Extremely bizarre new herbivorous theropod published in Nature!
The platypus is a semiaquatic mammal endemic to Australia and its relatives were also present in the Patagonian region of Argentinia approximately 60 million years ago. The platypus is a duck-billed, beaver-tailed, otter-footed and egg-laying mammal that disconcerted naturalists after its discovery in the very late 18th century, and was even considered as a possible hoax. The bizarre combination of features present in the platypus that are reminiscent of those of other animals can be explained by an evolutionary process called convergence evolution. In this process, two unrelated species or groups acquire similar characteristics because they live in similar environments or share a similar behaviour. But, if the news are about a new bizarre dinosaur, why I am talking about the platypus?
diegosarezi is a new dinosaur that we named in a
scientific paper published on Monday 27th April in Nature, and its appearance
does not resemble that of a platypus at all. However, Chilesaurus does possess a bizarre combination of features, in
which, like in the platypus, different anatomical regions resemble those of
other unrelated groups of animals. Therefore, Chilesaurus can be considered a “platypus-dinosaur” because it
represents a very good example of convergent evolution and shows how evolution
works in deep time.
Life reconstructions of Chilesaurus diegosuarezi by Gabriel Lio.
Chilesaurus was found in 145 million-year-old Upper Jurassic rocks from southern Chile and published by a team of Argentinian-Chilean palaeontologists and geologists led by Dr. Fernando Novas. I am one of the co-authors on the paper. This new dinosaur is known from four fairly complete, articulated skeletons and dozens of bones from other individuals. These specimens were excavated in the south of the Andes Mountains and sometimes in rather extreme conditions, with very cold, snowy days. The place is inaccessible by car and my colleagues, who participated in the fieldworks, had to use horses to reach the locality and transport the plaster jackets.
Fieldwork in the Toqui Formation (Andes mountain range, southern Chile). Excavation of one of the most complete specimens (left) and Diego Suarez, and his father Manuel Suarez, when he discovered the first bones of the formation back in 2004 (right) (courtesy of Fernando Novas).
There is a very nice video showing the excavation and study of Chilesaurus here (courtesy of Mariano Novas and Alexis Sosa).
The bones belong to young to adult individuals, and if we consider all the specimens together, only some skull bones and the end of the tail are currently unknown. Chilesaurus was a relatively small dinosaur, with an adult total length of 3.2 metres. We infer that Chilesaurus was a plant-eater because of the presence of leaf-shaped teeth, a retroverted pubis (one of the three pelvic bones) that probably increased gut capacity for processing plant material, and the robust morphology of the hindlimb that resembles that of other herbivorous dinosaur groups (such as therizinosaurs). Chilesaurus was the most common species of the braided river system in which it lived alongside with primitive crocodiles and large long-necked dinosaurs.
Skeletal reconstruction of Chilesaurus diegosuarezi (top) and anterior half of a right dentary in lateral view (bottom) (courtesy of Gabriel Lio and Fernando Novas).
belongs to a completely unknown lineage of dinosaurs that acquired herbivore
habits from carnivorous ancestors and was probably endemic to South America. Chilesaurus is the first herbivorous
theropod (a lineage that includes predominantly predatory forms) from the
Southern Hemisphere. Nevertheless, the most outstanding about Chilesaurus are the similarities that
different regions of its body possess with those of different unrelated
dinosaur groups. The skull and neck resemble those of primitive long-necked
dinosaurs (e.g. Plateosaurus), the
vertebrae resemble those of primitive meat-eating theropods (e.g. Dilophosaurus), the pelvis is very
similar to that of ornithischian dinosaurs (e.g. Iguanodon), and the hand has only two well-developed fingers as in Tyranosaurus rex, but with an unreduced
arm. As a result, Chilesaurus looks
like a combination of different dinosaurs that completely astonished us at the
time that different regions of its anatomy were cleaned out from the
surrounding rock and later puzzled us during its study.
Results of one of the phylogenetic and morphospace analyses published in the paper. These analyses were one of my main contributions to the research.
