CRETACEOUS
CLOSED
Embedded Files
CRETACEOUS
143.1 - 66 mya
The Cretaceous is a geological period that lasted from about 143.1 to 66 million years ago. Its name derives from the Latin creta, meaning "chalk", which is abundant in deposits from the later half of the period. It is usually abbreviated as K, for its German translation Kreide. The end of this period is marked by the Cretaceous-Paleogene extinction event, which also ends the Mesozoic era, which marks the last fossil appearance of non-avialan dinosaurs, pterosaurs and several lineages of marine reptiles, being caused by the impact of a large asteroid in the Gulf of Mexico, forming the Chicxulub crater.
The Cretaceous was first defined as its own distinct period by Belgian geologist Jean d'Omalius d'Halloy in 1822 as the Terrain Crétacé, using strata in the Paris Basin, named after the extensive chalk beds formed by calcium carbonate deposited by ancient shells of marine organisms, mainly the planktonic coccoliths, abundantly found in the late Cretaceous record of western Europe. Alcide d'Orbigny in 1840 divided the French Cretaceous into five stages: the Neocomian (~145 - 130 mya), Aptian (121.4 - 113.2 mya), Albian (113.2 - 100.5 mya), Turonian (93.9 - 89.8 mya) and Senonian (89.8 - 66 mya), later adding the Urgonian (130 - 121.4 mya) between Neocomian and Aptian and the Cenomanian (100.5 - 93.9 mya) between the Albian and Turonian.
The Cretaceous is now divided in two, the Early (143.1 - 100.5 mya) and the Late (100.5 - 66 mya) Cretaceous, with the very first stage being the Berriasian (143.1 - 137 mya); its lower base is hard to define, but it has been proposed that the first appearance of the alveolate Calpionella alpina, coinciding with the base of the eponymous Alpina subzone, could serve as the base of the whole Cretaceous period. The working definition for the boundary has often been suggested as the first appearance of the ammonite Strambergella jacobi, formerly placed in the genus Berriasella, but its use as a stratigraphic indicator has been questioned, as it does not correlate with the first appearance of C. alpina. After the Berriasian, there's the five other stages from the Early Cretaceous, the Valanginian (137 - 132.6 mya), Hauterivian (132.6 - 125.7 mya), Barremian (125.7 - 121.4 mya), Aptian (121.4 - 113.2 mya) and Albian (113.2 - 100.5 mya), as well as six stages from the Late Cretaceous, the Cenomanian (100.5 - 93.9 mya), Turonian (93.9 - 89.8 mya), Coniacian (89.8 - 85.7 mya), Santonian (85.7 - 83.6 mya), Campanian (83.6 - 72.2 mya) and Maastrichtian (72.2 - 66 mya), this last one having its upper boundary sharply defined by an iridium-rich layer found worldwide, associated with the Chicxulub impact, whose resulting crater currently covers part of the Yucatán Peninsula and Gulf of Mexico. This boundary marks the occurence of the Cretaceous-Paleogene extinction event (or K-Pg extinction event, for short) which, although devastating, had varying impacts across different clades of organisms. Photosynthesizing organisms were particularly affected as the soot created by the asteroid impact blocked the sunlight from reaching through much of the Earth's surface for years, causing collapses to the primary production of the planet's biosphere, composed mostly of phytoplankton and land plants, leading to the collapse of most organisms in higher trophic ranks that depended on these primary producers. Coccolithophores and mollusks were quite affected, such as ammonites, freshwater snails and bivalves (with the rudists disappearing completely from the fossil record), as well as the organisms that depended on these for survival. For example, ammonites may have been major components of the diets of mosasaurs, giant marine lizards that disappeared from the fossil record with the extinction. Animals that were omnivores, insectivores or necrophagous were less affected by the extinction as the resources required for their survival were more prevalent. In the water, the extinction appears to have affected organisms that lived more in the water column than in or near the benthos. During the period itself, however, life was thriving in conditions that were mostly characterized by high sea levels and warm climates, with large areas of continental shelf being underwater, creating vast portions of shallow sea for the proliferation of marine life. Extensive and thick chalk deposits formed during this time, and given their recency and uniqueness, they're very evident pieces of the period's geology found today across the globe. Around the middle part of the period, a number of dark anoxic shales were formed, such as the Mancos Shale in the western US, dated to about 110 to 80 million years ago. The north american continent, throughout parts of the Cretaceous, was relatively isolated from other landmasses, which resulted in its peculiar unique fauna at the time.
