, DC 20560, USA. Scott L. Wing - Department of Paleobiology, Smithsonian Institution, Washington, DC 20560, USA. David M. Nelson - Appalachian Laboratory, University of Maryland Center for Environmental Science, Frostburg, MD 21532, USA. Allison A. Baczynski - Department of Geosciences, The Pennsylvania State University, University Park, PA, USA. Guy J. Harrington - Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.

korasidisv@si.edu

Paleobotanical research on Paleocene-Eocene Thermal Maximum (PETM) megafloras in the Bighorn Basin, USA, has emphasized that their composition is radically different from those immediately before and after the PETM. Palynofloral change in the same studied sections was, in contrast, remarkably subtle, with only rare occurrences of pollen types generally more common in the southerly Gulf Coastal plain recorded during the PETM interval. To investigate this discrepancy, we employed traditional palynological analysis and novel species-specific pollen stable carbon isotope analysis on numerous Bighorn Basin successions. We found that pollen taxa of temperate affinity (i.e., Cupressaceae, Juglandaceae) are poorly preserved during the PETM, whereas pollen taxa of tropical affinity (i.e., Arecaceae) are well preserved. We also found that the δ13C of PETM pollen taxa with a temperate affinity are similar to pre-PETM grains of the same taxon. However, the carbon isotopic composition of pollen grains of tropical affinity from the PETM is significantly lighter (i.e., by 4 per mil) than the same taxon before the PETM. We propose that the poorly preserved temperate taxa, that do not show a shift in carbon isotopic composition during the PETM are likely reworked. The increased abundance of Cretaceous spores, pollen and dinoflagellates in samples derived from the PETM body is consistent with this interpretation. We conclude that the enhanced reworking of palynotaxa, due to the sudden onset of more seasonal precipitation, could explain the reduced turnover in palynofloras previously reported for the Bighorn Basin PETM successions. These findings also make it probable that temperate plant lineages were extirpated throughout the Bighorn Basin during the body of the PETM. Caution is therefore required in high-resolution palynological studies of intervals with major climate change documented.

Two redwood genera (Sequoia and Metasequoia) from Miocene Hannuoba Formation, Inner Mongolia, Northern China: Preservation, cuticular characters, and CO2 reconstruction.

Jia-Qi, Liang; Qin, Leng; Liang, Xiao; Hong, Yang

jliang2@bryant.edu

The Miocene Hannuoba Formation at the southeastern edge of the Mongolian Plateau in East Asia is composed of Hannuoba Basalts (24-18 Ma) and embedded fluvial and lacustrine deposits that host rich faunal and floral fossils. Leafy branchlets of two redwood genera Sequoia and Metasequoia (subfamily Sequoioideae, family Cupressaceae) are commonly found co-occurring in the Zhuozi County, Ulanqab City, Inner Mongolia Autonomous Region, northern China. A modified cleared leaf preparation method revealed new micro-morphological features of these two genera and allowed accurate measurements of various stomatal parameters for both traditional paleobotanical and paleoenvironmental studies. In contrary to prevailing even type cuticles found in Metasequoia fossils through geological times, the Inner Mongolian Miocene Metasequoia exhibits exclusively uneven type cuticular characters that are common in extant dawn redwood populations. Sequoia leaves from this fossil site are amphistomatous. Pyrolysis–GC–MS analysis showed that these fossils preserve exclusively stable biomolecule lignin with only one labile polysaccharide pyrolysate (2-Methyl-2-cyclopentene-1-one) detected in Sequoia fossil leaves. They also show considerable amounts of cuticle decay as indicated by pairs of long-chain aliphatic n-alk-1-enes/n-alkanes with long retention times. Supported by anatomical observations, the preservation of common compressions of Inner Mongolia fossils demonstrated a good potential for wider applications of the cleared leaf preparation method. Stomatal data obtained from large fragments recovered through the cleared leaf method afforded us the assessment of natural variations in the fossil population and allowed us to compare multiple proxies of reconstructing ancient atmospheric CO2 concentrations such as the stomatal index method and the Franks leaf gas exchange model.

The Miocene Flora of Orhaneli Basin (Bursa, Turkey): preliminary results.

Çılga Sanem, Koç, Department of Biology, Ege University, İzmir, Turkey; Friederike, Wagner-Cremer, Department of Physical Geography, Utrecht University, Utrecht, The Netherlands; Timme Henrik, Donders, Department of Physical Geography, Utrecht University, Utrecht, The Netherlands; Hasan, Yıldırım, Department of Biology, Ege University, İzmir, Turkey

cilgasanemkoc@gmail.com

Neogene sedimentary deposits of Western Anatolia accumulated in lacustrine depositional settings and most of these sediments contain coal. This study is based on detailed palaeobotanical investigations of Miocene coal deposits exposed in the Aegean region in Bursa, Orhaneli. Miocene sediments in the Orhaneli Basin are rich in macrofossils and microfossils. Plant macro fossils with special emphasis on leaves were collected from the Burmu formation that contains the main lignite coal seam at the bottom and marls in the upper parts. The aim of this study is to reconstruct landscapes and vegetation in the area based on the ecological requirements of the flora elements. Since the summer of 2018, we had plenty of field works and followed the new opening sides in the basin. About 2000 macrofossils (leaves, seeds, fruits, cones) from Orhaneli basin are recorded in the paleobotany collection of Ege University Botanical Garden and Herbarium Researches & Aplication Center. Based on the identified samples, we show that the dominant Angiospermae taxa of the Orhaneli basin are Lauraceae and Fagaceae while the dominant Gymnospermae taxa are Cupressaceae and Pinaceae. According to the vegetation characteristics of plant groups represented by the Orhaneli leaf fossils, Miocene marsh vegetation included Glyptostrobus europaeus and Phragmites sp.. The vegetation near rivers comprised Salix sp., Acer sp. and Myrica lignitum. In addition, Zelkova zelkovifolia is a common element in the plant-bearing layers. Fagus gussonii, Quercus spp., Mahonia sp. and others were part of well-drained mixed forests. Quercus mediterraneae was a characteristic elements in the flora. Besides evergreen oaks, Daphnogene polymorpha was dominant in the broad-leaved evergreen forests. According to the macro floral elements, we estimate that during the middle Miocene in the Orhaneli Basin, river-fed marshes and riparian forests thrived while broad-leaved evergreen forest was present in the surroundings of the basin.

