A team of scientists have named a new species of pseudosuchian archosaur – a group of living and extinct animals that includes modern crocodilians – from the Favret Formation in Nevada's fossil-rich Augusta Mountains.
Described in a study published in Biology Letters, the discovery of Benggwigwishingasuchus eremicarminis (B. eremicarminis) reveals that while giant ichthyosaurs ruled the world's oceans during the Middle Triassic (247.2 to 237 million years ago), it was ancient pseudosuchian archosaurs that dominated the shores.
The find rewrites the story of life along the world's coasts during the first act of the Age of Dinosaurs, says lead author of the paper Dr. Nate Smith, Curator of the Dinosaur Institute at the Natural History Museum of Los Angeles County (NHMLAC).
Despite its mountainous character today, the Favret Formation in central Nevada, USA, once lay beneath the eastern Panthalassan Ocean, an ancient superocean that surrounded the supercontinent Pangaea. Indeed, the area is known for fossils of sea-dwelling creatures such as ammonites and marine reptiles including giant ichthyosaurs. Finding the newly described B. eremicarminis came as a bit of a shock to the researchers.
“Our first reaction was: What the hell is this?” said co-author Dr. Nicole Klein, who was expecting to find marine reptiles. Instead, it was the partially articulated skeleton of B. eremicarminis that the scientists uncovered. The remains, which consist of parts of the skull as well as most of the spinal collumn, girdles and limbs, suggest the animal was probably around 1.5m in length.
"We couldn’t understand how a terrestrial animal could end up so far out in the sea among the ichthyosaurs and ammonites. It wasn’t until seeing the nearly completely prepared specimen in person that I was convinced it really was a terrestrial animal.”
Together with other pseudosuchians from the Tethys Ocean (now the Indian Ocean, Mediterranean Sea and the Eurasian inland marine basins), B. eremicarminis reveals that during the Middle Triassic these crocodile kin were also occupying parts of the Panthalassan Ocean and the Western Hemisphere, and thus coastal marine habitats around the world.
Interestingly, the study explains that these coastal species aren’t all from the same evolutionary group, suggesting that pseudosuchians (and archosaurs more widely) were independently adapting to life along Earth's shores.
“Essentially, it looks like you had a bunch of very different archosauriform groups deciding 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,” explains Smith.
“A growing number of recent discoveries of Middle Triassic pseudosuchians are hinting that an underappreciated amount of morphological and ecological diversity and experimentation was happening early in the group’s history. While a lot of the public’s fascination with the Triassic focuses on the origin of dinosaurs, it’s really the pseudosuchians that were doing interesting things at the beginning of the Mesozoic."
"While a lot of the public’s fascination with the Triassic focuses on the origin of dinosaurs, it’s really the pseudosuchians that were doing interesting things."
The new species Benggwigwishingasuchus eremicarminis translates broadly as 'fisherman croc’s desert song'. The first half of the name Benggwigwishingasuchus is a combination of the word 'Benggwi-Gwishinga', meaning 'catching fish' in Shoshone, the language of the Augusta Mountains' Fallon Paiute Shoshone Tribe, and the Greek word for Sobek, the Egyptian crocodile-headed god. While eremicarminis translates to 'desert song', paying homage to two supporters of NHMLAC who have a passion for palaeontology and opera.
The new species underlines the great number of these ancient reptiles during the Triassic, from huge animals such as Mambawakale ruhuhu to smaller animals such as the newly described B. eremicarminis.
Because only a few parts of the B. eremicarminis specimen were found, clues to how it fed and hunted are few and far between. However, the researchers say that the well-developed limbs, which have no signs of aquatic living, such as flippers or altered bone density, suggest that B. eremicarminis likely stuck close to the shore.
Find out more about the study: A new pseudosuchian from the Favret Formation of Nevada reveals that archosauriforms occupied coastal regions globally during the Middle Triassic.
Main image: Benggwigwishingasuchus eremicarminis on the Panthalassan Ocean coast. Credit: Jorge Gonzalez
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