Lizard that lived 260 million years ago was earliest turtle

Eunotosaurus, about 30 centimetres long, possessed wide and flat ribs that gave it a distinctly rounded and turtle-like profile.

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WASHINGTON // It was a creature that one scientist said resembled “a strange, gluttonous lizard that swallowed a small Frisbee”.

But a sophisticated skull analysis showed that this reptile, called Eunotosaurus africanus, which lived in southern Africa 260 million years ago, is the earliest-known turtle, even though it had no shell, researchers said.

Eunotosaurus, about 30 centimetres long, possessed wide and flat ribs that gave it a distinctly rounded and turtle-like profile. It mixed features of its lizard-like ancestors with emerging turtle-like characteristics that evolved over tens of millions of years into familiar turtle traits, the researchers said.

“Think of your neighbourhood box turtle, but much more flattened and with scaly skin and a long tail,” said New York Institute of Technology’s Prof Gaberiel Bever. “And teeth, it had a mouthful of them.”

Only later did turtles become toothless. Eunotosaurus lived during the Permian period 20 million years before Pappochelys, a creature from Germany that in June was identified as the earliest-known turtle, and 30 million years before the first dinosaurs. The earliest turtle with a fully formed shell lived about 210 million years ago.

Eunotosaurus fossils were first unearthed in South Africa in the late 19th century. There has been a long debate about whether it was part of the turtle lineage.

Prof Bever’s team used advanced scanning technology to perform a detailed analysis of its skull anatomy, digitally dissecting each cranial bone in four fossil specimens, to help demonstrate Eunotosaurus was the oldest-known member of the turtle group.

“Where turtles came from, evolutionarily speaking, and how they are related to the other major groups of living reptiles – lizards, snakes, crocodiles and birds – has been a topic of vigorous debate for as long as we’ve had a theory of evolution,” Prof Bever said.

More insight into the turtle lineage came in 2008 when scientists described a primitive turtle from 220 million years ago called odontochelys from China.

“Turtles have been missing their archaeopteryx, their missing link to the rest of the vertebrate tree, since Darwin told us that we should be looking for one,” said Prof Bever, mentioning the oldest-known bird.

* Reuters