Leaves of Araceae from the late Paleocene of Alberta, Canada: Orontiophyllum grandifolium comb. nov.

Georgia L. Hoffman, self-employed; Ruth A. Stockey, Oregon State University; Gar W. Rothwell, Oregon State University

ghoffman@ualberta.net

Nearly 200 araceous leaves and leaf fragments have been identified among late Paleocene (Middle Tiffanian, Ti3, ~60 Ma) fossils from the Blindman River locality near Blackfalds, Alberta, Canada. Their leaf architecture closely resembles that of extant Lysichiton Schott (Araceae, Orontioideae). The lamina is simple, elliptic to ovate or oblong in shape, with an entire margin, an acute to slightly rounded apex, and a cuneate to obtuse or cordate base. The broad petiole, which continues into the basal portion of the lamina as the midrib, includes numerous veins that diverge into the lamina as parallelodromous primary veins. The primary veins are of two weakly differentiated width classes designated A (thicker) and B (thinner), usually in the pattern ABAB. Primary veins do not dichotomize; they converge with a submarginal vein in the upper portion of the lamina, or at the apex. Transverse veins that connect two or more primary veins are perpendicular or nearly perpendicular to the primary veins, straight to slightly curved, and of a single width class. Higher-order veins of a single width class form rectangular to polygonal areoles. Many laminae have holes or patches surrounded by necrotic tissue that resemble damage caused by slugs or fungal rot. These leaves are referred to the genus Orontiophyllum J.Kvaček & S.Y.Smith that was erected for dispersed fossil leaves with venation like that of extant Araceae, Subfamily Orontioideae. The basionym for the specific epithet comes from the holotype specimen, which was collected at the Blindman River locality in 1889 and originally described as Majanthemophyllum grandifolium Penh. The geologic setting and associated plant and animal fossils indicate that, like today's orontioid Araceae, the plant that bore these leaves lived in a permanently wet or moist area at the margin of a floodplain lake or marsh.

Fossil spadices: Bognerospadix and the Paleocene diversification of Araceae.

Ruth A. Stockey, Oregon State University; Georgia L. Hoffman, G. Hoffman Consulting Services, Calgary, AB; Gar W. Rothwell, Ohio University, Oregon State University

stockeyr@oregonstate.edu

Two compressed fossil spadices with partially permineralized seeds associated with araceous leaves have been identified from the Paleocene Blindman River locality near Blackfalds, Alberta, Canada. Spadices are cylindrical, more than 4 cm long, with numerous helically arranged, bisexual, perigoniate flowers, each with six free tepals. Tepals are in two whorls, free, triangular, and hooded. The gynoecium is flask-shaped, and the stylar region is long, conical, and exserted beyond the tepals. The ovary is trilocular with axile placentation and one ovule per locule. Seeds are slightly curved, hemianatropous, and verrucose with a seed coat of several layers of isodiametric sclereids. Spadices have been compared to those of extant and extinct Araceae and show closest morphological similarities to those of Lysichiton and Spathiphyllum. Although not found in attachment to the leaves, these probably represent parts of the same extinct plant species. Phylogenetic analyses using a morphological matrix of living and fossil Araceae were performed using TNT version 1.5 to help establish relationships of the fossil leaves and spadices within Araceae and to each other. Leaves and spadices each conform to an early-diverging lineage of Araceae, increasing the known diversity of Proto-Araceae (viz., subfamilies Gymnostachydoideae and Orontioideae). Together, they provide strong evidence for extinct Proto-Araceae with novel combinations of characters shortly after the Cretaceous-Paleogene floral transition.

Fruits and seeds of the mid-Paleocene Tongue River Member of the Fort Union Formation, southeastern Montana.

Indah, Huegele, University of Florida; Steven, Manchester, University of Florida

indah.huegele@ufl.edu

We present an assemblage of three-dimensionally preserved fossil fruits and seeds from the mid-Paleocene Newell's Nook locality in the northern Powder River basin of southeastern Montana. This locality lies in the Tongue River Member of the Fort Union Formation and has previously yielded 21 species of vertebrates, including fish, turtles, crocodiles, and mammals, which indicate an early Tiffanian (or latest Torrejonian) age. Fruit and seed material was collected alongside the vertebrate material but was not previously described. The collection of about 65 specimens, representing about a dozen morphotypes, was extracted by soaking samples of clay clast conglomerate in kerosene for a few days and then immersing in water prior to sieving. We have identified specimens of the genera Diploporus, Taxus (Taxaceae), Palaeoluna (Menispermaceae), Kingsboroughia (Sabiaceae), Jenkinsella (Cercidiphyllaceae), Vitis (Vitaceae), Polyptera (Juglandaceae), Diclidocarya (Lythraceae), Zanthoxylum (Rutaceae), as well as some belonging to Cucurbitaceae, Hamamelidaceae, and several of uncertain affinities. Several specimens represent a new genus sharing features with Brassicaceae, including bilocular fruits with a single strongly curved (likely campylotropous) seed in each locule, and a narrow septum or replum. Gyrogonites of a Charophyte green algae, most likely Chara, are also present at this locality; these records suggest shallow freshwater or oligohaline bodies of water were nearby. Previously described localities in the Tongue River Member, may be younger, and contain taxa not represented in Newell’s Nook, including Nordenskioeldia (Trochodendraceae), Celtis (Cannabaceae), Aesculus (Sapindaceae), and cornalean taxa (Amersinia, Browniea, Davidia). Kingsboroughia rostellata and Jenkinsella are recurring elements among Paleocene carpofloras. Newell’s Nook shares elements with both younger and older Paleocene localities at Almont, North Dakota, Sand Draw, Wyoming, and Littleton, Colorado. Together with the Newell’s Nook flora, these localities forge a clearer picture of Paleocene fruit diversity in western North America.

Habitat-Driven Evolution of Seed Dispersal Strategies in Onion Grasses.

