Kostensuchus atrox: a crocodile-relative “hypercarnivore” from prehistoric Patagonia was 11.5ft long and weighed 250kg
Kostensuchus atrox was a top predator which lived just before the extinction of the dinosaurs, and likely chomped on them
Kostensuchus atrox – Mounted skeleton (reconstructed 3D print and painted). José Brusco, CC-BY 4.0
A newly-discovered species of a large, crocodile-relative predator has been described via a remarkably well-preserved fossil from Argentina, according to a study published August 27, 2025, in the open-access journal PLOS One by Fernando Novas from Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”, Argentina, and colleagues.
The Chorrillo Formation formed around 70 million years ago, during the Maastrichtian age at the very end of the Cretaceous period. At this time, southern Patagonia was a warm, seasonally humid landscape of freshwater floodplains, home to creatures like dinosaurs, turtles, frogs, and various mammals.
The new fossil unearthed in this formation is largely intact, including a skull and jaws with visible details, as well as multiple bones from the body. This crocodile-like apex predator may have reached around 3.5 meters (11.5 feet) long and weighed around 250 kilograms (551 pounds), with a wide, powerful jaw and big teeth capable of devouring large prey — likely including medium-sized dinosaurs. The researchers named the species Kostensuchus atrox, referring to the Patagonian wind known in the Tehuelche native language as the Kosten and the Egyptian crocodile-headed god known as Souchos, with atrox meaning “fierce” or “harsh”.
Kostensuchus atrox – skull already prepared, freed from the rock. José Brusco, CC-BY 4.0
K. atrox itself is not a dinosaur, but rather a peirosaurid crocodyliform, an extinct group of reptiles related to modern crocodiles and alligators. This species is the second-largest predator known to scientists from the Maastrichtian Chorrillo Formation, and the researchers believe it was likely one of the top predators in the region. K. atrox is also the first crocodyliform fossil found in the Chorrillo Formation, and one of the most intact peirosaurid crocodyliforms ever found, giving scientists unique new insight into these prehistoricanimals and their ecosystem.
Kostensuchus atrox – life restauration, 3 meters long. Art by Gabriel Diaz Yanten. Gabriel Diaz Yanten, CC-BY 4.0
Author countries: Argentina, Portugal, Japan.
Funding: DP 9282-R-22 National Geographic Society https://www.nationalgeographic.org/society/ The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. ISC Faperj E-26/200.998/2024 Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro https://www.faperj.br/ The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. ISC CNPq 303596/2016-3 Conselho Nacional de Desenvolvimento Científico e Tecnológico https://www.gov.br/cnpq/pt-br The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Bibliographic information:
Novas FE, Pol D, Agnolín FL, Carvalho IdS, Manabe M, Tsuihiji T, et al., A new large hypercarnivorous crocodyliform from the Maastrichtian of Southern Patagonia, Argentina, PLoS One (2025) 20(8): e0328561, DOI: https://doi.org/10.1371/journal.pone.0328561
Mystery solved: Tridentinosaurus antiquus, the oldest fossil reptile from the Alps is, in part, an historical forgery
Palaeontological analysis shows renowned fossil thought to show soft tissue preservation is in fact just paint
A 280-million-year-old fossil that has baffled researchers for decades has been shown to be, in part, a forgery following new examination of the remnants.
The discovery has led the team led by Dr Valentina Rossi of University College Cork, Ireland (UCC) to urge caution in how the fossil is used in future research.
Tridentinosaurus antiquus was discovered in the Italian alps in 1931 and was thought to be an important specimen for understanding early reptile evolution.
Its body outline, appearing dark against the surrounding rock, was initially interpreted as preserved soft tissues. This led to its classification as a member of the reptile group Protorosauria.
