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 The scientists on Wednesday announced the discovery of the
oldest-known turtle, an 8-inch (20-cm) Triassic Period reptile
combining traits of its lizard-like ancestors with a set of emerging
turtle-like features.
They named it Pappochelys, meaning "grandfather turtle," owing to
its position at the base of the turtle family tree.
"Pappochelys indeed forms a missing link for two reasons. It is far
older than all so far known turtles. And its anatomy is more
primitive in many features, showing the ancestral condition of
various body regions," said paleontologist Rainer Schoch of
Germany's State Museum of Natural History Stuttgart.
It is 20 million years older than the previous earliest-known
turtle, Odontochelys from China. While Odontochelys boasted a
rudimentary shell on its back, Pappochelys bore only the beginnings
of this characteristic turtle trait that evolved in many steps over
tens of millions of years.
"The belly armor is composed of thick, rib-like bones that are
beginning to fuse to each other in many places," said paleontologist
Hans-Dieter Sues of the Smithsonian Institution's National Museum of
Natural History in Washington, calling this "an important stage in
the evolution of the turtle shell."
Pappochelys, known from 18 fossil skeletons, had a long tail, broad
trunk, and, rather than a beak as in later turtles, a lizard-like
skull with numerous peg-like teeth suitable for eating insects and
small lizards.
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It resided alongside a freshwater lake and may have used its tail
for swimming and legs for steering in the water.
Schoch said Pappochelys, as a transitional creature between
lizard-like ancestors and later turtles, provides a much clearer
picture of turtle evolution.
"Transitional creatures are the most important contribution that
paleontology can make to the study of evolution. They are often
unexpected and show surprising features," Schoch said. "They show
how complicated structures like the skull or turtle shell formed
step by step, and also give evidence on the sequence of evolutionary
steps."
Pappochelys lived 10 million years before the first dinosaurs, but
plenty of danger existed. The lake's largest predator was the
16-foot (5-meter) amphibian Mastodonsaurus. The 20-foot (6-meter)
terrestrial croc relative Batrachotomus prowled the land.
The research appears in the journal Nature.
(Reporting by Will Dunham)
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