McKenzie Carlson, undergraduate at the University of Washington; Maria Rottersman, undergraduate at the University of Washington; Ana Bedoya, graduate student at the University of Washington; William Brightly, graduate student at the University of Washington; Caroline Stromberg, faculty at the University of Washington

mck2022@uw.edu

Seed dispersal is a crucial stage in the plant lifecycle, with broad influences on community composition, ecological succession, and response to climate change. Given its importance, documenting the factors that contribute to the evolution of varied dispersal modes and promote convergence on specific dispersal strategies is vital to understanding plant ecology. Here, we explore whether habitat is among these factors. Habitats vary in how they are distributed across space and time, which may influence which dispersal strategies are most successful. To investigate this relationship, we studied the genus Melica and its relatives in tribe Meliceae. These grasses are a useful case study, as they live in a range of habitats and have remarkably morphologically diverse dispersal structures (diaspores). Additionally, among them are several distinct shapes related to wind dispersal, a strategy that has apparently evolved several times in the tribe. We tested the hypothesis that evolution in morphological traits associated with seed dispersal is correlated with changes in habitat. In particular, we hypothesize that the evolution of wind dispersed seeds follows transitions into open or disturbed habitats. A total of 170 diaspores, representing 28 species (14 Melica and 14 outgroup) were collected from herbarium vouchers. We assessed wind dispersal potential by quantifying falling velocity. Falling velocity and average plant height were used to compute dispersal kernels from which we extracted the expected wind dispersal distance for the median diaspore for each species. Habitat data were obtained for each species using georeferenced occurrence records and global landcover maps. Phylogenetic relationships of the sampled Meliceae were inferred under Bayesian inference using nuclear and plastid markers. Our results indicate that higher wind dispersal potentials (but not predicted wind dispersal distance) are associated with greater degrees of anthropogenic disturbance and suggest that changes in habitat have occurred in conjunction with changes in seed dispersal traits.

On the use of databases in paleobotanical research: triumphs, pitfalls, and good and bad examples.

Andrew, Simpson, Smithsonian Institution; Vera, Korasidis, Smithsonian Institution

andy.g.simpson@gmail.com

Online databases of botanical records of living and fossil plants provide opportunities for researchers to conduct broad-scale analyses without the time, funding, permission, and manpower constraints required for fieldwork or new analysis from existing collections. However, the results of studies reliant upon databases are only as trustworthy as the data incorporated. Paleobotanical data are often different from neobotanical data in several notable ways: first, organs are often preserved separately, and consequently given separate taxonomic names. Incorporating each organ individually in measures of diversity could lead to overestimations of diversity in epochs/successions where the taxa have been well described. Second, paleobotanists are more confident assigning younger (i.e., Cenozoic) fossils to living taxa than older (i.e., Palaeozoic or Mesozoic) fossils; consequently, older fossils often have different names from morphologically identical younger fossils. Modern paleobotanists are also less eager to assign fossils to living genera based purely on gross visual similarity than past paleobotanists. Third, again because of uncertainty surrounding morphology, similar fossils collected from different regions representing the same plant, can be given different names. We here review selected studies from the published literature that use the Paleobiology Database (PBDB) as a source of paleobotanical data in synthetic analyses. Some of the authors of these papers applied appropriate caution concerning the aforementioned pitfalls and thus produce trustworthy results. Others do not consider the biases imposed by paleobotanical data and take the PBDB records at face value, and thus produce misleading results, among them extinction and radiation events that are not real, temporal ranges of fossil taxa in excess of what is probable, and other issues. We summarize problems that arise from these misunderstandings of paleobotanical data, and make suggestions for future scientists, both for neobotanists interested in using paleobotanical databases, and for managers of databases containing paleobotanical data.

Using Angiosperm Foliar Tooth Morphology as an Aid to Fossil Leaf Identifications.

Patrick F. Fields*, OJ Smith Museum of Natural History, College of Idaho, Caldwell, ID 83605 and 5349 North Canal Road, Dimondale, MI 48821

patrickffields@wowway.com

In 1973, Hickey and Wolfe (1976) presented the concept of different Angiosperm leaf tooth types as a tool towards taxonomic identification. The implications for paleobotanical leaf identification were readily apparent, particularly for later Cenozoic plants, and for mid-higher latitude & elevation plants, where the percentage of non-entire leaf margins is greater. They recognized 14 tooth types, distinguished by the number and strength of veins entering a tooth, the presence and shape of terminal glands, and the overall shape. Named primarily after a prominent plant family that bore each tooth type, they recognized: Begonoid, Chloranthoid, Cucurbitoid, Cunnonoid, Dilllenoid, Malvoid, Monimioid, Platanoid, Rosoid, Salicoid, Spinose, Theoid, Urticoid, and Violoid tooth types. Unfortunately, these were not in a format that was particularly useful for fossil leaf identification. As part of the Leaf Architecture Working Group (1999) and its update Hickey (2009) de-emphasized the taxonomic affinities of teeth (in favor of morphology) by introducing 10 terms to describe angiosperm tooth apical termination types: Cassidate, Foraminate, Mucronate, Papilate, Setaceous, Simple, Spherulate, Spinose, Tylate, and Nonspecific. Only Spinose was the same in both groups. Since each system has value, the present paper uses the original 14 tooth types and integrates information in a taxonomic context using multiple sources of information, with cross-correlation, illustrations, and taxonomic tables. Thus, this article can provide multiple cross-referenced features that may support or eliminate potential identifications. Once published, it is hoped that this compilation represents a more functional format for paleobotanists. The author invites feedback.

Fossil flora of the mid-Eocene Kishenehn Flora, northwestern Montana, USA.

