Paleontologists have uncovered the first postcranial remains — skeletal remains apart from the skull — of Vintana sertichi, the largest known mammal from the Mesozoic (252 to 66 million years ago) of the supercontinent Gondwana.
Vintana sertichi is a groundhog-like animal that lived in what is now Madagascar during the Late Cretaceous epoch, about 70-66 million years ago.
The ancient creature was a large-eyed herbivore that was agile, with keen senses of hearing and smell.
It had a body mass of about 9 kg, almost three times the size of an adult groundhog.
Previously, Vintana sertichi was only represented by a fossilized skull, which Dr. David Krause from Denver Museum of Nature & Science and colleagues described in 2014.
Several years later, in 2020, they uncovered the nearly complete skeleton of a strange, possum-sized gondwanatherian called Adalatherium hui.
Until now, Adalatherium hui’s fossilized skeleton represented the only postcranial remains in the gondwanatherian fossil record.
Now, Dr. Krause and his colleague, New York Institute of Technology’s Dr. Simone Hoffmann, present additional gondwanatherian postcranial evidence and reveals that a vertebra fossil from the Cretaceous of Madagascar was once a tailbone of Vintana sertichi.
Using a micro-computed tomography scanner, they scanned the vertebra and compared the virtual surface files to the tail vertebrae from Adalatherium hui.
They found that the vertebra was very similar to that of Adalatherium hui, the second largest Mesozoic mammal from Madagascar, but much larger — nearly 40% larger, to be exact.
This size put it solidly within the range to classify it as Vintana sertichi.
“While the remains represent only an isolated vertebra from Vintana sertichi’s larger skeleton, its discovery provides key information about the gondwanatherian lineage,” Dr. Hoffmann said.
“Gondwanatherians had uniquely short tail vertebrae and this new discovery tells us that the tail of Vintana…
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