There is no possibility that Chilesaurus is chimera made up of different dinosaur bones because we found four fairly articulated skeletons. The strange body of Chilesaurus shows that the evolutionary pressures that acted on its ancestor species lead to the selection of similar structures to those of other dinosaur groups with similar pressures driven by their environment or mode of life. In the case of Chilesaurus, this convergent evolution acted in mosaic in different parts of its body, such as also occurred in the platypus lineage. The presence of these multiple features shared by Chilesaurus and unrelated dinosaur groups was very challenging as we attempted to determine the relationships of the new species in the dinosaur “genealogical tree”. We proposed that the new dinosaur is a primitive tetanuran, a group of theropods that includes Megalosaurus, Allosaurus, Tyrannosaurus and birds, but not Carnotaurus and early dinosaurs. However, the bizarre anatomy of Chilesaurus will probably open a heated discussion about its relationships, with possible implications for the relationships of the main dinosaur groups. Chilesaurus reveals how much data is still completely unknown about dinosaurs and waits to be discovered in the rocks that tell the story of our planet in deep time.
After three years of incredibly hard work, Martín recently submitted his PhD. It is an extraordinary volume of work - 570 pages including appendices, but could have been much longer - and I am delighted to see my first PhD student submit. Mixed emotions for me - I'm extremely proud, but I'm also very sad because it means that soon Martín will be returning to Argentina. But first, there is the small matter of the defence, and we're looking forward to welcoming Professor Mike Benton as external examiner. Most of the chapters of Martín's thesis are already published, but he's currently working hard on preparing the final chapter for publication as well.
Just over a week ago, it was my pleasure to have been invited to the Burpee Museum of Natural History in Rockford, Illinois, to give a talk at the annual PaleoFest meeting, organised in association with the Smithsonian's National Museum of Natural History. Together with 23 other experts on the early Mesozoic, I spoke in a symposium on the The Beginning of Dinosaurs and The Origins of the Modern World, presenting an overview of our research on the Triassic rise of archosauromorphs. It was an enormously enjoyable meeting, and I am grateful to Hans-Dieter Sues and Scott Williams for the invitation. A personal highlight was receiving a gift of a beautiful geological hammer engraved with my name from the legendary manufacturers Estwing, who are based in Rockford.
Back before Christmas I was utterly delighted to discover that I have been awarded a European Research Council Starting Grant worth close to €1.5 million. This was awarded for a five-year research project that will focus on the patterns and drivers of tetrapod diversification on land from the Devonian to the present day, and which is entitled "TERRA. 375 Million Years of the Diversification of Life on Land: Shifting the Paradigm?" Using this funding, I intend to build a research group including PhD students, postdocs and research assistants that will use tetrapods as an exemplar group to revise our understanding of the long-term shape of life's diversification in the terrestrial realm. I'm looking forward to getting started with this project, once all the admin is complete and I've (more-or-less) cleared the deck of other projects!
Yet again I'm playing catch-up on the news front, so I'm going to rush out a few posts on some of the things we've been doing the last few months. One of the most exciting was the opportunity in January to do fieldwork and visit fossil collections in India. This was funded by a National Geographic Young Explorer's Award to Martín (fieldwork), as well as our Marie Curie CIG funding (collections work). Martín, Roland and I flew to Kolkata in West Bengal, where we joined our colleagues Dr Saswati Bandyopadhyay and Dr Dhurjati Sengupta of the Geological Studies Unit of the Indian Statistical Institute. Our target was the Lower Triassic Panchet Formation of West Bengal, from which an important but generally fragmentary assemblage of vertebrate material has previously been collected from immediately after the Permo-Triassic extinction event. Our aims were to collect additional material, particularly of proterosuchid archosauromorphs, and better understand the recovery from the extinction in this part of Pangaea.
Outcrops were generally sparse, but we did find a significant number of specimens in the bed of the Damodar River. These included remains of temnospondyl amphibians, fish, and the dicynodont Lystrosaurus, but also, more excitingly (for us), a number of specimens belonging to proterosuchids. These were all isolated cranial and postcranial elements, but together with historically collected material that we examined back in Kolkata, they are going to help us build up a more complete picture of the Panchet fauna. Martín will be back in Kolkata in May to work on some of the specimens, and we're planning a couple of papers revising the fauna.
Temnospondyl jaw in situ in the Panchet Formation. My best find!