MacKenzie, Smith, University of Florida Department of Biology, Florida Museum of Natural History; Steven, Manchester, Department of Biology, University of Florida Department of Geosciences, Florida Museum of Natural History; Selena, Smith, University of Michigan Department of Earth and Environmental Sciences, University of Michigan Museum of Paleontology

mackenziesmith@ufl.edu

Lacustrine shales of the Kishenehn Formation of northwestern Montana provide an important window to the local mid-Eocene (Lutetian) ecosystem including evidence from insects, molluscs, vertebrates and plants. However, little has been published on the macroflora which includes abundant compressed fruits and seeds as well as foliage. Here we provide a preliminary survey, with particular attention to the reproductive remains from the Middle Fork Region which include Equisetaceae, Cupressaceae, Pinaceae, Betulaceae, Brassicaceae, Eucommiaceae, Juglandaceae, Oleaceae, Platanaceae, Rutaceae, Salicaceae, Sapindaceae, Simaroubaceae and Ulmaceae. We compare the Kishenehn ecosystem to the older Green River Formation of Wyoming, Utah and Colorado, various Early and mid-Eocene localities of the Okanogan Highlands of Washington and British Columbia, and the Eckfeld Maar of similar age in Germany.

New reproductive structures of Cunoniaceae tribe Cunonieae from the early Eocene Laguna del Hunco flora, Chubut, Patagonia, Argentina.

Theodore, Matel, LH. Bailey Hortorium, Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, USA; Maria A., Gandolfo, LH. Bailey Hortorium, Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, USA; Elizabeth J., Hermsen, Paleontological Research Institution, Ithaca, NY 14850, USA; Peter, Wilf, Pennsylvania State University, Dept. of Geosciences, University Park, PA 16802, USA.

tpm66@cornell.edu

The early Eocene (~52 Ma) Laguna del Hunco flora from Chubut Province, Patagonia, Argentina, has provided key insights into the history of iconic Southern Hemisphere plant taxa, among them Agathis (Araucariaceae), Papuacedrus (Podocarpaceae), Gymnostoma (Casuarianaceae), Eucalyptus (Myrtaceae), and the families Proteaceae, Winteraceae, and Cunoniaceae. Within Cunoniaceae, fruits of Ceratopetalum (tribe Schizomerieae) have previously been described from the flora. Here, we present new reproductive macrofossils with morphological affinities to the extant genus Weinmannia of tribe Cunonieae. The specimens include multiple reproductive axes bearing flowers and fruits, as well as dispersed capsules. Morphological similarities that link the fossils to extant Cunonieae include racemose reproductive axes with acropetal and synchronous flower and fruit maturation; dehiscent, bicarpellate, and syncarpous capsules; persistent, decurrent styles; and four- or five-merous perianth whorls. The combination of a seed-bearing replum in the capsule, septicidally dehiscent capsules, and a persistent 4-5-merous calyx links the specimens to the genus Weinmannia. These specimens represent the first and oldest record of Cunonieae in South America based on reproductive macrofossils, and they provide strong evidence that at least two tribes of Cunoniaceae—Cunonieae and Schizomerieae—had already diversified by the early Eocene. Weinmannia is the most speciose extant genus of family in South America. Globally, it comprises approximately 200 species and is widely distributed in the Neotropics, temperate South America, subtropical and tropical Indian Ocean islands (Comoros, Madagascar, and the Mascarenes), Malesia, and the South Pacific. Therefore, the presence of fossils with affinities to Weinmannia connects the Laguna del Hunco paleoflora in West Gondwana to multiple modern biogeographic regions, presumably through combinations of plate movements and oceanic dispersals.

Reevaluation of the Cenozoic Impression Record of Psudotsuga Carr. in Western North America.

Jeffrey A. Myers, Western Oregon University Department of Earth Science, Western Oregon University, Monmouth, OR 97361, myersj@wou.edu; Diane M. Erwin, and Howard E. Schorn, University of California, Berkeley, Museum of Paleontology, 1101 Valley Life Sciences Bldg., Berkeley, CA, 94720

jeff.fossil25@gmail.com

Fossil occurrences of Pseudotsuga (Pinaceae) have been reported from as early as the Cretaceous from dozens of localities in western North America and Eurasia. Reevaluation of the impression fossil record of Pseudotsuga in western North America finds that the majority of specimens identified as Pseudotsuga are either incorrectly identified or too poorly preserved to be identified. Only eight occurrences have been confirmed at present, principally from winged seeds, although dispersed, but co-occurring, foliage, foliated and defoliated axes, and ovulate cones are consistent with Pseudotsuga, as well. The verified fossils form two groups and four morphotaxa. Ovulate cones and winged seeds of Pseudotsuga laticarpa Lakhanpal from the ~ 32 Ma Rujada Flora, Oregon, and P. cassiana (Axelrod) Schorn from the ~ 13 Ma Trapper Creek Flora, Idaho, resemble those of the extant P. macrocarpa (Vasey) Mayr. in cone and seed dimensions. Ovulate cones and winged seeds of Pseudotsuga taxifolioides Arnold from the 13 Ma Trout Creek Flora, SE Oregon, and P. sonomensis Dorf from the ~ 3 Ma Neer’s Hill locality of the Sonoma Volcanics, resemble the extant P. menziesii (Mirb) Franco in cone and seed dimensions. These limited initial data suggest that the big-coned form of Pseudotsuga originated in the humid-mesic, microthermal coastal Northwest during the early Oligocene, and that the small-coned form first appeared in the middle Miocene of the interior west, under cooler, summer dry climatic conditions. Initially both forms represented sub-dominant components of broadleaved vegetation. Modern Douglas Fir-dominated coniferous forests of the coastal Pacific Northwest did not develop until the Pliocene, in response to the expansion of summer drought, as the North Pacific Gyre strengthened and cooled with the growth of north polar ice.

Beautifully preserved Fruits and seeds of Euphorbiaceae from the Oligocene of Peru investigated by micro-CT scanning and light microscopy.