During the Cretaceous, the landmass containing modern South America, Antarctica and Australia ended up separating from Africa, forming the South Atlantic and Indian oceans, with the landmass containing India and Madagascar fully isolating from Africa later, at the late Cretaceous, around 80 million years ago. To the north of Africa, the Tethys sea continued to narrow. Paleobiogeography suggests that there was a shallow sea splitting Africa in two, during the Coniacian and Santonian stages (89.8 - 83.6 mya), connecting the Tethys with the southern Atlantic, judging by the distribution of bivalves at the time, indicating that parts of the central Sahara and central Africa were underwater at the time. Mid-ocean ridge activity—or rather, the circulation of seawater through the enlarged ridges—enriched the oceans in calcium; this made the oceans more saturated, as well as increased the bioavailability of the element for calcareous nanoplankton.
Palynological evidence suggests that the Cretaceous climate was divided into three broad phases: a Berriasian to Barremian warm dry phase (143.1 - 121.4 mya), a Aptian to Santonian warm wet phase (121.4 - 83.6 mya) and a Campanian to Maastrichtian cool dry phase (83.6 - 66 mya). The location of the Intertropical Convergence Zone (ITCZ) during the Cretaceous was roughly the same as in the present day. During the start of the Cretaceous, the opening of the north Atlantic seaway enabled the flow of cool water from the Boreal Ocean to the Tethys, continuing the cooling trend that was going on at the terminal Jurassic, which caused snowfalls and glaciation in higher latitudes. This was interrupted by the Weissert Event (~134.5 - 132.4 mya), caused by the igneous province going around the south american-african boundary, and later followed by the Faraoni Thermal Excursion (131 mya) and the Hauptblatterton Thermal Event (~125.7 - 123.5 mya). This marked the end of the Tithonian-early Barremian Cool Interval (TEBCI), which was then followed by the Barremian-Aptian Warm Interval (~123.5 - 118 mya). This was then followed by the Aptian-Albian Cold Snap (118 - 111 mya). This cold snap is associated with an arid period in the Iberian Peninsula. This cold period was swiftly substituted by a major hothouse period, the Mid-Cretaceous Hothouse (MKH), beginning shortly before the Leenhardt Thermal Event (110 mya) and the l'Arboudeyesse Thermal Event (109 mya), followed by the Amadeus Thermal Maximum (106 mya). After this, the Petite Verol Thermal Event (105 mya) occured. Around 94 million years ago, the Cenomanian-Turonian Thermal Maximum occured, the most extreme hothouse interval of the Cretaceous, characterized by very high sea levels. After this thermal maximum, temperatures cooled slightly only for another thermal maximum to occur, the Coniacian Thermal Maximum, some 87 million years ago. The temperature gradient between the poles and the tropics, during the MKH, was much gentler than nowadays, resulting in weaker global winds, which are major drivers of the ocean currents, resulting in less upwelling and more stagnant oceans. Surface ocean temperatures during the late Albian were pretty high, but interestingly not high enough to make the seawater hypersaline. On land, arid zones in the Albian regularly expanded northward in tandem with expansions of subtropical high pressure belts. After the MKH, there was the Late Cretaceous-Early Paleogene Cool Interval (LKEPCI), with a tendency of growing temperatures at the end of the Maastrichtian, with the volcanism of the Deccan Traps in India, leading to sea level rise, with the Tethys Sea, connecting tropical oceans east to west, contributing even more to this warming trend. Rafting by ice of stones into marine environments occurred during much of the Cretaceous, but evidence of deposition directly from glaciers is limited to the Early Cretaceous of the Eromanga Basin in southern Australia.
The Cretaceous was inhabited by an array of diverse flora, including the pteridosperms, or seed ferns, a collective term for enigmatic extinct seed plants with fern-like foliage, such as the Caytoniales, which were present in the period, with potential for the Corystospermaceae also being present. Angiosperm plants first appear as undoubted fossils in this period, but their exact origins are unclear, with molecular clock dating suggesting a Jurassic origin instead, and an evolutionary split from gymnosperms dating back to the Carboniferous.
