Benggwigwishingasuchus eremicarminis on the shore of the Panthalassan Ocean. Credit: Jorge Gonzalez
A newly discovered one Triassic crocodile relative shows that pseudosuchian archosaurs inhabited global coastal areas, significantly enriching our understanding of mezozoic marine ecosystems.
Researchers have discovered a new species extinct crocodilian relatives from the Triassic Favret Formation of Nevada, USA. Type, named Benggwigwishingasuchus eremicarminis, reveals that ancient crocodilian relatives known as pseudosuchian archosaurs dominated coasts across the globe during the Middle Triassic between 247.2 and 237 million years ago. This discovery, detailed in a study published July 10 in Biology Lettersreshapes our understanding of coastal ecosystems during the early Age of Dinosaurs.
“This exciting new species shows that pseudosuks were invading coastal habitats on a global basis during the Middle Triassic,” said Dr. Los Angeles County.
Discovering Pseudosuchian Diversity
Most of the fossils from the eastern Panthalas Ocean of the Triassic, which includes the Favret Formation, are those of marine creatures such as ammonites or marine reptiles such as the giant ichthyosaur. C. youngorum. Hence, the discovery of newly described terrestrial species B. eremicarminis it was quite unexpected.
“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 in the sea among ichthyosaurs and ammonites. It wasn’t until I saw the almost fully prepared specimen in person that I was convinced it was indeed a land animal.
A map of Middle Triassic oceans and archosauriforms described from eastern coastal environments (yellow dots), as well as 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 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 appear that many of these ‘independent experiments’ led to wider radiations of semi-aqueous groups,” Smith said.
sample of B. eremicarminis a) view of the skeleton; b) interpretation of the skeleton with color coding. Credit: photo by Stephanie Abramowicz; drawing by Dr Nicole Klein
Discovering ancient adaptations and different forms
During the Triassic, the archosaurs, the “ruling reptiles”, arose and split into two groups with two surviving representatives: birds, descendants of dinosaurs, and crocodilians (alligates, crocodiles and gharials), descendants of pseudosuchian archosaurs. B. eremicarminis. 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. 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 pseudosuks are suggesting that an underestimated amount of morphological and ecological diversity and experimentation was occurring early in the group’s history. While much of the public fascination with the Triassic centers on the origins of the dinosaurs, it was really the pseudosuchians that were doing interesting things in the early Mesozoic,” Smith said.
Exploring the ecology of B. eremicarminis
The new species highlights the diversity of these ancient reptiles during the Triassic, from giants like Mambawakale take care for smaller animals like those just described B. eremicarminis, which probably reached about 5–6 feet in length. Exactly how long B. eremicarminis it was and how it survived along the coasts remains shrouded in the past. 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 more clear is that B. eremicarminis likely stuck too close to shore. Its well-preserved limbs are well developed with none of the signs of aquatic life such as flipping or changes in 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 “catch fish” in Shoshone, was combined with the Greek word for Sobek, the crocodile-headed Egyptian god, to create the new genus, Benggwigwishingasuchus. Specific epithet eremicarminis translates to “desert song,” honoring two NHMLAC supporters who share a passion for paleontology and Southwest opera. Thus, the full name is meant to roughly translate as “Desert Song of the Fisherman Croc”.
Reference: “A new pseudosuchian from Nevada’s Favret Formation reveals that archosauriforms invaded coastal regions globally during the Middle Triassic” by Nathan D. Smith, Nicole Klein, P. Martin Sander, and Lars Schmitz, July 10, 2024 Biology Letters.
DOI: 10.1098/rsbl.2024.0136