Ashley Hamersma, University of Florida; Steve Manchester, University of Florida; Fabiany Herrera, Chicago Botanic Garden

ahamersma@ufl.edu

Three-dimensionally preserved fruits and seeds of “Jatropha” tertiara Berry from the early Oligocene of western Peru have been reinvestigated based on type material supplemented by more recently collected specimens. Specimens were studied with micro-computed tomography scanning (micro-CT) and reflected light microscopy in order to fully characterize both external and internal features. For comparison we surveyed fruits of more than 50 extant genera of Euphorbiaceae by micro-CT scanning. Fossil fruits are prolate trilocular capsules that are hexagonal in cross section with prominent loculicidal and septicidal keels; one seed per locule, and anatomically thin-walled. The seeds are ovate in dorsiventral view, lenticular in cross section and terminated by a prominent, broad caruncle about half the length of the seed body. The large size and 6-keeled aspect of the fruit distinguishes this fossil from extant species of Jatropha. Similarities to other genera, particularly with some species of Manihot, indicate likely affinities with the Crotonoid clade, but the particular morphology of the fossil material is not well aligned with any observed modern genus.The relatively large, uniquely preserved caruncles on these seeds, comprising about ⅓ of the full seed length, indicates that ant dispersal likely evolved within the Crotonoid clade at least since the Oligocene. Although we reject the former assignment of this fossil to Jatropha, this work confirms the assignment to the family Euphorbiaceae. This species grew together with other members of Annonaceae, Arecaceae, Leeaceae, Malvaceae, Humiriaceae, Icacinaceae, Rutaceae, and Vitaceae as confirmed taxonomic groups present in the Oligocene Belén flora. This improves our understanding of this conspicuous component of the Belén carpoflora, contributes to our broader understanding of the biogeographic history of the Euphorbiaceae, and calls for caution in calibrating the divergence time of Jatropha.

Where did they come from, where did they go: examining niche conservatism through time in a primarily tropical plant lineage.

Zack, Quirk, Department of Earth & Environmental Sciences, University of Michigan; Selena, Smith, Department of Earth & Environmental Sciences, University of Michigan, Museum of Paleontology, University of Michigan; R. Paul, Acosta, Department of Earth & Environmental Sciences, University of Michigan

zquirk@umich.edu

Many plant and animal species will be greatly affected by anthropogenic climate change in the coming years, which raises the question of whether climatic niches of species change. While the fossil record has been used to test for niche conservatism (organismal preservation of original ecological traits over time) in fossil invertebrates to determine how the environmental constraints for these organisms have changed through time compared to the modern, niche conservatism is largely unexplored in plants. In this study, we aim to test if climatic niche constraints have remained consistent through time by characterizing climate niches of living ginger plants (Zingiberaceae) and comparing them with the paleo-niches reconstructed based on fossil distribution. If ginger niches have remained conserved through time, then we can use extant ginger climate regimes for reconstructing past climates. To test this, we used ArcGIS Pro to calculate the modern climate niches of Zingiberaceae and its four subfamilies from living occurrence data and bioclimatic variable data, namely cold month mean temperature (CMMT), mean annual temperature (MAT), and mean annual precipitation (MAP). Fossil ginger occurrences were collected from the literature, with the distribution mapped using PALEOMAP. Based on CMMT and MAT, only one subfamily is deemed as tropical (CMMT>18oC) while the rest are subtropical (CMMT<18oC; MAT>16oC). The fossil ginger distribution shows a Cretaceous presence in both higher latitudes and the tropics, but then remains only in those upper latitudes for the rest of the Cenozoic fossil record. With impending paleoclimate modeling data, we expect to confirm that the climatic conditions for these upper latitude fossil gingers was similar to those of the modern day, as much of the Cenozoic had expanded (sub)tropical climates. If this assertion is correct, then we can use fossil ginger occurrences for reconstructing past climates.

Genome size evolution in early land plants

Astrid Odé BSc., Utrecht University; Dr. Paul Kenrick, Natural History Museum London; Prof. Dr. Friederike Wagner-Cremer, Utrecht University

a.ode@students.uu.nl

Polyploidy is thought to be a driver of plant evolution, which is characterized by repeated cycles of whole-genome duplication events, followed by re-diploidization. A key event in this history was the emergence of the vascular plants, the tracheophytes, that evolved after plant terrestrialization about 500 million years ago. By using the universal positive correlation between cell size and genome size, the genome size of early land plants can be estimated. To investigate the relationship between polyploidy, genome size, and early land plant evolution, Lomax et al. (2014) estimated the genome size of the early Devonian lycophyte Asteroxylon mackiei by using guard cell length of the stomata as proxy. They found it to have an exceptionally large genome size, based on a mean guard cell length of 73 μm. This literature research, however, needed to be supplemented and verified with real fossil data. Therefore, in this research, guard cell length of fossil Asteroxylon mackiei samples from the Rhynie Chert, located at the Natural History Museum London, were used as proxy for its genome size. The estimation is calibrated with Asteroxylon mackiei’s closest living relatives with known and increasing genome sizes from the Kew C-DNA database: Selaginella moellendorffii, Diphasiastrum digitatum, Lycopodium obscurum, and Huperzia lucidula. The mean guard cell length of Asteroxylon mackiei was found to be 59.8 μm, which corresponds to a genome size of 8.5 pg. This is within the upper range of living lycophytes, but not exceptionally large. Therefore, the mean guard cell length of 59.8 μm should be used instead of Lomax’s 73 μm to estimate Asteroxylon mackiei’s genome size. The large variance in guard cell length and the presence of two morphotypes of stomata support the hypothesis that multiple (ploidy) species of Asteroxylon mackiei could have existed.

A paleotemperature thermometer for the Northern Andes based on C3/C4 grass phytoliths

Camilla, Crifò, Institut des Sciences de l’Évolution de Montpellier (ISEM), EPHE, PSL Research University, Université de Montpellier, CNRS, IRD, Place Eugène Bataillon, CC 065, 34095 Montpellier, France; Juan Carlos, Berrio, School of Geography, Geology and Environment, University of Leicester, University Road, Leicester LE1 7RH, UK ; Arnoud, Boom, School of Geography, Geology, and the Environment, University of Leicester, University Road, Leicester, LE1 7RH, UK; Diego, Giraldo-Cañas, Herbario Nacional Colombiano, Instituto de Ciencias Naturales, Universidad Nacional de Colombia, Avenida Ciudad de Quito # 55-31, Barrio Nicolás de Federmann, Bogotá D.C., Colombia ; Laurent, Bremond, , Institut des Sciences de l’Évolution de Montpellier (ISEM), EPHE, PSL Research University, Université de Montpellier, CNRS, IRD, Place Eugène Bataillon, CC 065, 34095 Montpellier.

