Discovery of ancient predator in Nevada rewrites story of coastal life in the Triassic period

Newly discovered Triassic The crocodile relative shows that pseudosaurs inhabited global coastal areas, greatly enriching our understanding of Middle Ages Marine ecosystems.

Researchers have discovered something new. Class An extinct crocodile relative from the Triassic Favret Formation of Nevada, USA. The species, named Benguiguishengasuchus erimicarmenisThe discovery reveals that ancient crocodile relatives known as pseudosaurs dominated shorelines around the world during the Middle Triassic period, between 247.2 and 237 million years ago. The finding is detailed in a study published July 10 in the journal Biology messagesreshapes our understanding of coastal ecosystems during the early age of dinosaurs.

“This exciting new species shows that pseudosaurs occupied coastal habitats globally during the Middle Triassic,” said Dr. Nate Smith, lead author of the paper, and Gretchen Augustine, director and curator of the Dinosaur Institute at the Natural History Museum of Los Angeles County.

Uncovering false diversity

Most of the fossils from the eastern Triassic Panthalassan Ocean, which includes the Favret Formation, are of marine organisms such as ammonites or marine reptiles such as the giant ichthyosaur. C. Youngrum. Therefore, the discovery of newly described terrestrial species b. erimicarmenes It was completely unexpected.

“Our first reaction was: What the hell is this? We expected to find something like a marine reptile. We couldn’t understand how a land animal could end up so far out at sea between ichthyosaurs and ammonites,” said study co-author Dr Nicole Klein from the University of Bonn. “It wasn’t until I saw the almost fully prepared specimen that I was convinced it was a land animal.”

Map of the Middle Triassic oceans and described archosaurians from eastern coastal environments (yellow dots), as well as the new species B. eremicarminis from the Panthalassan Coast (red star). Copyright: Nate Smith

Evolutionary Insights from Fossil Discoveries

Parasaurian archosaurs have been discovered in fossil beds from the shores of the ancient Tethys Ocean, but this is the first coastal representative from the Panthalassian Ocean and the Western Hemisphere, revealing that these crocodile relatives were present in coastal environments worldwide during the Middle Triassic. Interestingly, these coastal species are not all from the same evolutionary group, suggesting that parasaurians (and archosaurs more broadly) were independently adapting to life along shores.

“Basically, it looks like there were a bunch of very different archosaur groups that decided to go into the water during the Middle Triassic. What’s interesting is that many of these ‘independent experiments’ don’t seem to have led to a wider spread of semi-aquatic groups,” Smith said.

B. eremicarminis specimen a) Skeletal overview; b) Skeletal interpretation in color. Copyright: Photograph by Stephanie Abramovic; illustration by Dr. Nicole Klein

Uncovering ancient adaptations and diverse forms

During the Triassic, the archosaurs, the “ruling reptiles”, arose and split into two groups with two surviving representatives: birds, descendants of dinosaurs, and crocodiles (crocodiles, gharial crocodiles), descendants of pseudo-archosaurs such as b. eremicarmenesWhile today’s crocodiles are similar enough to be mistaken for most people, their ancient relatives were very different in size and lifestyle. The evolutionary relationships between ancient and modern crocodiles were very different. b. erimicarmenes The results of the study of different species of reptiles and their relatives indicate that pseudo-reptiles achieved great diversification very quickly after the mass extinction at the end of the Permian period – the extent of which remains to be discovered in the fossil record.

“The growing number of recent discoveries of pseudosuchians from the Middle Triassic suggest that an unappreciated amount of morphological, ecological and experimental diversity was occurring early in the group’s history. While much of the public’s interest in the Triassic focuses on the origin of dinosaurs, it was actually the pseudosuchians who were doing interesting things at the beginning of the Mesozoic,” Smith said.

Explore the environment b. erimicarmenes

The new species confirms the diversity of these ancient reptiles during the Triassic period, from giants such as Mambawakali Ruhuhu to smaller animals such as those recently described b. eremicarmeneswhich probably reached about 5-6 feet in length. How long exactly was it? b. erimicarmenes It is still unknown how it lived along the coasts. Only a few elements of the individual’s skull have been found, and any evidence of how it fed and hunted is also absent. What is most clear is that b. eremicarmenes It is likely to have been stuck near the shore. Its well-preserved limbs are well developed with no signs of aquatic life such as fins or altered bone density.

The research team wanted to choose a name that would respect the indigenous people of the Augusta Mountains where the specimen was found, so they consulted a member of the Fallon Paiute Shoshoni tribe to determine an appropriate name. The word “Pingwe-goishinga,” a Shoshoni word meaning “fishing,” was combined with the Greek word for Sobek, the Egyptian god with the crocodile’s head, to form the new genus. Benguiguichingasuchos. Specific title Erymicarmenis The word translates to “Desert Song,” in honor of two NHMLAC supporters who had a passion for paleontology and opera in the Southwest. Thus, the full name is meant to roughly translate to “Desert Song of the Crocodile Hunter.”

Reference: “A New Succulent from the Favret Formation of Nevada Reveals that Archosaurs Occupied Coastal Areas Worldwide During the Middle Triassic” by Nathan D. Smith, Nicole Klein, P. Martin Sander, and Lars Schmitz, July 10, 2024, Biology messages.
DOI: 10.1098/rsbl.2024.0136