During the Cretaceous, mammals were generally small, though quite relevant components of the global fauna, with cimolodont multituberculates sometimes outnumbering dinosaurs in some fossil sites. Basal forms of mammals, such as eutriconodonts, were common in the Early Cretaceous, but by the Late Cretaceous they seem to have mostly been replaced by multituberculates and therians in the northern hemisphere, and gondwanatheres and basal trechnotheres in South America. The apex land predators were archosaurs, especially dinosaurs, which reached the peak of their diversity in this period. The Early Cretaceous lagerstätten in Liaoning, China, represented by fossil formations such as the Yixian Formation, show detailed glimpses of mammalian and dinosaurian faunal diversity, including avialans. Some fossils of non-avialan dinosaurs from these strata are notable for preserving hair-like feathers, contextualizing us on their life appearance. A wider diversity of specific insect groups also is observed in the Cretaceous, including aphids, grasshoppers and wasps. Choristodere reptiles, which first appear as fossils in the Jurassic, reach the peak of their diversity in Asia, during the Early Cretaceous, with long-necked forms such as Hyphalosaurus and gharial-like neochoristoderes, possibly evolving in the regional absence of neosuchian crocodyliforms. By the Late Cretaceous, the neochoristodere Champsosaurus was widespread and common in North America. Due to the warm intervals that allows the polar regions to be hotter, these reptiles easily conquered the high latitudes at the time.
In the oceans, teleost fish and sharks, including rays, diversified immensely, marking their future success following the end of the Cretaceous period, but during the period itself they were actively coexisting with an array of unique and characteristic marine reptiles that dominated the seas.
main source: Wikipedia
A Earth map reconstruction, some 95 mya.
SUGGESTED SUBMISSIONS
(this space will be reserved to catalogue submissions done for this contest, simply for people to get a sense of what other people are working on)
Species (singular species submissions)
Species (singular species submissions)
Name: Parasisonia insolitum
Creator: baekjimin458
Size: 1.2 to 1.6 meters tall
Location: North America (Hell Creek Formation)
Time period: 68 - 66 mya
Clade: Tracheophytes, Eutracheophytes, Euphyllophytes, Megaphylls, Radiatopses, Lignophytes, Spermatophytes, Gymnospermae, Bennettitales, Williamsoniaceae, Parasisonia
Parasisonia insolitum is an enigmatic species of a monotypic genus of Bennettitales (cycadeoids) that possibly belongs to the Williamsoniaceae family, but their relationship with other members are unknown. This williamsoniacean species is endemic to (only found on) Hell Creek, during the late Maastrichtian around 68 to 66 million years ago until the K-Pg mass extinction event.
The characteristics of Parasisonia insolitum are woody shrubs and has scaly pinnates. However, their ecology was very much different from other williamsoniacean members, indicated by a lack of roots and loss of photosynthesis on the plastomes. This most likely suggests it to be a parasitic plant that is convergently similar to our timeline's modern day corails (Parasitaxus usta) from New Caledonia. Also its morphological characteristics slightly resembles those of Wielandiella known from fossils from the latest Triassic to Jurassic, despite not being related to it at all. Parasisonia insolitum are monoecious plants (plants that present both male and female genitals) that have unique crown-like male "flowers" with 12 petals; the female "flowers" were just as similar as those of other williamsoniacean members, but has a sweet potato-like morphology.
Name: Monatasimia dendroscanderum
Creator: larpbat656
Size: 60 centimeters long
Location: North America (Hell Creek Formation)
Time period: 67 - 66 mya
Clade: Unknown
No description given.
Name: Sacculusorex arctous
Creator: AlDodo
Size: 25 centimeters long (including tail)
Location: North America, Canada
Time period: 66 mya
Clade: Synapsida, Pelycosauria, Eupelycosauria, Metopophora, Haptodontiformes, Sphenacomorpha, Sphenacodontia, Pantherapsida, Sphenacodontoidea, Therapsida, Eutherapsida, Neotherapsida, Theriodontia, Eutheriodontia, Therocephalia, Cynodontia, Epicynodontia, Eucynodontia, Probainognathia, Prozostrodontia, Mammaliamorpha, Mammaliaformes, Mammalia, Theriimorpha, Theriiformes, Allotheria, Multituberculata, Sacculusorexida, Sacculusorexidae
The Mesozoic era was a sort of golden age for various animal groups, where these reached their greatest dominance and peak of diversity in their evolutionary history, most notably, of course, the dinosaurs (on land) and other reptile groups such as the pterosaurs (flying guilds) and various marine reptiles (in the sea) as well as more familiar fauna such as the pseudosuchians (crocodilians, here including both modern and archaic groups), but also, more suprisingly… mammals.