camilla.crifo@umontpellier.fr

We study phytolith assemblages collected from open vegetation plots along an elevation gradient in the Northern Andes (Colombia) to develop a transfer function for paleotemperature. To do so, we used the phytolith-based Climatic Index (Ic), which is based on the abundance of C4 short cell grass phytoliths over the sum of short cell grass phytoliths (GSSCP). In fact, in the Andes the distribution of C4 and C3 grasses follows an elevation gradient, mainly associated with a temperature gradient. To evaluate the accuracy of phytolith assemblages to reflect C4 vs. C3 grass abundance in the vegetation, we compared phytolith data with semi-quantitative estimates of C4 vs. C3 grass abundance in the plots. To further evaluate the Ic index as a proxy for C4 vs. C3 grass abundance we compared it with the ∂13C isotopic signature of the samples, which represents an independent proxy for C4 vs. C3 vegetation. We then developed a transfer function for MAT based on the Ic. We found that 1) GSSCP assemblages correctly estimate C4 vs. C3 grass abundance in the vegetation; 2) the Ic index outperforms the ∂13C isotopic signature in estimating C4 vs. C3 grass abundance, even in open vegetation types; and that 3) our model correctly predicts MAT based on the Ic index. Thus, our findings provide a new calibrated tool to improve paleotemperature reconstructions in the northern Andes. Indeed, several Andean basins are currently under study and provide a unique opportunity to document the uplift history and linked climate of this region (because sedimentation in these basins did not cease as uplift progressed). Thus, our phytolith-based proxy can help reconstruct paleotemperatures in the Andes, at least since the emergence and spread of C4 grasses in the region.

Assessing limitations of community-scale inferences of leaf mass per area estimates made from fossil leaves

Ena Chen, Alexander Lowe, Caroline Strömberg, Department of Biology, University of Washington

qchenf01@uw.edu

Leaf mass per area (LMA) is an important leaf functional trait that reflects the extent of structural investment in a leaf and is commonly used by paleobotanists to reconstruct past ecosystems. It is one of the principal traits driving the leaf economic spectrum, with plants ranging from having fast resource acquisition, high relative growth rates, low leaf life spans (e.g., deciduousness), and low leaf mass per area at one end, to having the opposite traits on the other end of the spectrum. Because leaf mass cannot be obtained from fossil leaves directly, an easy-to-measure proxy to estimate LMA from woody ‘dicot’ leaves was developed by Royer et al. (2007). This proxy takes advantage of the biomechanical relationship of petiole width relative to leaf area (here called ‘petiole stoutness’), and LMA, with a higher LMA necessitating a wider petiole to support that leaf area. An unsolved problem with the metric is that the standard error of the petiole stoutness and LMA relationship is large, which limits interpretations of community-level trends and complicates the classification of a fossil taxa's leaf habit. We address this by utilizing the community-level dataset of modern leaves from Peppe et al. (2011) to test for similarities in the community-level distributions of estimated (from petiole stoutness) and measured (from leaf mass) LMA values, and the variance of both among different climate types. We also calculate the percentage of taxa where leaf habit was correctly inferred by estimated LMA following the guidelines of Royer et al. (2007). This study provides critical information on the extent to which LMA estimates from fossil leaves can be used to reconstruct ancient plant community ecology.

An open vegetation-plot database for Southeast Asia: tool for ecology, conservation, and paleo-conservation

Edward, Spagnuolo, Pennsylvania State University, Dept. of Geosciences, University Park, PA, 16802, USA; Peter, Wilf, Pennsylvania State University, Dept. of Geosciences, University Park, PA, 16802, USA; Robert, Kooyman, Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia, Research Centre for Ecosystem Resilience, Royal Botanic Gardens, Mrs Macquaries Road, Sydney, New South Wales 2000, Australia

ejs5902@psu.edu

Southeast Asia is known for its immense biodiversity, disastrous levels of forest clearing, and elevated extinction-risk. Vegetation plots are a standard tool used to analyze forest dynamics and correlate community structure to biotic and abiotic gradients. Plot-based ecological analyses of Southeast Asian forests have proven invaluable for understanding floristic composition and community dynamics; however, raw plot data is often left unpublished or remains unconsolidated across a wide variety of regional literature. To address the need for open-access floristic data, we are collecting published inventories to construct a vegetation-plot database of Southeast Asia. This effort will help evolutionary biologists, conservation biologists, macroecologists, and paleobotanists (with interests in living relatives of fossil lineages) to study vegetation dynamics across an anthropogenically endangered region. Our survey, focused on Malesia and Indochina, includes plot-based floristic data or small-scale species checklists from Laos, Cambodia, Vietnam, Myanmar, Thailand, Malaysia, Singapore, Indonesia, Philippines, Brunei Darussalam, Timor-Leste, and Papua New Guinea. So far, we have found over 285 papers that contain species-level plot data, with 45% containing abundance measurements. More than half of all plots are in Borneo and mainland Asia, and most sample lowland dipterocarp-dominated forests. We are using Tabula (https://tabula.technology/) to extract plot data from published tables or manually inputting into Excel, then using the WorldFloraR module (Kindt, 2020, Appl. Plant Sci. 8, e11388) to standardize plant names to the World Flora Online taxonomic backbone (http://www.worldfloraonline.org/downloadData). The diverse potential uses of the dataset include paleoecological studies of ancient plant lineages that are known as fossils and are also extant in Southeast Asian rainforests. Plot analyses will allow fine-scale quantification of the influence of abiotic variables on the dominance distributions of Gondwanan-sourced and other ancient lineages, thereby providing new insights into how ancient forests may have functioned, while informing contemporary efforts to conserve evolutionary heritage.

