A new species of extinct crocodile relative rewrites life on the Triassic coastline

The surprising discovery of a new species of extinct crocodilian relative from the Triassic Favret Formation of Nevada, USA, rewrote the history of life along the coasts during the first act of the Age of Dinosaurs.

Described in a study published in Biology Lettersthe new species Benggwigwishingasuchus eremicarminis reveals that while giant ichthyosaurs ruled the oceans, ancient crocodilian relatives known as pseudosuchian archosaurs ruled the coasts across the globe in the Middle Triassic between 247.2 and 237 million years ago.

“This exciting new species shows that pseudosuchians were occupying coastal habitats on a global basis during the Middle Triassic,” said Dr. Los Angeles County.

Capturing fossil life from the eastern Panthalassan ocean of the Triassic, the locality comprising the Favret Formation is known for fossils of marine creatures such as ammonites along with marine reptiles such as the giant ichthyosaur C. youngorum – finding the newly described B. eremicari. like a bit of a shock.

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

Pseudosuchian archosaurs have been discovered in fossil beds from the shores of the ancient Tethys Ocean, but this is the first coastal representative from the Panthalassan Ocean and the Western Hemisphere, revealing that these crocodilian 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 pseudosuchians (and archosauriforms more broadly) were independently adapting to life along coasts.

“Basically, it looks like you had a bunch of very different archosauriform groups that decided to dip their toes in the water during the Middle Triassic. What’s interesting is that it doesn’t look like many of these ‘independent experiments’ led to broader radiations of semi-aquatic groups,” Smith said.

During the Triassic, the archosaurs, the “ruling reptiles”, arose and split into two groups with two surviving representatives: birds, descendants of dinosaurs, and crocodilians (alligators, crocodiles and gharials), descendants of the pseudosuchian archossemiscaremiseraur.

While today’s crocodiles are similar enough to be mistaken for one another by most people, their ancient relatives varied enormously in size and lifestyle. The evolutionary relationships of B. eremicarminis and its relatives suggest that pseudosuchians achieved great diversity very soon after the End-Permian mass extinction—the extent of which remains to be revealed in the fossil record.

“A growing number of recent discoveries of Middle Triassic pseudosucans are suggesting that an underestimated amount of morphological and ecological diversity and experimentation was occurring early in the group’s history. While much public fascination with the Triassic focuses on at the origin of the dinosaurs, it’s really the pseudosuchians that were doing interesting things in the early Mesozoic,” Smith said.

The new species highlights the diversity of these ancient reptiles during the Triassic, from giants like Mambawakale ruhuhu to smaller animals like the newly described B. eremicarminis, which probably reached around 5-6 meters in length. Exactly how long B. eremicarminis was around and how it survived along the coasts remains shrouded in mystery.

Only a few elements of the individual’s skull were found, and any clues about how it fed and hunted are similarly lacking. What is clearer is that B. eremicarminis is likely to stay very close to shore. Its well-preserved limbs are well developed with none of the signs of aquatic life, such as flippers or altered bone density.

The research team wanted a name that respected the original human inhabitants of the Augusta Mountains where the specimen was found, and so consulted with a member of the Fallon Paiute Shoshone tribe to decide on an appropriate name.

“Benggwi-Gwishinga,” a word meaning “fish catch” in Shoshone, was combined with the Greek word for Sobek, the crocodile-headed Egyptian god, to create the new genus, Benggwigwishingasuchus. The specific epithet eremicarminis translates to “song of the desert,” honoring two NHMLAC supporters who have a passion for Southwest paleontology and opera. Thus, the full name is meant to roughly translate as “Desert Song of the Fisherman Croc”.