Indeed, mammals actually had their greastest diversity not in the Cenozoic but actually in the Mesozoic, in which they were represented by a much greater number of clades than the three sole surviving ones in our timeline's today, the placentals, marsupials and monotremes.
Many more groups, each with representatives filling a great and diverse array of niches, shapes, ecologies and lifestyles, coexisted alongside the modern ones.
Even if remaining small, due to competition and predation from dinosaurs, mammals still thrived in their own right, with them, back then, filling the guilds of the myriads of small mammals existing in our timeline's today. They ranged from small insectivores to omnivores, carnivores, piscivores, terrestrial, arboreal, aquatic and even gliding forms, from shrew or rodent-sized to (much larger) badger to coyote-sized animals (the latter approaching the maximum they could achieve with dinosaurs present), and so on, regarding other traits.
The Cretaceous was especially the period where, alongside and in parallel with the dinosaurs, mammals reached their highest and most successfull point.
Even if mammals had their incredible later radiation thanks to the K-Pg extinction event, which occured approximatively 66 mya ago, ending both the Cretaceous and the Mesozoic as a whole, and starting the Cenozoic period, with these increasing massively in sizes and taking the dominant megafaunal niches of their reptilian predecessors… it has to be noted the extinction itself actually not only wiped out the majority of dinosaurs, but also a sheer majority of mammals themselves. Similarly hit hard by the catastrophic event, one where came near to extinction, with less than our timeline's extant clades present today dissappearing entirely.
Among the groups of mammals that existed at the last hours of the Cretaceous, and actually survived the event, but only are known to have existed for a while into the so-called "Age of Mammals" before fading from the fossil record entirely, were the multituberculates. A decently well-known group of small mammals, which are more notable for being very convergent to rodents, visually, being among the primary mammal clades to dominate most of the Mesozoic. They fit the guilds of our timeline's modern analogs, and enjoyed similar lifestyles as these. They were small organisms with incisor teeth, which were used to process various organic materials, including tough ones, making them very flexible, adaptable animals, and at the base of the food chain. They served, as a result, as important food sources for various animals higher in trophic levels.
Mammals, as a whole throughout much of their Mesozoic existence, thrived and lived on all continents, in all types of climates and habitats, and multituberculates weren’t an exception to the rule, with one very particular, mysterious and unique representative being also one of the representatives of the group which existed right before the occurence of the final Cretaceous extinction event.
Found in what would have been among the northernmost areas of North America, especially in Canada, is the genus and species Sacculusorex arctous, a mutituberculate of very odd features.
Known primarily for its teeth and parts of the skull, this creature was found in areas of very low preservation. It inhabited cold, dry and temperate forests, predominantly dominated by conifers, which often grow in acidic soils, and so don’t allow many chances of fossilization, especially for small animals.
Because it could be mistaken as a very archaic and ancient type of shrew (Soricidae), which, ocasionally, these and related groups such as, and especially, solenodonts, but also the various unrelated clades that were formerly members of the now defunct Insectivora order, were thought to represent the way mammals as a whole were physically and ecologically back during the "Age of the Dinosaurs", it was named as such.
The fact that it preserves a lower body where its possible to determine there's the presence of epipubic bones, a pelvic bone which in most marsupials straightens their occasionally pouched torso, it reveals that this creature could have a similar torso arrangement and could have had a pouch when alive. A pouch couls be another feature which assumed to be strongly associated with primitivity in mammals, as marsupials were, until recently, considered a transition regarding their reproduction between the egg-laying monotremes and the more developed live-birthed offsprings in placentals.
Now, both ideas of mammals being entirely shrew-like during the Mesozoic and marsupials being inherently more primitive than placentals and in-between these and monotremes are known to be very outdated ideas.
Sacculusorex is a sure member of the multituberculates. However, still surprisingly enough, in a stunning twist, its not a part of the two already established major clades known to compose that group, being part of neither the Plagiaulacida (which is paraphyletic) or Cimolodonta.
Instead, they're found to be a part of a third, novel clade of multituberculates, the Sacculusorexida, to which it is the only genus and species known so far.
This group is thought to represent a more basal, ancient lineage which diverged early in the evolution of the greater clade, having split from its two other branches shortly after multituberculates have evolved and appeared, during the Middle Jurassic. From then, it escaped the fossil record and became, as an effect, an important ghost lineage.