Rapid scoring and morphotyping of fossil leaf floras from large image libraries using Adobe Bridge

Gabriella Rossetto-Harris, Penn State University; Peter Wilf, Penn State University; Elena Stiles, University of Washington; Xiaoyu Zou, Penn State University

gur53@psu.edu

Whole-flora analyses using fossil leaf morphotypes yield critical paleoecological information and provide a descriptive foundation for systematic studies. Digital image libraries are widely used to complement work on physical specimens. However, the process of coding and sorting hundreds of specimens digitally with extensive image libraries is often a cumbersome process, and most workflows do not link character data directly to the images. The free desktop application Adobe Bridge, a visual file browser and management system, is ideal for efficiently organizing and viewing specimen image libraries, while simultaneously producing detailed, searchable character data that is embedded in each image. We created a data dictionary of the characters defined in the Manual of Leaf Architecture (B. Ellis et al. 2009) to be used as a Bridge keyword set. In Bridge, customizable keywords for taxonomically informative characters can be applied directly and reversibly to individual full resolution images, without resampling or platform switching. Once keyworded, the user can easily filter, organize, visually compare, and cross-validate large collections of images using any combination of characters and view them with several zoom tools. The integrated Adobe Camera Raw application allows for reversible image adjustments to prepare the same images directly for publication. The assigned keywords can be extracted to write descriptions or exported to a CSV file, and accompanying code, in progress, formats the data into a character matrix for analysis. The keyword set and code will be made available on an open-access platform. This workflow mimics the in-person experience of inspecting, sorting, and flagging specimens in museums. We find that it drastically reduces the in-person collections time needed while expediting comparisons of collections from different museums and of fossil and modern comparative material. The same approach can be easily customized for other types of fossils or for any visual sorting task using image libraries.

Large Slabs, Slim Margins and Unbiased Collecting: Getting the Most from Your Outcrop

Gregg Wilson, Stonerose Interpretive Center

cemihunter@yahoo.com

The Stonerose Interpretive Center (SRIC) in Republic, Washington has been overseeing an outcrop of the Tom Thumb member of the Klondike Mountain Formation for 30 years. A road cut at the north end of town, known as Boot Hill, exposes an Eocene lake bed with a very diverse plant and insect assemblage exquisitely preserved in very fine volcanic sediments. After decades of citizen science, involving relatively unsupervised digging in the quarries mainly by tourists and school children, techniques for more efficient use of the strata were sought. This report details methods used to improve collection techniques, reduce bias in collection protocols, and prepare specimens for scientific study. A smaller quarry at the south end of town, the Corner Lot, was entirely designated as a stratigraphic dig and the methods utilized to recover the largest intact blocks are detailed here. When fossils are recovered, they often retain matrix which can obscure important details. For leaves, the removal of this matrix in the lab presents a number of difficulties not often encountered in vertebrate or invertebrate fossil prep. Techniques learned while prepping leaves at the Burke Museum in Seattle are illustrated. Collecting the largest, most perfect or visually appealing fossils can be very rewarding but often relegates important and rare specimens to the discard pile. Unbiased collecting, here illustrated by the SRIC Unbiased Insect study, mitigates this problem and provides the most efficient utilization of the strata. These methods have improved our recovery of intact, larger leaves, informed us of the associations between various flora and fauna deposited at the same event horizon and increased our retention of less obvious but still important fossils. We hope to also use these techniques at Boot Hill in the future and encourage other fossil sites to follow suit.

Late Cretaceous plant remains from the Monos Formation of Cuba

Julian E. Correa-Narvaez, University of Florida, Florida Museum of Natural History, Dickinson Hall, 1659 Museum Rd, Gainesville, FL, 32611-7800, USA; Lazaro Vinola, University of Florida, Florida Museum of Natural History, Dickinson Hall, 1659 Museum Rd, Gainesville, FL, 32611-7800, USA

j.correanarvaez@ufl.edu

The origin of some terranes in the West Indies can be traced back to the middle-late Cretaceous with the formation of a volcanic arc of islands in the eastern-leading margin of the Caribbean plate. This arc of islands likely served as a corridor of biotic exchange between North and South America between the late Cretaceous and the early Paleogene. Cuba, the largest island of the Antilles, has a rich paleontological history, with numerous vertebrate and invertebrate fossils known. However, fossils of terrestrial origin from the Late Cretaceous are poorly known for these paleo-communities and, in particular, the macrofossil flora from this time period. The exploration of three localities near the town of Rodas in central Cuba (La Presa Damjí, Aguaditas, and Puente Potrerillo) led to the discovery of numerous macrofossils from sediments of the Monos Formation (Late Campanian-Early Maastrichtian). The finding includes remains pterosaurs, terrestrial gastropods, decapod crustaceans, and several plants– the last ones being the focus of this presentation. The Monos flora includes several fragments of wood (probably coniferous), scale leafy-shoot casts (cupressaceous) and fruit mold-casts (Lauraceae affinity). Increased sampling and studies are needed to illuminate this important flora.

Variation in Grass Seed Dispersal in Tropical Savannas

Maria Rottersman, University of Washington Department of Biology; William H. Brightly, University of Washington Department of Biology; Matheus E. Bianconi, Department of Animal and Plant Sciences University of Sheffield; Caroline A. E. Strömberg, University of Washington Department of Biology

mgrottersman@gmail.com

Savannas of the neotropics and paleotropics, although similar in their C4 grass dominated understory, possess distinct evolutionary and environmental histories which have contributed to structural differences between these communities. These differences are likely to have major impacts on the ecology of each region, including seed dispersal processes. Seed dispersal is an important component of the plant lifecycle, and angiosperms have evolved multiple ways of dispersing their progeny. We test the hypothesis that grasses in open habitats are more likely to favor wind dispersal (anemochory) and that grasses in areas with dense megafauna are more likely to favor animal dispersal (epizoochory and endozoochory) by comparing morphological traits of ecologically dominant grasses of the tropical savannas of Venezuela, Cerrado (sensu stricto) of Brazil, and the Serengeti region in Tanzania. Higher canopy cover in regions of neotropical savannas relative to paleotropical savannas lead to the prediction that anemochory is favored in the latter. The abundance of megafauna in the Serengeti, particularly grazing ungulates, suggests that epizoochory and endozoochory are more prominent in paleotropical savannas than in neotropical savannas, which are generally lacking in megafauna. To test our hypotheses, we sample dispersal structures (diaspores) from herbarium specimens. To estimate wind dispersal ability, falling velocity as measured by high-speed video is used as a proxy, with lower falling velocity indicating adaptation to anemochory. Diaspore surface roughness is quantified to measure degree of epizoochory, and diaspore mass indicates degree of endozoochory. Data are considered in a comparative framework to account for the influence of phylogeny. Contrary to predictions, preliminary results suggest that on average, anemochory potential is higher among grasses of neotropical savannas, and that neotropical savannas have a higher spread of falling velocities. The latter may be due in part to the ecologically diverse subformations of Cerrado, resulting in different dispersal mechanisms by subregion.