Tridentinosaurus antiquus was discovered in the Italian alps in 1931 and was thought to be an important specimen for understanding early reptile evolution – but has now been found to be, in part a forgery. Its body outline, appearing dark against the surrounding rock, was initially interpreted as preserved soft tissues but is now known to be paint. Credits: Dr Valentina Rossi
However, this new research, published in the scientific journal Palaeontology, reveals that the fossil renowned for its remarkable preservation is mostly just black paint on a carved lizard-shaped rock surface.
The purported fossilised skin had been celebrated in articles and books but never studied in detail. The somewhat strange preservation of the fossil had left many experts uncertain about what group of reptiles this strange lizard-like animal belonged to and more generally its geological history.
Dr Rossi, of UCC’s School of Biological, Earth and Environmental Sciences, said:
“Fossil soft tissues are rare, but when found in a fossil they can reveal important biological information, for instance, the external colouration, internal anatomy and physiology.”
“The answer to all our questions was right in front of us, we had to study this fossil specimen in details to reveal its secrets – even those that perhaps we did not want to know”.
Dr Valentina Rossi with an image of Tridentinosaurus antiquus. The fossil, discovered in the Italian alps in 1931, was thought to be an important specimen for understanding early reptile evolution – but has now been found to be, in part a forgery. Its body outline, appearing dark against the surrounding rock, was initially interpreted as preserved soft tissues but is now known to be paint. Credits: Zixiao Yang
The microscopic analysis showed that the texture and composition of the material did not match that of genuine fossilised soft tissues.
Preliminary investigation using UV photography revealed that the entirety of the specimen was treated with some sort of coating material. Coating fossils with varnishes and/or lacquers was the norm in the past and sometimes is still necessary to preserve a fossil specimen in museum cabinets and exhibits. The team was hoping that beneath the coating layer, the original soft tissues were still in good condition to extract meaningful palaeobiological information.
The findings indicate that the body outline of Tridentinosaurus antiquus was artificially created, likely to enhance the appearance of the fossil. This deception misled previous researchers, and now caution is being urged when using this specimen in future studies.
The team behind this research includes contributors based in Italy at the University of Padua, Museum of Nature South Tyrol, and the Museo delle Scienze in Trento.
Co-author Prof Evelyn Kustatscher, coordinator of the project “Living with the supervolcano”, funded by the Autonomous Province of Bolzano said:
“The peculiar preservation of Tridentinosaurus had puzzled experts for decades. Now, it all makes sense. What it was described as carbonized skin, is just paint”.
However all not all is lost, and the fossil is not a complete fake. The bones of the hindlimbs, in particular, the femurs seem genuine, although poorly preserved. Moreover, the new analyses have shown the presence of tiny bony scales called osteoderms – like the scales of crocodiles – on what perhaps was the back of the animal.
This study is an example of how modern analytical palaeontology and rigorous scientific methods can resolve an almost century-old palaeontological enigma.
Bibliographic information:
Forged soft tissues revealed in the oldest fossil reptile from the early Permian of the Alps, Palaeontology (16-Feb-2024), DOI: 10.1111/pala.12690
According to a new study, published in Science, predatory dinosaurs such as Tyrannosaurus rex sported lizard-like lips
The study challenges some of the best-known depictions of predatory dinosaurs and suggests that even the giant teeth of Tyrannosaurus rex would have been covered in scaly, lizard-like lips.
A juvenile Edmontosaurus disappears into the enormous, lipped mouth of Tyrannosaurus. Credits: Mark Witton
A new study suggests that predatory dinosaurs, such as Tyrannosaurus rex, did not have permanently exposed teeth as depicted in films such as Jurassic Park, but instead had scaly, lizard-like lips covering and sealing their mouths.
Researchers and artists have debated whether theropod dinosaurs, the group of two-legged dinosaurs that includes carnivores and top predators like T. rex and Velociraptor, as well as birds, had lipless mouths where perpetually visible upper teeth hung over their lower jaws, similar to the mouth of a crocodile.
However, an international team of researchers challenge some of the best-known depictions, and say these dinosaurs had lips similar to those of lizards and their relative, the tuatara – a rare reptile found only in New Zealand, which are the last survivors of an order of reptiles that thrived in the age of the dinosaurs.
