WASHINGTON (Reuters) – The branches of a well-built plant-eating mammal that inhabited Antarctica 250 million years ago provide the oldest known evidence that animals deployed in winter-like states to survive lean periods such as polar winters.
The interpretation of an artist shows the mammalian relative Lystrosaurus during the Triassic period in a hibernation-like state, released on August 27, 2020 by the University of Washington. Crystal Shin / distribution via REUTERS.
The study, published Thursday, focused on a square forager called Lystrosaurus, whose fossils have been found in China, Russia, India, South Africa and Antarctica. It was an early member of the evolutionary lineage that later gave rise to mammals.
The findings suggest that Lystrosaurus introduced a state of torpedo – a temporary decrease in metabolic activity – to cope with the long, perpetually dark winters in the Antarctic Circle when food was scarce, although the Earth was much warmer then than it is today. and the region was not ice-bound.
The findings also suggested that Lystrosaurus, which may have had hair, was warm-blooded.
Hibernation is a form of torpor found in warm-blooded animals such as certain bears, rodents, echidnas, hedgehogs and badgers.
Lystrosaurs, ranging from roughly the size of a bear to the size of a cow, had a turtle-like beak and had no teeth, except for a few ever-growing teeth protruding from its face useful for digging tasty roots and tubers. . These teeth had incremental growth marks visible in the form of dentine – the hard tissue that forms the bulk of a tooth – deposited in concentric circles such as tree rings.
The researchers examined branch cross-sections of six Lystrosaurus individuals from Antarctica and four from South Africa, away from polar conditions. The Antarctic teeth bore closely spaced, thick rings suggesting periods of less deposition during a hibernation-like state.
“Torpor is an incredibly common physiological phenomenon today,” said Harvard University paleontologist Megan Whitney, lead author of a study published in the journal Communications Biology.
“We expect torpor to be a frequently used adaptation for a very long time,” said Whitney, who worked on the research while attending the University of Washington. “However, this is difficult to test in the fossil record, especially deep back in time hundreds of millions of years ago.”
Such resilience may help explain why Lystrosaurs, which were millions of years before dinosaurs, survived the worst mass extinction in Earth’s history 252 million years ago, when the Permian period ended and the Triassic began. .
Report by Will Dunham; Edited by Sandra Maler
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