The field crew, including Dr Saswati Bandyopadhyay (third from left) and Dr Dhurjati Sengupta (second from right)
Birmingham recently hosted the British Science Festival, with many fantastic public events and talks here on the UoB campus and across the city. It was an exhausting week, but very rewarding! I organised an event on "Virtual Palaeontology", co-sponsored by the Palaeontological Association and the Lapworth Museum of Geology, with Imran Rahman and Russell Garwood giving great talks on how they use CT scanning in their research on Palaeozoic fossils. On the Sunday of the festival, we welcomed around two thousand people, mostly families with young children, into the Lapworth Museum, for a range of exciting activities relating to fossils and rocks. On the same day, I had the honour of giving the Halstead Lecture, sponsored by the Geological Association and the British Science Association. I spoke to a packed room on the origin and evolutionary rise of dinosaurs.
My talk picked up a bit of media interest, with an article appearing in the Sunday Times, and two articles in Forbes.
I'm a bit delayed posting this, but together with a team of researchers from the UK, Switzerland, and the USA, I was recently involved in the description of the first dinosaur from Venezuela, which we named Laquintasaura venezuelae in a paper in Proceedings of the Royal Society B. Laquintasaura is exciting for a number of reasons: it is the first dinosaur from northern South America, a rare example of a dinosaur from the palaeoequatorial region, and perhaps the earliest evidence for social behaviour in ornithischian dinosaurs. However, the most exciting thing is that our new radioisotopic data reveals that Laquintasaura came from rocks that might be less than a million years younger than the Triassic-Jurassic mass extinction, and so provides a rare window into how dinosaurs fared in the immediate aftermath of that event. It seems that ornithischian dinosaurs, at least, were doing pretty well!
Life reconstruction of Laquintasaura by Dr Mark Witton.
I did an interview for BBC West Midlands on this new discovery, which you can watch below.
Barrett, P. M., BUTLER, R. J., Mundil, R., Scheyer, T. M., Irmis, R. B. & Sánchez-Villagra, M. R. 2014. A palaeoequatorial ornithischian and new constraints on early dinosaur diversification. Proceedings of the Royal Society B 281: 20141147.
I am joint lead author with my friend and colleague Steve Brusatte on a new review paper on the dinosaur extinction, published yesterday in the journal Biological Reviews. The paper is currently free to download. To write this paper we brought together an international team of 11 dinosaur and Cretaceous-Palaeogene boundary researchers, to attempt to reach a consensus on the causes and dynamics of the dinosaur extinction. Our primary conclusion is that the asteroid impact was indeed the main killing mechanism, but that dinosaur ecosystems may have been particularly vulnerable to the effects of this impact due to losses in biodiversity among some large herbivorous groups. These biodiversity declines may have been the result of other environmental changes occurring during the Late Cretaceous, such as sea level falls and massive Deccan volcanism.As you might expect, we received a fair degree of media coverage. I did a live TV interview with BBC World/BBC4, radio interviews with the Today programme (BBC Radio 4), BBC Wales, and Radio Forth, and spoke to journalists from the UK, USA, Canada, Spain and Chile. Steve did lots of media, including CBS Evening News, and other members of the research team including Paul Barrett and Phil Mannion also did live TV and radio interviews. I've posted a selection of links to news stories below:
Back in 2009, Octavio Mateus, Steve Brusatte and I took a short trip down to the Algarve in southern Portugal to search for Triassic vertebrate fossils. We were attempting to relocate a bonebed that had been discovered by a German geology student in the early 1980s, and from which he had collected some rather scrappy remains of large amphibians (temnospondyls). We managed to find the site, which actually turned out to be an extremely rich horizon, with multiple complete skulls of a new species of the temnospondyl genus Metoposaurus.
With support from several funding agencies, including the German Research Foundation (DFG) and the Jurassic Foundation, we excavated parts of the bonebed in 2010 and 2011, together with a large team including Sébastien Steyer and Jessica Whiteside. In addition to the amphibian material, an exciting discovery from a slightly higher stratigraphic level at the same site was a lower jaw of a phytosaur. Phytosaurs are a group of Late Triassic reptiles that were very crocodile-like in morphology (and probably ecology), and which are well known from central Europe (Germany, Poland, Italy) and from other continents (particularly North America). However, this group had never previously been discovered on the Iberian Peninsula. The association of a phytosaur and the temnospondyl genus Metoposaurus is very similar to early Late Triassic sites in Poland and Germany, and suggests strong faunal similarities across Europe at that time.