A half-grown Tyrannosaurus, sporting a full set of lips, runs down Struthiomimus, a beaked ostrich dinosaur. Credits: Mark Witton
In the most detailed study of this issue yet, the researchers examined the tooth structure, wear patterns and jaw morphology of lipped and lipless reptile groups and found that theropod mouth anatomy and functionality resembles that of lizards more than crocodiles. This implies lizard-like oral tissues, including scaly lips covering their teeth.
These lips were probably not muscular, like they are in mammals. Most reptile lips cover their teeth but cannot be moved independently – they cannot be curled back into a snarl, or make other sorts of movements we associate with lips in humans or other mammals.
Tyrannosaurus rex bellowing with its mouth shut, like a vocalising alligator. With its mouth closed, all of the enormous teeth of T. rex would be invisible behind its lips. Credits: Mark Witton
Study co-author Derek Larson, Collections Manager and Researcher in Palaeontology at the Royal BC Museum in Canada, said: “Palaeontologists often like to compare extinct animals to their closest living relatives, but in the case of dinosaurs, their closest relatives have been evolutionarily distinct for hundreds of millions of years and today are incredibly specialised.
“It’s quite remarkable how similar theropod teeth are to monitor lizards. From the smallest dwarf monitor to the Komodo dragon, the teeth function in much the same way. So, monitors can be compared quite favourably with extinct animals like theropod dinosaurs based on this similarity of function, even though they are not closely related.”
Co-author Dr Mark Witton from the University of Portsmouth said: “Dinosaur artists have gone back and forth on lips since we started restoring dinosaurs during the 19th century, but lipless dinosaurs became more prominent in the 1980s and 1990s. They were then deeply rooted in popular culture through films and documentaries — Jurassic Park and its sequels, Walking with Dinosaurs and so on.
“Curiously, there was never a dedicated study or discovery instigating this change and, to a large extent, it probably reflected preference for a new, ferocious-looking aesthetic rather than a shift in scientific thinking. We’re upending this popular depiction by covering their teeth with lizard-like lips. This means a lot of our favourite dinosaur depictions are incorrect, including the iconic Jurassic Park T. rex.”
The results, published in the journal Science, found that tooth wear in lipless animals was markedly different from that seen in carnivorous dinosaurs and that dinosaur teeth were no larger, relative to skull size, than those of modern lizards, implying they were not too big to cover with lips.
Also, the distribution of small holes around the jaws, which supply nerves and blood to the gums and tissues around the mouth, were more lizard-like in dinosaurs than crocodile-like. Furthermore, modelling mouth closure of lipless theropod jaws showed that the lower jaw either had to crush jaw-supporting bones or disarticulate the jaw joint to seal the mouth.
“As any dentist will tell you, saliva is important for maintaining the health of your teeth. Teeth that are not covered by lips risk drying out and can be subject to more damage during feeding or fighting, as we see in crocodiles, but not in dinosaurs,” said co-author Kirstin Brink, Assistant Professor of Palaeontology at the University of Manitoba.
She added: “Dinosaur teeth have very thin enamel and mammal teeth have thick enamel (with some exceptions). Crocodile enamel is a bit thicker than dinosaur enamel, but not as thick as mammalian enamel. There are some mammal groups that do have exposed enamel, but their enamel is modified to withstand exposure.”
Thomas Cullen, Assistant Professor of Paleobiology at Auburn University and study lead author, said: “Although it’s been argued in the past that the teeth of predatory dinosaurs might be too big to be covered by lips, our study shows that, in actuality, their teeth were not atypically large. Even the giant teeth of tyrannosaurs are proportionally similar in size to those of living predatory lizards when compared for skull size, rejecting the idea that their teeth were too big to cover with lips.”