The multituberculates part of this lineage, likely early after their first appearance, developed a very convergent reproduction with marsupials. Developing pouchs and giving birth to under developed offsprings, then raised in said pouches until fully becoming independent, they grew and reproduced fast and capable to giving birth frequently. This allowed them to renew their population quickly and endure predation from predators. This was a quite succesfull strategy in the R-selected imposed context of the dinosaur-dominated ecosystems.
Aside from that, the rest of the anatomy of Sacculusorex itself, mostly its teeth, seems to be rather derived, with these having converged into a less rodent-like disposition and shape. The tubercules on their teeth (hence the name of the whole group) are sharper, conical and fang-like, with the main lower teeth most notable in these animals for being longer/elongated, occupying a greater place on the lower jaw (along the length of it), closer to the lower inscisors set, with 3 pointed spiked tubercules.
The dentition as a whole, including the upper teeth and remaining lower teeth behind the main large one, and especially when fragmentary, look more similar, visually, to the one of a shrew, hence a possible misidentification.
In life, Sacculusorex would have been a small, mostly crepuscular to nocturnal mammal, living on and under the ground, fitting the guild of modern shrews, being a generalist omnivore with predominantly predatory tendencies, going predominantly for animal material of any kind. It possessed a dense, potentially woolly coat of fur to allow it to survive the often intense cold of its habitat and long nights of its polar region, which frequently had a duration of several months. It would have sheltered in burrows, and likely could also enter torpor, even fully hibernating to survive and pass the winter.
It is not known if this mammal succeeds at surviving the end Cretaceous extinction event, as organisms that lived in polar areas are speculated to have endured better and longer through the incident than the ones closer to the equator, with a good chunk of Cenozoic survivors hypothesized to be from these polar areas, but in any case, the multituberculate clade Sacculusorexida is so far nowhere to be seen in the fossil record pass this point. A null Cenozoic fossil presence is observed, unlike one of its other, related multituberculate clades, the Cimolodonta, which survived well into the Paleocene and beyond.
Clades (multiple related species submissions; 2 - 3 species)
Clades (multiple related species submissions; 2 - 3 species)
Name: Epipepterydontini
Creator: TheTiger773
Location: Northwestern Eurasia and northeastern North America
Clade: Animalia, Eumetazoa, ParaHoxozoa, Planulozoa, Bilateria, Nephrozoa, Deuterostomia, Chordata, Olfactores, Vertebrata, Placodermi, Eugnathostomata, Osteichthyes, Sarcopterygii, Rhipidistia, Tetrapodomorpha, Choanata, Eotetrapodiformes, Elpistostegalia, Stegocephali, Tetrapoda, Reptiliomorpha, Romeriida, Amniota, Reptilia, Sauropsida, Neoreptilia, Parapleurota, Neodiapsida, Sauria, Archelosauria, Archosauromorpha, Parathecodontia, Crocopoda, Archosauriformes, Eucrocopoda, Archosauria, Avemetatarsalia, Ornithodira, Pterosauromorpha, Pterosauria, Lonchognatha, Zambellisauria, Macronychoptera, Novialoidea, Breviquartossa, Pterodactylomorpha, Caelidracones, Anurognathidae, Anurognathinae
Epipepterydontini is a small tribe within the greater Anurognathidae family, which ecompasses two genera - Vespertisciurus with three species and Pteroagelatus with one. What differentiates them from most other anurognathids, but also from most other pterosaurs, is their diet. Namely, members of Epipepterydontini feed readily on plant matter, which is a trait shared by the unrelated tapejarids. However, the amount of said plant matter that is consumed differs from species to species. This stands in contrast to the other, earlier anurognathids, which are belived to be mostly insectivorous. This change towards a more generalistic diet allowed them to survive up to this point in time. Because of that, teeth of Epipepterydontini are shorter and blunter in order to better process the plant matter in comparison to their ancestors. This anatomical difference is also the reason behind the name of this tribe. Despite this adaptation, Epipepterydontini and the rest of Anurognathidae went extinct soon after.
Name: Pteroagelatus argus
Size: 55 centimeters long
Location: Northwestern Eurasia and northeastern North America
Time period: 120 mya
Pteroagelatus argus is a singular member of its genus. This species' main characteristic is its size. In fact, they are the biggest of not only the Epipepterydontini, but also the Anurognathidae. Accidentally, they're also the most herbivorous species within its tribe. P. argus diet consists mostly of leaves, supplemented by fruit-like bodies and animal matter in the form of insects. Outwardly, they are similar to the slow herbivorous sloths or koalas of our timeline's Holocene, hence the name. However, in many ways they are more similar to hoatzins. P. argus is capable of flying for short distances. Due to their size, they live in woven nests in the treetops, far from terrestrial predators.
