Benggwigwishingasuchus eremicarminis on the shores of the Panthalassan Ocean. Credit: Jorge Gonzalez
Newly discovered Triassic crocodile relative shows that pseudosuchian archosaurs inhabited global coastal regions, significantly enriching our understanding mesozoic marine ecosystems.
Scientists have discovered a new species of an extinct crocodilian relative from the Triassic Favret Formation of Nevada, USA. Species, named Benggwigwishingasuchus eremicarminis, reveals that an ancient crocodilian genus known as pseudosuchian archosaurs dominated the coast throughout the Middle Triassic between 247.2 and 237 million years ago. This finding is detailed in a study published on 10 Biology lettersreshaping our understanding of coastal ecosystems during the early age of dinosaurs.
“This exciting new species demonstrates that pseudosuchians occupied coastal habitats on a global basis during the Middle Triassic,” said Dr. Nate Smith, lead author of the article, and Gretchen Augustyn, director and curator of the Dinosaur Institute at the Natural History Museum of Los Angeles County.
Revealing pseudosuchian diversity
Most of the fossils from the eastern Panthalassan Ocean in the Triassic, which includes the Favret Formation, are from marine creatures such as ammonites or marine reptiles such as the giant ichthyosaur. C. youngorum. Hence the discovery of a newly described terrestrial species B. eremicarminis it was quite unexpected.
“Our first reaction was, ‘What the hell?’ 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 terrestrial animal could end up so far out in the sea among ichthyosaurs and ammonites. It wasn’t until I personally saw an almost completely prepared specimen that I was convinced that it was indeed a land animal.”
Map of Middle Triassic oceans and archosauriforms described from the East Coast (yellow dots), as well as the new species B. eremicarminis from the Panthalassan Coast (red star). Credit: Nate Smith
Evolutionary knowledge 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, showing that these crocodilian 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 generally) adapted independently to life along shores.
“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’ have led to a wider radiation of semi-aqueous groups,” said Smith.
B. eremicarminis specimen a) outline of the skeleton; b) color-coded interpretation of the skeleton. Credit: photo by Stephanie Abramowicz; drawing by Dr. Nicole Klein
Revealing 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 crocodilians (alligators, crocodilians, and gharials), descendants of pseudosuchian archosaurs such as B. eremicarminis. While today’s crocodiles are so similar that most people confuse them, their ancient relatives varied wildly in size and lifestyle. Evolutionary relationships B. eremicarminis and its relatives suggest that pseudosuchians achieved great diversity very quickly after the end-Permian mass extinction—the extent of which awaits discovery in the fossil record.
“The growing number of recent discoveries of Middle Triassic pseudosuchians suggests that there was an underappreciated amount of morphological and ecological diversity and experimentation early in the group’s history. While much of the public interest in the Triassic is focused on the origin of the dinosaurs, it’s really the pseudosuchians that were doing interesting things at the beginning of the Mesozoic,” said Smith.
Exploring ecology B. eremicarminis
The new species underscores the abundance of these ancient reptiles during the Triassic, from giants like Mambawakale ruhuhu to smaller animals as newly described B. eremicarminis, which probably reached around 5-6 feet in length. How long exactly B. eremicarminis he was and how he survived along the coast remains shrouded in the past. Only a few elements of the individual’s skull have been found, and similarly, any traces of how it fed and hunted are missing. What is clearer is that B. eremicarminis probably stuck pretty close to shore. Its well-preserved limbs are well developed without any signs of aquatic life such as fins 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, so they consulted with a member of the Fallon Paiute Shoshone tribe to decide on the appropriate name “Benggwi-Gwishinga,” a word that means “to catch fish” in Shoshone , was combined with the Greek word for Sobek, the crocodile-headed Egyptian god, to create a new genus, Benggwigwishingasuchus. Specific epithet eremicarminis translated as “desert song” in tribute to two NHMLAC supporters who share a passion for paleontology and the opera of the Southwest. So the whole title should be roughly translated as “Desert Song of the Fisherman Croc”.
Link: “New pseudosuchian from Nevada’s Favret Formation reveals that archosauriforms occupied coastal areas 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