T. rex skull and head reconstructions. Credits: Mark Witton
The results provide new insights into how we reconstruct the soft-tissues and appearance of dinosaurs and other extinct species. This can give crucial information on how they fed, how they maintained their dental health, and the broader patterns of their evolution and ecology.
Dr Witton said: “Some take the view that we’re clueless about the appearance of dinosaurs beyond basic features like the number of fingers and toes. But our study, and others like it, show that we have an increasingly good handle on many aspects of dinosaur appearance. Far from being clueless, we’re now at a point where we can say ‘oh, that doesn’t have lips? Or a certain type of scale or feather?’ Then that’s as realistic a depiction of that species as a tiger without stripes.”
The researchers point out that their study doesn’t say that no extinct animals had exposed teeth — some, like sabre-toothed carnivorous mammals, or marine reptiles and flying reptiles with extremely long, interlocking teeth, almost certainly did.
A one-sheet summary of the main investigations and conclusions of the study. Credits: Mark Witton
Bibliographic information:
Theropod dinosaur facial reconstruction and the importance of soft tissues in paleobiology, Science (31-Mar-2023), DOI: 10.1126/science.abo7877
Vocal Communication Originated over 400 Million Years Ago
Acoustic communication is not only widespread in land vertebrates like birds and mammals, but also in reptiles, amphibians and fishes. Many of them are usually considered mute, but in fact show broad and complex acoustic repertoires. According to researchers at the University of Zurich, the evolutionary origin of vocal communication dates back more than 400 million years.
Tuatara are found only on New Zealand islands and are considered living fossils. They also communicate acoustically. (Image: Gabriel Jorgewich Cohen)
The use of vocalizations as a resource for communication is common among several groups of vertebrates: singing birds, croacking frogs or barking dogs are some well-known examples. These vocalizations play a fundamental role in parental care, mate attraction and various other behaviors. Despite its importance, little is known about when and at what stage in the evolutionary history of vertebrates this behavior first appeared. Comparative analyses can provide insights into the evolutionary origin of acoustic communication, but they are often plagued by missing information from key groups that have not been broadly studied.
Acoustic abilities are widespread in land vertebrates
An international research team led by the University of Zurich (UZH) has therefore focused on species that have never been accessed before. Their study includes evidence for 53 species of four major clades of land vertebrates – turtles, tuataras, caecilians and lungfishes – in the form of vocal recordings and contextual behavioral information accompanying sound production.
“This, along with a broad literature-based dataset including 1800 different species covering the entire spectrum shows that vocal communication is not only widespread in land vertebrates, but also evidence acoustic abilities in several groups previously considered non-vocal,” says first author Gabriel Jorgewich-Cohen, PhD student at the Paleontological Institute and Museum of UZH.
Many turtles, for example, which were thought to be mute are in fact showing broad and complex acoustic repertoires.
Vocal Communication Originated over 400 Million Years Ago. The researchers were even able to detect acoustic communication in lungfish. (Image: Rafael C.B. Paradero)
Last common ancestor lived about 407 million years ago
To investigate the evolutionary origins of acoustic communication in vertebrates, the researchers combined relevant data on the vocalization abilities of species like lizards, snakes, salamanders, amphibians and dipnoi with phylogenetic trait reconstruction methods. Combined with data of well-known acoustic clades like mammals, birds, and frogs, the researchers were able to map vocal communication in the vertebrate tree of life.
“We were able to reconstruct acoustic communication as a shared trait among these animals, which is at least as old as their last common ancestor that lived approximately 407 million years before present,” explains Marcelo Sánchez, who led the study.
Acoustic communication did not evolve multiple times
So far, the scientific consensus favored a convergent origin of acoustic communication among vertebrates since the morphology in hearing apparatus and its sensitivity as well as the vocal tract morphology vary considerably among vertebrates. But according to the UZH researchers, the available evidence for this hypothesis lacks relevant data from key species so far considered non-vocal or neglected.
