Fossil find suggests this ancient reptile lurked on land, not in the water

Exquisitely preserved specimen may overturn ideas about spiny creature’s home

Eusaurosphargis dalsassoi

ROUND AND ROUGH  A round body and stiff, short legs revealed in a complete fossilized skeleton of Eusaurosphargis dalsassoi (shown) suggests the creature wasn’t sleek enough to swim. 

Beat Scheffold/Palaeontological Institute and Museum/University of Zurich, Switzerland

A round belly, stubby feet and a tapering tail made one armored reptile a lousy swimmer. Despite earlier reports, Eusaurosphargis dalsassoi might not have swum at all, scientists now say.

E. dalsassoi was first identified in 2003. Fossils were found near Monte San Giorgio at the Swiss-Italian border alongside the remains of marine reptiles and fish that lived roughly 240 million years ago. That association led scientists to conclude the creature was aquatic. But a complete skeleton of E. dalsassoi unearthed in 2002 in the Swiss Alps and recently assembled contradicts that idea.

At just under 20 centimeters long, the fossil, probably of a youngster, shows that E. dalsassoi widened at the stomach and slithered forward with stiff elbow and knee joints and spadelike claws. That’s not a swimmer’s build, paleontologist Torsten Scheyer of the University of Zurich and colleagues report June 30 in Scientific Reports.

Armed with rows of small spikes along its back and spear-shaped plates framing its head, sides and tail, the animal resembled today’s girdled lizards. The researchers speculate that this particular E. dalsassoi died on a beach and then got washed into the ocean.

LAND LIVING Eusaurosphargis dalsassoi, an ancient lizardlike critter (illustrated), wouldn’t swim well, scientists now say, arguing the creature’s style of motion and protective coverings were more suited to land. T. Scheyer/Palaeontological Institute and Museum/University of Zurich, Switzerland
photo of Ashley Yeager

Ashley Yeager is the associate news editor at Science News. She has worked at The Scientist, the Simons Foundation, Duke University and the W.M. Keck Observatory, and was the web producer for Science News from 2013 to 2015. She has a bachelor’s degree in journalism from the University of Tennessee, Knoxville, and a master’s degree in science writing from MIT.

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