Above: Right lower jaw of the Portuguese phytosaur in lateral view. The anterior end of the mandible is missing.
Our new paper on this phytosaur jaw is the first fully published result of our fieldwork. Another paper on the temnospondyl fossils is currently in press, also at Journal of Vertebrate Paleontology. Fieldwork itself is currently on hold, but we hope to get this project up and running again in the near future.
Mateus, O., BUTLER, R. J., Brusatte, S. L., Steyer, J. S. & Whiteside, J. H. 2014. The first phytosaur (Diapsida, Archosauriformes) from the Late Triassic of the Iberian Peninsula. Journal of Vertebrate Paleontology 34:970-975.
Martín has won the University of Birmingham Graduate School's Michael K O'Rourke Prize for best PhD publication. Martin was selected as the overall winner for the College of Life and Environmental Sciences and the joint overall winner for the University as a whole.
Above: Martin receiving his award from Professor Gavin Schaffer, Director of Graduate Studies.
The award was in recognition of his recent paper in the journal PLOS ONE entitled "The origin and early evolution of Sauria: reassessing the Permian saurian fossil record and the timing of the crocodile-lizard divergence". The award caps an outstanding year for Martín since transferring into the Birmingham PhD programme in September 2013, which has seen his total number of peer-reviewed publications rise to 38, and the award of a prestigious Young Explorer Grant from National Geographic.
It has been a busy few months in terms of papers. As always, a full list of papers is available here. I don't have time to mention everything that we have published, but a few highlights include:
In January, Martin published a new paper in PLOS ONE on the possible proterosuchid reptile Tasmaniosaurus from the Lower Triassic of Australia. This paper resulted from Martin's visit to Hobart in Australia in 2012, and includes a comprehensive reassessment of the anatomy of this enigmatic taxon.
Left: Skull reconstruction of the Early Triassic archosauromorph Tasmaniosaurus, modified from Ezcurra (2014).
In February, Martin and I published in PLOS ONE together with Torsten Scheyer of the University of Zurich a comprehensive reassessment of the Permian fossil record of Sauria, one of the most important groups of vertebrates (which includes within it lizards, snakes, birds, crocodiles, and dinosaurs). This included a major new phylogenetic analysis of the evolutionary interrelationships of saurians and their fossil relatives, and has implications for understanding the early evolutionary history of saurians, the impact of the Permo-Triassic mass extinction, and the timing of the bird-lizard split. We named a new genus and species of Permian archosauromorph, Aenigmastropheus parringtoni, based on material collected from Tanzania. This paper results from two year’s worth of intensive research by Martin involving data collection in museums on six continents, including in Russia, China, Argentina, South Africa, Australia and the USA, and forms a key part of his PhD thesis.
Right: Dorsal vertebra of the new archosauromorph Aenigmastropheus, from the late Permian of Tanzania.
In March, I was a coauthor on a paper published in Nature Communications and led by Roger Benson of the University of Oxford that examined body size evolution in the Mesozoic flying reptiles, the pterosaurs. In this paper we examined pterosaur body size evolution over 150 million years of the Mesozoic. We demonstrated that early pterosaur body size evolution was relatively constrained, but that from the Late Jurassic onwards pterosaurs underwent strong evolutionary pressures towards the evolution of larger body sizes. This evolutionary trend culminated in giant pterosaurs with wing spans of 10 metres or more. We proposed that our results provide support for controversial hypotheses that pterosaurs were competitively replaced by the adaptive radiation of Mesozoic birds.
Left. Pterosaur wingspan plotted against time, and across pterosaur phylogeny.
Finally, just this month we published a paper in BMC Evolutionary Biology, together with Liu Jun and Corwin Sullivan of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, on the phylogeny of early archosaurs. This paper grew out of our visit to Beijing in 2013, when we examined two species of enigmatic early archosaur from the Middle Triassic of China: Turfanosuchus dabanensis and Yonghesuchus sangbiensis. In this paper we propose that these two species form a previously unrecognised clade of early archosaurs, Gracilisuchidae, together with Gracilisuchus stipanicicorum from the Middle Triassic of Argentina, and we examine the biogeographical and evolutionary implications.
Left: holotype skull of the Middle Triassic archosaur Turfanosuchus dabanensis from China in left lateral and dorsal views.
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