Researchers have discovered a jaw fragment from the world’s oldest rodent which inhabited Greenland over 215 million years ago.
The team of Polish researchers published their findings in the peer-reviewed journal ‘Proceedings of the National Academy of Sciences of the United States of America’.
The research began in 2014 when Grzegorz Niedzwiecki of Uppsala University in Sweden found a fragment of an animal’s lower jaw.
The double-rooted tooth was in the mandible of a distant ancestor of the shrew that lived in Greenland over 215 million years ago.
Professor Tomasz Sulej of the Polish Academy of Sciences (PAN), who headed the scientific expedition to Greenland, said the fragment was the oldest double-rooted molar ever found.
The professor added that the discovery unearthed a new species of prehistoric rodents that could be a “missing link” in the evolution of rodents’ diets, signalling a transition from insect-based food to a vegetarian diet.
Professor Sulej said: “The form that we’ve discovered displays teeth that signal the transition from insect-eaters to herbivorous mammals.
“It is a discovery of exceptional rarity within palaeontology and one that demonstrates a smooth transition from the thin teeth of insect-eating prototheria to the broad and flat tooth coronal of herbivorous mammals.”
Experts carried out tests between single-rooted and double-rooted teeth which proved that the latter was “more durable at the end of the day”, according to Maksymilian Sienkiewicz of the Warsaw University of Technology.
Scientists decided to name the world’s oldest rodent species Kalaallitkigun jenkinsi.
‘Kalaallitkigun’ means ‘Greenland’ in the language of the island’s original inhabitants while ‘jenkinsi’ refers to Harvard University professor Farish Alston Jenkins who carried out numerous expeditions to the Arctic and Greenland before his death in 2012.
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