“Our results now show that acoustic communication did not evolve multiple times in diverse clades, but has a common and ancient evolutionary origin,” concludes Sánchez.
Literature:
Gabriel Jorgewich-Cohen, Simon William Townsend, Linilson Rodrigues Padovese, et al. Common evolutionary origin of acoustic communication in choanate vertebrates, Nature Communications, 25 October 2022. DOI: 10.1038/s41467-022-33741-8
Harvard researchers find rapid evolution of reptiles was triggered by nearly 60 million years of global warming and climate change
Artistic reconstruction of the reptile adaptive radiation in a terrestrial ecosystem during the warmest period in Earth’s history. Image depicts a massive, big-headed, carnivorous erythrosuchid (close relative to crocodiles and dinosaurs) and a tiny gliding reptile at about 240 million years ago. The erythrosuchid is chasing the gliding reptile and it is propelling itself using a fossilized skull of the extinct Dimetrodon (early mammalian ancestor) in a hot and dry river valley. Credits: Image created by Henry Sharpe
Studying climate change-induced mass extinctions in the deep geological past allows researchers to explore the impact of environmental crises on organismal evolution. One principal example is the Permian-Triassic climatic crises, a series of climatic shifts driven by global warming that occurred between the Middle Permian (265 million years ago) and Middle Triassic (230 million years ago). These climatic shifts caused two of the largest mass extinctions in the history of life at the end of the Permian, the first at 261myo and the other at 252myo, the latter eliminating 86% of all animal species worldwide.
The end-Permian extinctions are important not only because of their magnitude, but also because they mark the onset of a new era in the history of the planet when reptiles became the dominant group of vertebrate animals living on land. During the Permian, vertebrate faunas on land were dominated by synapsids, the ancestors of mammals. After the Permian extinctions, in the Triassic Period (252-200 million years ago), reptiles evolved at rapid rates, creating an explosion of reptile diversity. This expansion was key to the construction of modern ecosystems and many extinct ecosystems. These rapid rates of evolution and diversification were believed by most paleontologists to be due to the extinction of competitors allowing reptiles to take over new habitats and food resources that several synapsid groups had dominated before their extinction.
Evolutionary response from reptiles to global warming and fast climatic changes. Rates of evolution (adaptive anatomical changes) in reptiles start increasing early in the Permian (at about 294 million years ago), which also marks the onset of the longest period of successive fast climatic shifts in the geological record. From 261 until 235 million years ago, increased global warming from massive volcanic eruption contributed to further climate change and led to the hottest period in Earth’s history. This resulted in two mass extinctions and the demise of reptile competitors on land (mammalian ancestors). The most intensive period of global warming coincided with the fastest rates of evolution in reptiles, marking the diversification of reptile body plans and the origin of modern reptile groups. Credits: Figure by Tiago Simões
However, in a new study in Sciences Advancesresearchers in the Department of Organismic and Evolutionary Biology and the Museum of Comparative Zoology at Harvard University and collaborators reveal the rapid evolution and radiation of reptiles began much earlier, before the end of the Permian, in connection to the steadily increasing global temperatures through a long series of climatic changes that spanned almost 60 million years in the geological record.
“We found that these periods of rapid evolution of reptiles were intimately connected to increasing temperatures. Some groups changed really fast and some less fast, but nearly all reptiles were evolving much faster than they ever had before,” said lead author postdoctoral fellow Tiago R Simões.
Previous studies on the impacts of these changes have often neglected terrestrial vertebrates due to limited data availability, focusing mostly on the response from marine animals
In this study, Simões and senior author Professor Stephanie E. Pierce (both at Harvard) worked alongside collaborators Professor Michael Caldwell (University of Alberta, Canada) and Dr. Christian Kammerer (North Carolina Museum of Natural Sciences) to examine early amniotes, which represent the forerunners of all modern mammals, reptiles, birds, and their closest extinct relatives, at the initial phase of their evolution. At this point in time the first groups of reptiles and mammal ancestors were splitting from each other and evolving along their own separate evolutionary paths.