Name: Vespertisciurus immodicus
Size: 14 centimeters long
Location: Northeastern North America
Time period: 120 mya
Vespertisciurus immodicus is one of the species from the Vespertisciurus genus. Aside of its slightly larger size and much more restricted range, relegated mostly to northeastern North America, the main difference between itself and V. parvus is its striking appearance. V. immodicus has long, brightly colored supercilia. These structures are used for intraspecific communication. Additionally, a large part of their diet consists of fruit-like bodies of gymnosperms, particularly ginkgos, making them important seed dispersers in its environment.
Name: Vespertisciurus parvus
Size: 10 centimeters long
Location: Northwestern Eurasia and northeastern North America
Time period: 120 mya
Vespertisciurus parvus is the smallest species of the Epipepterydontini and simultaneously the most widespread. Their range includes parts of northwestern Eurasia and North America. In many ways, this species is the main representative of its clade. V. parvus is an omnivorous pterosaur, feeding on insects, young leaves, mushrooms and fruit-like structures. They live in cavities of trees, both created trough natural growth and decay and carved by other animals.
Ecosystems (2-6 species that live in one shared real or fictional ecosystem)
Ecosystems (2-6 species that live in one shared real or fictional ecosystem)
Name: Corfield Formation
Creator: MrBlueShark
Time period: 72.2 - 66 mya
Location: Queensland, Australia
This geological formation is located in Queensland, Australia, close to the our timeline's town of Corfield, which the formation is named after. It has an unconformity by overlying the Winton Formation by up to 26 million years, filling a small but important gap in the fossil record of Queensland, Australia, giving us a better understanding of late Maastrichtian terrestrial fauna close to the K-Pg boundary.
The formation holds many lush and aquatic plants indicating a flooded forest ecosystem with many stagnant lakes and slow moving rivers. These conditions allowed many types of dinosaurs to fossilize, giving a good idea of the biodiversity of the area. Undescribed archosaurs include titanosaurs, elasmarians, avialans and crocodilians, which are common alongside specific genera of unenlagiines, enantiornitheans, parankylosaurs and abelisaurs that also exist in the formation.
Name: Nycticoroides austras
Size: 3 meters long
Clade: Unenlagiidae, Unenlagiinae
This definitive member of Unenlagiinae is proof of the group living in Maastrichtian Australia, being quite large and likely an important mesopredator of its ecosystem. It is known from a fairly complete skull, neck vertebrae and claws mostly resembling the paravians from South America that lived during that time. It's named after supposedly resembling a night heron after a person named Jackson Crowley.
Name: Artemisornis allops
Size: Over 1 meter tall
Clade: Ornithothoraces, Enantiornithes
One of the most surprising finds in the Corfield Formation was this giant member of the "opposite bird” group. They appear to have been flightless, judging by the surprisingly complete skeleton showing small reduced wings that were likely still utilized for balance when running or attacking prey with their large talons and jaws. The lack of dromaeosaurs in Australia seems to have made this unique predator possible for an otherwise flighted group.
Name: Rugosaurus gigas
Size: 9 meters long
Clade: Abelisauria, Abelisauridae
Large abelisaurs appear to have been common in Gondwana during the Maastrichtian, with Rugosaurus possibly being one of the largest, with even conservative estimates putting it at roughly 9 meters long. Its incomplete skeleton laid close to the remains of the parankylosaur Securisaurus. It was likely the apex predator of its time and might have competed with megaraptorans much like in South America. Its prey would have been the large parankylosaurs, elasmarians and titanosaurs that seemed to be thriving in Australia right before the Chicxulub impact, 66 million years ago.
Name: Securisaurus queenslandi
Size: 5 meters long
Clade: Ankylosauria, Parankylosauria
Parankylosaurs are typically quite small when compared to other thyreophorans of the latest Cretaceous, but Securisaurus queenslandi was an exceptionally large member of the group. It appeared to have reduced osteoderms, but very well developed ones on its neck and tail. The axe-like osteoderms on the end of their long tail would have made a lethal weapon for the contemporary abelisaurs. The head reconstruction is less well known as the skull and limbs are unrecovered in fossils.
