An artistic rendering shows what the newly discovered toothed turtle species Sichuanchelys palatodentata might have looked like. Photo by Lida Xing
FRIBOURG, Switzerland, Nov. 8 (UPI) -- Scientists thought turtles with teeth disappeared around 190 million years ago, but new evidence suggests the toothed reptiles stuck it out for an extra 30 million years.
Today, turtles are toothless; they chomp their veggies using the hard edges of their beak-like jaws. Many of their ancient relatives, however, boasted teeth.
A group of researchers found 160 million-year-old fossil evidence of these toothed turtles at the famed Xinjiang site of Wucaiwan in Western China, a paleontological dig site known for its wealth of dinosaur fossils.
The researchers described their findings in a new paper published this week in the journal BMC Evolutionary Biology.
"Scientists had previously known that the earliest turtles still had teeth in their palates, a primitive feature they inherited from their reptilian ancestors," lead study author Walter Joyce, a paleontologist from the University of Fribourg, Switzerland, explained in a news release. "Previously, the last toothed turtle, however, was known from 30 million years older rocks. It is therefore a great surprise to find a toothed turtle that survived even longer."
Researchers say their discovery will help scientists better understand the evolution, distribution and organization of the chelonian family tree, the lineage that includes all turtles, living and extinct.
The fossils uncovered by Joyce and his colleagues represent a new species, which scientists named Sichuanchelys palatodentata.
"Our analysis revealed that the new turtle is the closest known relative of a large terrestrial turtle, Mongolochelys efremovi, that lived almost 100 million years later in central Asia," said Márton Rabi, a researcher at the University of Tübingen in Germany. "It seemed a bizarre turtle that previously had no known close relatives, but now we see that it represents the final links of a long lineage that persisted throughout Asia for much of the Mesozoic."
The new research also revealed a distinct pattern of turtle diversification and distribution defined by the breakup of the continents 175 million years ago.
"Our analysis reveals that the initial diversification of turtles was controlled by the breakup of the super continent Pangea during the Jurassic to Cretaceous," added Joyce. "Each continent thereby developed its own unique turtle fauna, like the extinct turtle lineage we newly discovered from Asia."