“Reptiles represent an ideal and rare terrestrial system to study this question as they have a relatively good fossil record and survived a series of climatic crises including the ones leading up to the largest extinction in the history of complex life, the Permian-Triassic mass extinction,” said Simões.
Reptiles were relatively rare during the Permian compared to mammalian ancestors. However, things took a major shift during the Triassic when reptiles underwent a massive explosion in the number of species and morphological variety. This lead to the appearance of most of the major living groups of reptiles (crocodiles, lizards, turtles) and several groups that are now entirely extinct.
The researchers created a dataset based on extensive first-hand data collection of more than 1,000 fossil specimens from 125 species of reptiles, synapsids, and their closest relatives during approximately 140 million years before and after the Permian-Triassic extinction. They then analyzed the data to detect when these species first originated and how fast they were evolving using state-of-the-art analytical techniques such as Bayesian evolutionary analysis, which is also used to understand the evolution of viruses such as SARS-COVID 19. The researchers then combined the new dataset with global temperature data spanning several million years in the geological record to provide a broad overview of the animals’ major adaptive response towards climatic shifts.
“Our results reveal that periods of fast climatic shifts and global warming are associated with exceptionally high rates of anatomical change in most groups of reptiles as they adapted to new environmental conditions,” said Pierce, “and this process started long before the Permian-Triassic extinction, since at least 270 million years ago, indicating that the diversification of reptile body plans was not triggered by the P-T extinction event as previously thought, but in fact started tens of million years before that.”
“One reptile lineage, the lepidosaurs, which gave rise to the first lizards and tuataras, veered in the opposite direction of most reptile groups and underwent a phase of very slow rates of change to their overall anatomy,” said Simões, “essentially, their body plans were constrained by natural selection, instead of going rogue and radically changing like most other reptiles at the time.” The researchers suggest this is due to pre-adaptations on their body size to better cope with high temperatures.
“The physiology of organisms is really dependent on their body size,” said Simões, “small-bodied reptiles can better exchange heat with their surrounding environment. The first lizards and tuataras were much smaller than other groups of reptiles, not that different from their modern relatives, and so they were better adapted to cope with drastic temperature changes. The much larger ancestors of crocodiles, turtles, and dinosaurs could not lose heat as easily and had to quickly change their bodies in order to adapt to the new environmental conditions.”
Simões, Pierce, and collaborators also mapped out how body size changed across geographical regions during this timeframe. They revealed that climatic pressures on body size were so high there was a maximum body size for reptiles to survive in tropical regions during the lethally hot periods of this time.
“Large-sized reptiles basically took two routes to deal with these climate shifts,” said Pierce, “they either migrated closer to temperate regions or invaded the aquatic world where they didn’t need to worry about overheating because water can absorb heat and maintain its temperature much better than air.”
“This strong association between rising temperatures in the geological past and a biological response by dramatically different groups of reptiles suggests climate change was a key factor in explaining the origin and the explosion of new reptile body plans during the latest Permian and Triassic,” said Simões.
The researchers would like to thank the Museum of Comparative Zoology (MCZ), Harvard University, vertebrate paleontology staff and the curators across 50+ natural history collections worldwide for their help with specimen access. Funding was provided by: Alexander Agassiz Postdoctoral Fellowship, MCZ; National Sciences and Engineering Research Council of Canada (NSERC) postdoctoral fellowship; Grant KA 4133/1-1 from the Deutsche Forschungsgemeinschaft; NSERC Discovery Grant #23458 and NSERC Accelerator Grant; Faculty of Science, Chairs Research Allowance, University of Alberta; Lemann Brazil Research Fund; Funds made available through Harvard University.
Successive climate crises in the deep past drove the early evolution and radiation of reptiles, Science Advances (19-Aug-2022), DOI: 10.1126/sciadv.abq1898
Press release from Harvard University, Department of Organismic and Evolutionary Biology.
