Benggwigwishingasuchus eremicarminis on the shores of the Pantalasan Ocean. Credit: Jorge Gonzalez
Newly discovered Triassic crocodilian relative shows that pseudozoan archosaurs inhabited global coastal areas, greatly enriching our understanding of Mesozoic marine ecosystems.
Researchers have discovered a new kinds of an extinct crocodilian relative from the Triassic Favret Formation of Nevada, USA. The species named Benggwigwishingasuchus eremicarminis, reveals that a lineage of ancient crocodilians known as pseudozoan archosaurs dominated the globe’s shores from the Middle Triassic, between 247.2 and 237 million years ago. This finding, detailed in a study published July 10 in Biology Lettersis changing our understanding of coastal ecosystems during the early age of the dinosaurs.
“This exciting new species demonstrates that pseudosuchians inhabited coastal habitats worldwide during the Middle Triassic,” said Dr. Nate Smith, lead author of the report, and Gretchen Augustin, director and curator of the Dinosaur Institute at the Museum of Natural History. Los Angeles County.
Revealing pseudozoan diversity
The majority of fossils from the Triassic eastern Pantalasan Ocean, 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 of 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 the ichthyosaurs and ammonites. It was only when I saw the almost fully prepared specimen in person that I was convinced that it was indeed a land animal.”
Map of the Middle Triassic oceans and archosauriforms described from the East Coast (yellow dots), as well as the new species B. eremicarminis from the Pantalasan Coast (red star). Credit: Nate Smith
Evolutionary insights from fossil discoveries
Pseudozoan archosaurs have been found in fossils from the shores of the ancient Tethys Ocean, but this is the first coastal representative from the Pantalasan Ocean and the Western Hemisphere, revealing that these crocodilian relatives were present in coastal environments around the world during the Middle Triassic. Interestingly, these coastal species are not from the same evolutionary group, suggesting that pseudosuchians (and archosauriforms more broadly) adapted independently to coastal life.
“Essentially, it looks like you had a bunch of very different groups of archosauriforms that decided to dip their toes in the water in the middle Triassic.” “Interestingly, it doesn’t appear that many of these ‘independent experiments’ have led to wider broadcasts of semi-aquatic groups,” Smith said.
Specimen of B. eremicarminis (a) skeletal view; (b) color-coded interpretation of the skeleton. Credit: Photo by Stephanie Abramovich; drawing by Dr. Nicole Klein
Revealing 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 (alligators, crocodilians, and gharials), descendants of pseudosuchian archosaurs such as B. eremicarminis. While today’s crocodiles are similar enough to be confused with one another by most people, their ancient relatives differed enormously in size and lifestyle. The evolutionary relationships of B. eremicarminis and its relatives suggest that pseudosucchis achieved great diversity very quickly after the end-Permian mass extinction—the extent of which awaits discovery in the fossil record.
“The increasing number of recent discoveries of Middle Triassic pseudosuchians suggests that an underestimated amount of morphological and ecological diversity and experimentation occurred early in the group’s history. Although much of the public’s fascination with the Triassic has focused on the origin of the dinosaurs, in fact pseudosuchians were doing interesting things in the early Mesozoic,” Smith said.
A study of the ecology of B. eremicarminis
The new species highlights the multitude of these ancient reptiles during the Triassic, from giants such as Mambawakale ruhuhu to smaller animals such as the newly described B. eremicarminis, which probably reaches about 5–6 feet in length. What exact time B. eremicarminis it was and how it survived on the shores remains shrouded in the past. Only a few elements of the individual’s skull were found, and any clues about how it ate and hunted are missing. It is more clear that B. eremicarminis probably stayed 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 paid respect to the original human inhabitants of Mount Augusta, where the specimen was found, so they consulted with a member of the Fallon Paiute Shoshone tribe to decide on an appropriate name. “Benggwi-Gwishinga,” a word meaning “fish-catching” in Shoshone, was combined with the Greek word for Sobek, the crocodile-headed Egyptian god, to create the new genus, Benggwigwishingasuchus. The particular epithet eremicarminis translates to “desert song,” in honor of two NHMLAC supporters who have a passion for paleontology and the opera of the Southwest. Thus, the full name should be roughly translated as “Desert Song of the Fisherman Croc”.
Reference: “New pseudosuchian from Nevada’s Favret Formation reveals that archosauriforms inhabited coastal regions worldwide 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