Examining Paleoclimate Across the Cretaceous-Paleogene (K/Pg) Boundary in Northeastern Montana

Paige K., Wilson, Department of Earth and Space Sciences, University of Washington; Allison, Phillips, School of Environmental and Forestry Sciences, University of Washington; Caroline A.E., Strömberg, Department of Biology, University of Washington; Gregory P. Wilson Mantilla, Department of Biology, University of Washington

wilsonp2@uw.edu

The Cretaceous-Paleogene (K/Pg) boundary is marked by a major mass extinction resulting in global biotic turnover, notably the extinction of non-avian dinosaurs. Causal mechanism(s) of the mass extinction is believed to have been bolide impact, volcanism, climate change, or some combination thereof. The Hell Creek Area in northeastern Montana contains some of the most well-studied vertebrate localities recording this mass extinction; however, very little is known about floral changes in this area. Plant fossils lend unique insight not only into the fate of vegetation at the K/Pg boundary, but also into the climate conditions in the lead up and immediate aftermath of the mass extinction. In this study we present preliminary results using a series of floras spanning approximately 2 m.y. around the K/Pg boundary to estimate paleoclimate conditions in this critical interval. We utilize the digital leaf physiognomy (DiLP) method in combination with univariate methods (i.e., leaf margin and area analyses) to estimate mean annual temperature and precipitation. We compare these preliminary results to estimates of paleoclimate derived regionally (floral studies in North Dakota) and locally (clumped isotope paleothermometry) to evaluate and compare with our results. We investigate whether this local record resolves the same latest Cretaceous warming interval found in previous paleoclimate studies in the Hell Creek area. Further, we aim to test the hypothesis that this warming interval is coincident with changes in plant communities (e.g., a rise in thermophilic taxa) and may have exacerbated the extinction magnitude at the K/Pg boundary. Information about paleoclimate conditions across the K/Pg boundary are crucial for resolving and interpreting patterns of terrestrial biotic community change during this interval.

Floral changes during the late Paleozoic deglaciation of Australia: a network approach

R., Hayes, Department of Integrative Biology, University of California, Berkeley, UC Museum of Paleontology; Cindy, Looy, Department of Integrative Biology, University of California, Berkeley, UC Museum of Paleontology, UC & Jepson Herbaria

reilly_hayes@berkeley.edu

Despite the approximate latitudinal equivalence of the regions, glacial records from the Permian of western and eastern Australia exhibit an intriguing asymmetry. In western Australia complete deglaciation was achieved no later than the Sakmarian-Artinskian (~290 Ma, early Permian), while in eastern Australia recurrent glaciations persisted until the Wuchiapingian (~254.5 Ma, late Permian). Palynofloral data from basins across the continent capture floral responses to these disparate ice regimes, as well as the longer-term Permian transition from an icehouse to hothouse Earth. We here use successive bipartite palynological networks to investigate Australian vegetation dynamics throughout the Permian. These networks consist of two distinct node classes—taxa and localities—linked by edges representing occurrences of those taxa through space. A clustering algorithm delineates biogeographically-distinct vegetation assemblages according to the structure of each network. An algorithmically-derived timescale, built using the palynological samples and calibrated with 37 high-precision U-Pb CA-TIMS dates, provides temporal control over the analysis. Because this timescale allows us to gauge the contemporaneity of each pair of palynological samples in our data set, we maximize the temporal precision of the analysis by building a succession of discrete networks representing separate time slices of the Permian. The current data set consists of 21,123 occurrences of 438 unique palynological taxa spread across 71 sections from Permian Australian basins. This volume of fossil data allows the networks to provide insight into the ecological and biogeographic evolution of high-latitude floras during the collapse of the Earth’s penultimate icehouse.

The hydroclimatic and paleoenvironmental response to warming in the southwestern US: A case study of the Middle Miocene Climate Optimum

Siânin D. Spaur, Colorado State University; Jeremy K. Caves Rugenstein, Colorado State University; Daniel J. Koning, New Mexico Bureau of Geology and Mineral Resources, New Mexico Institute of Mining and Technology; Elizabeth L. Driscoll, Colorado State University; Scott Aby, Muddy Spring Geology

sianin.spaur@colostate.edu

Stable isotopes of inorganic carbonates are commonly used to reconstruct terrestrial paleoenvironments. We analyze the δ18O and δ13C of paleosol carbonates formed during the Mid-Miocene Climatic Optimum (MMCO; 17-14.5 Ma) near Española, NM, to study the effects of high pCO2 and warming on the hydroclimate and paleoenvironments of the southwestern United States. Climate models attempt to predict the hydroclimate response to modern climate change in the region, but geologic data is needed to constrain these predictions. The MMCO serves as a potential analogue to understand how southwestern US ecosystems and climate will respond to high atmospheric pCO2. Today, the region receives wintertime moisture from the El Niño Southern Oscillation (ENSO) and summertime moisture from the North American Monsoon; these sources are isotopically distinct, allowing the δ18O of soil carbonates to reflect the relative importance of each moisture source. The Española Basin has a continuous sediment record throughout the mid-Miocene, abundant carbonates allowing for a high-resolution terrestrial record of the MMCO, and a detailed faunal and floral record that can additionally inform paleoclimate and paleoenvironmental reconstructions. Preliminary data show a decrease in δ18O and 13C across the MMCO, which may support an increase in winter-time precipitation and plant productivity potentially driven by a strengthened ENSO. Floral and faunal data support a warmer, potentially wetter climate, perhaps driven largely by changes in winter-time precipitation. Axelrod and Bailey (1976) identified a Miocene-aged fossil sabal palm in the basin that suggested a mild winter climate, a mean annual temperature higher than modern, and a smaller seasonal temperature range than today. Faunal fossil assemblages indicate a mix of grazers and browsers and the existence of microenvironments supported by a range of vegetation with variable canopy heights. Our new stable isotope record provides important context regarding the mechanisms that supported these diverse floral and faunal communities.