New research questions hypotheses about climate-controlled ecosystem change during the origin of dinosaurs in Argentina
A group of researchers from CONICET and the University of Utah demonstrated that during the time of the first dinosaurs, variations in the diversity and abundance of the plant and vertebrate animal species cannot be related to the climatic changes recorded throughout its deposition, in contrast with previous hypotheses.
Artist’s reconstruction of the Triassic ecosystem preserved in the Ischigualasto Formation. Animals include amphibians (bottom center-left underwater), rhynchosaurian reptiles (left mid-ground on riverbank), early crocodilian relatives (far left mid-ground and center far background), early mammal relatives (center mid-ground in river and along riverbank, and far right foreground), and early dinosaurs (far left foreground, center right foreground, and far right mid-ground). Credits: Jorge Gonzalez/Natural History Museum of Utah
In the new study, published in the open access journal Frontiers in Earth Science, the team of scientists investigated multiple independent lines of evidence (sedimentology, clay mineralogy, and geochemistry) to elucidate changes paleoclimatic conditions (such as mean annual precipitation and mean annual temperature) within the Ischigualasto Formation. These fossil-rich sedimentary rocks were deposited by rivers and streams between ~231 and 226 million years ago during the Late Triassic Period in what is now northwestern Argentina (La Rioja and San Juan provinces). In the middle of the formation, the researchers observed a clear change in conditions approximately from warmer, drier conditions to more temperate humid conditions, but no concurrent major changes could be identified in the fossil record.
An overview of extensive Ischigulasto Formation outcrops in the study area, located in La Rioja Province, northwestern Argentina. Credits: Randall Irmis/Natural History Museum of Utah
“We conclude that variations in the abundance and diversity of species, as recorded by their first and last appearances in the fossil record, are better explained by preservation and sampling biases biases than by changes in climate,” said Adriana Mancuso, lead author and CONICET independent researcher at the Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales in Mendoza, Argentina.
“What we see is that how many specimens collected from each interval of the sequence, and the chemical & physical characteristics that allow greater or lesser preservation of the remains of animals and plants, were significant factors. These two factors, collection and preservation, have more influence on the increase or decrease of abundance and diversity than the climate changes recorded,” explained Mancuso.
However, although the evolution of the ecosystem does not generally show a biotic response associated with climate change, the research group did observe a relationship between climatic variations and two groups of reptiles, rhynchosaurs (herbivorous early archosauromorphs) and pseudosuchians (crocodilian-line archosaurs).
“We did find that the abundance of rhynchosaurs and extinction of a few pseudosuchian species appear to coincide with a climate shift,” said Randall Irmis, co-author from the U and the Natural History Museum of Utah.
New research questions hypotheses about climate-controlled ecosystem change during the origin of dinosaurs in Argentina: a team member exposes fresh rock to obtain a geologic sample for geochemical lab analysis to reconstruct the paleoclimate record of the Ischigualasto Formation. Credits: Adriana Mancuso
Beyond conclusions about this specific fossil and paleoclimate record from Argentina, the new research emphasizes the importance of an explicit framework for testing hypotheses about the link between climatic changes and the fossil record.
“In addition to the contribution on the relationship of biotic and climatic events in the Ischigualasto Formation, the work provides a methodological framework to test climate-biota associations, highlighting the data gaps that must be filled, and makes new testable predictions that can be tested in future studies,” concludes Mancuso.
Other authors include Tomás Pedernera and Cecilia Benavente of the Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales (CONICET), Leandro Gaetano from the Instituto de Estudios Andinos (CONICET) and Departamento de Ciencias Geológicas of the Universidad de Buenos Aires, and Benjamin Breeden of the University of Utah.
Bibliographical information:
Paleoenvironmental and biotic changes in the Late Triassic of Argentina: testing hypotheses of abiotic forcing at the basin scale, Frontiers in Earth Science (13-Jun-2022), DOI: 10.3389/feart.2022.883788
