Ancient predator found in Nevada rewrites the story of Triassic coastal life

a new discovery Triassic Crocodilian evidence shows that pseudosuchian archosaurs inhabited global coastal regions, significantly expanding our understanding of the ecosystem. Mesozoic Marine ecosystem.

Researchers have made a new discovery species Extinct crocodile relative from the Triassic Favorite Formation of Nevada, USA. Species, named after Bengwigwishingasuchus eremicarminisThe finding suggests that ancient crocodile relatives known as pseudosuchian archosaurs dominated coastlines across the Middle Triassic globe between 247.2 and 237 million years ago. The discovery is detailed in a study published July 10 in the Journal of the American Academy of Sciences Biology LettersThis study reshapes our understanding of coastal ecosystems during the early age of dinosaurs.

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

Uncovering pseudosuchian diversity

Most of the fossils from the eastern Panthalassan Ocean of the Triassic, including the Favorit Formation, are from marine organisms such as ammonites or marine reptiles such as the giant ichthyosaurs. C. youngorum. Therefore, the discovery of newly described terrestrial species B. eremicarminis This was quite unexpected.

“Our first reaction was: what the hell is this?” said co-author Dr. Nicole Klein of the University of Bonn. “We expected to find something like marine reptiles. We couldn’t understand how a terrestrial animal could end up so far out in the ocean among ichthyosaurs and ammonites. Only after seeing the almost complete specimen in person did I feel convinced that it was indeed a terrestrial animal.”

Map of the Middle Triassic oceans and described archosauriforms from eastern coastal regions (yellow dots), plus the new species B. eremicarminis from the Panthalassan coast (red star). Credit: Nate Smith

Evolutionary insights from fossil discoveries

Pseudosuchian archosaurs have been discovered in fossil beds from the coasts of the ancient Tethys Ocean, but this is the first coastal representative from the Panthalassan Ocean and the Western Hemisphere, showing that these crocodile relatives were present in coastal environments around the world during the Middle Triassic. Interestingly, these coastal species are not all from the same evolutionary group, suggesting that pseudosuchians (and archosauriforms more broadly) were independently adapting to life along the coasts.

“Basically, it looks like during the Middle Triassic you had a lot of different archosauriform groups that decided to dip their feet in the water. Interestingly, it doesn’t seem like many of these ‘independent experiments’ led to widespread radiations of semi-aquatic groups,” Smith said.

B. eremicarminis specimen A) Overview of the skeleton; B) Color-coded annotation of the skeleton. Credit: Photo by Stephanie Abramowicz; Illustration by Dr. Nicole Klein

Ancient adaptations and diverse forms revealed

During the Triassic, archosaurs, the “ruling reptiles”, emerged and split into two groups, with two living representatives: birds, descendants of the dinosaurs, and crocodilians (crocodiles, gharials, and alligators), descendants of pseudosuchian archosaurs such as B. eremicarminisWhile today’s crocodiles are so similar that most people mistake them for one another, their ancient relatives were very different in size and lifestyle. B. eremicarminis and its relatives show that pseudosuchians achieved great diversity very quickly after the end-Permian mass extinction – the extent of which remains to be discovered in the fossil record.

“A growing number of recent discoveries of Middle Triassic pseudosuchians are indicating that an underappreciated amount of morphological and ecological diversity and experimentation was occurring early in the group’s history. While a lot of people’s fascination with the Triassic focuses on the origin of the dinosaurs, it was actually the pseudosuchians that were doing interesting things early in the Mesozoic,” Smith said.

Exploring the ecology of the B. eremicarminis

The new species highlights the abundance of these ancient reptiles during the Triassic Period, which included giant reptiles such as Mambavakele Spirit for small animals such as the newly described B. eremicarminisWhose length was probably 5-6 feet. How long was it actually B. eremicarminis How it came to be and how it survived on the coasts is all hidden in the past. Only a few elements of the individual’s skull were found, and there are no clues about how it fed and hunted. What is even more clear is that B. eremicarminis It probably stranded very close to the shore. Its well-preserved limbs are well developed and show no signs of aquatic life such as fins or altered bone density.

The research team wanted a name that would pay respect to the original human inhabitants of the Augusta Mountains where the specimen was found, and so consulted a member of the Fallon Paiute Shoshone tribe to decide on a suitable name. “Benggwi-gwishinga”, a word that means “fishing” in Shoshone, was combined with the Greek word for the Egyptian crocodile-headed god Sobek, coining the new species, Bengwigwishingasuchus. Specific epithet Hermitage This translates to “desert song,” honoring two supporters of the NHMLAC who have a passion for Southwestern paleontology and opera. Thus, the full name roughly translates to “Desert Song of the Fisherman Crocodile.”

Reference: “A new pseudosuchian from the Favorite Formation of Nevada suggests that archeosauriforms occupied coastal regions globally during the Middle Triassic” by Nathan D. Smith, Nicole Klein, P. Martin Sander and Lars Schmitz, 10 July 2024, Biology Letters,
doi: 10.1098/rsbl.2024.0136