SUGGESTED EXTINCTIONS
(clades that are suggested to go extinct in this time period)
SUGGESTED EXTINCTIONS
(clades that are suggested to go extinct in this time period)
Anurognathidae (†119.7 mya): - This family of pterosaurs was believed to go extinct during the late Barremian. However, this family survived a few more million years in North America. (TheTiger773)
SUGGESTED ECOSYSTEMS
(real or fictional ecosystems suggested by the community for other people to build into)
SUGGESTED ECOSYSTEMS
(real or fictional ecosystems suggested by the community for other people to build into)
Corfield Formation / Queensland, Australia (72.2 - 66 mya) - This geological formation is located in Queensland, Australia, close to the our timeline's town of Corfield, which the formation is named after. It has an unconformity by overlying the Winton Formation by up to 26 million years, filling a small but important gap in the fossil record of Queensland, Australia, giving us a better understanding of late Maastrichtian terrestrial fauna close to the K-Pg boundary. The formation holds many lush and aquatic plants indicating a flooded forest ecosystem with many stagnant lakes and slow moving rivers. These conditions allowed many types of dinosaurs to fossilize, giving a good idea of the biodiversity of the area. Undescribed archosaurs include titanosaurs, elasmarians, avialans and crocodilians, which are common alongside specific genera of unenlagiines, enantiornitheans, parankylosaurs and abelisaurs that also exist in the formation. (MrBlueShark)
CANON
CANON
OFFICIAL
(ultimate canonical compilation of submissions; official submissions, extinctions and ecosystems can only fall in this category after the deadline is over and proper judging can occur; I will have authority to canonize my own submissions before the deadline, however, and that information can be used by other people to build over the canon in anticipation)
OFFICIAL
(ultimate canonical compilation of submissions; official submissions, extinctions and ecosystems can only fall in this category after the deadline is over and proper judging can occur; I will have authority to canonize my own submissions before the deadline, however, and that information can be used by other people to build over the canon in anticipation)
SPECIES
Name: Alaskalien mysterio
Creator: YellowPanda2001
Size: 2 centimeters long
Location: Northern Alaska, USA
Time period: 92 mya
Clade: Alienopteridae, Arctalieninae
During the early Turonian stage, 92 million years ago, the Earth was a very warm place. Places that nowadays are frigid, like the northern expanses of Alaska, were then lush and vegetated environments, where a variety of life existed all year round. The Cretaceous is much more famous for its array of reptilian giants, but it was also the cradle for a gigantic diversification of insects, which were responding to the dramatic changes in climate and flora throughout the period. In the lush arctic forests, there is a small seldomly seen predator: Alaskalien mysterio.
This hunter is rather harmless for anything the size of a human, for it measures no more than 2 centimeters long. It is an alienopterid, a family of peculiar insects with sclerotized wings as adults and a predatory appetite, being somewhat related to mantis. Alaskalien is a master mimic that belongs to an unknown peculiar subfamily of ancient north american alienopterids known as Arctalieninae. Adults of this insect have a very elongated appearance, with enormous legs and brown and grey texture that allows them to camouflage in branches, twigs and leaves, perfectly suited to hunt for prey. It is interestingly found close to ant colonies, where it will lay its eggs. The eggs of Alaskalien will be raised unknowingly by the ants, and the flightless nymphs will hatch, looking eerily ant-like. By mimicking the ants, they can avoid being hunted down by other predators, and may even steal the pheromones of the ants to avoid being taken down by them. The nymphs will feed on bennetittalean spores and pollen before transitioning to the carnivorous lifestyle of the adults.
CLADES
ECOSYSTEMS
EXTINCTIONS
Skaracarida (†67 mya): - Perhaps most unexpected to find in the Cretaceous waters would be a ghost lineage dating back to the Cambrian period. But that is the case of the skaracarids, whose only undisputed fossil representative is Skara from the late Cambrian. These enigmatic crustaceans were probably oligostracans, a group of traditionally very tiny and planktonic invertebrates. The minute nature of skaracarids, coupled with a limited understanding of their full ontogenetic appearance, made their preservation as fossils after the Cambrian incredibly hard to recognize. Nearly 420 million years after the Cambrian, the last representatives of this group goes extinct, in the late Maastrichtian, 67 million years ago, nearly missing the end Cretaceous extinction that would occur a million years after. (YellowPanda2001)
Page updated
Google Sites
Report abuse