(CN) — Archeologists have uncovered another puzzle piece of the history behind prehistoric mammals following the discovery of a well-preserved fossil of a curious little creature whose name directly translates to “crazy beast.”
According to a 20 year-long study, published Thursday in the Journal of Vertebrate Paleontology, the fossil named Adalatherium, fills in some important blanks about ancient mammals from the supercontinent of Gondwana 66 million years ago.
The study was conducted by a team of 14 international researchers, led by David Krause from the Denver Museum of Nature & Science, and Simone Hoffmann from the New York Institute of Technology.
They announced the discovery in April in the journal Nature, and released another feature in the Society of Vertebrate Paleontology Memoir series, which highlights the most noteworthy fossils of each year.
In its prime, this fascinating mammal lived on what is now known as Africa, South America, Australia, Antarctica, the Indian subcontinent and the Arabian Peninsula. The researchers struck an information gold mine with this fossil, as it is the best representation of mammals from the southern hemisphere pre-mass extinction.
"Adalatherium is an important piece in a very large puzzle on early mammalian evolution in the southern hemisphere, one in which most of the other pieces are still missing," Hoffmann said.
The crazy beast has such mismatched bone structure, it was difficult to piece together and render an actual image. Its recreation looks similar on the surface to a common badger, but the authors emphasize how confusing and anomalous its contents really are.
It had more trunk vertebrae than the average mammal, indicating strong back muscles that likely made it wiggle side to side as it walked, and it just gets weirder from there.
It had strong back legs that sprawled-out on either side, but skinnier front legs that were positioned under its body, making the researchers wonder how the mammal even walked.
The creature had front bucked teeth like a rabbit but alien-like back teeth not seen in any other mammal before. And it seems to have had an unexplained hole in it’s head just above the snout, also never before seen in any other mammal and its purpose unknown.
Needless to say, the researchers had a lot to unpack.
They suspect that due to the strong claws and back legs, the Adalatherium would have been excellent at digging, while the front legs suggested it could have also been a quick runner.
The researchers describe the teeth as plain bizarre, with front teeth suggesting it may have been a herbivore, but the most unusual back teeth that don’t match any known records.
The authors note that if the teeth were the only part of the Adalatherium uncovered, they couldn’t have made the connection and the crazy beast would have remained hidden from the world.
Furthermore, the hole above the snout is a remarkable mystery, and while it may have been covered with cartilage, there is simply no way of knowing.
"Adalatherium is simply odd. Trying to figure out how it moved, for instance, was challenging because its front end is telling us a completely different story than its back end,” Hoffman said.
The fossil indicates that the animal was about the same size as an opossum, and weighing just under 7 pounds, it would have been one of the largest mammals of its time. It lived alongside the dinosaurs 145-66 million years ago on what is modern day Madagascar.
It is believed to be descended from a strange group of prehistoric, herbivorous mammals called gondwanatherians, the first evidence of which was discovered approximately 40 years ago. Until the Adalatherium came along, scientists only knew of these mammals from a handful of teeth, jaw fragments, and a partial cranium, and they were at a loss about how they evolved from other mammals.
"Knowing what we know about the skeletal anatomy of all living and extinct mammals, it is difficult to imagine that a mammal like Adalatherium could have evolved; it bends and even breaks a lot of rules," Krause said.
A possible explanation as to why the Adalatherium is so chaotic is that at the time of its death, Madagascar had already separated from Gondwana. It had been isolated from nearby continents, including Africa and India, for millions of years, long enough for its inhabitants to evolve separately from other mammals.
"Islands are the stuff of weirdness," said Krause, "and there was therefore ample time for Adalatherium to develop its many extraordinarily peculiar features in isolation."
The authors say that the crazy beast proves how much is still unknown about early mammals in the southern hemisphere.
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