Researchers have discovered a critter from the age of dinosaurs that rewrites our understanding of the history of early mammals.
The scientists said on Wednesday they found in Madagascar the fossil of a creature that resembles a big groundhog that likely lived some 66 million years ago, according to Reuters. At around 20 pounds, it was enormous compared to most other mammals of the Mesozoix Era.
Based on the preserved skull with a bizarre set of features, the species was an active plant eater with strong jaws, well-developed hearing, keen sense of smell and terrific eyesight under low light conditions.
It was called Vintana sertichi. Vintana means luck in the Malagasy language, according to Reuters.
In 2010, during excavations in Madagascar, the researchers found a 150-pound block of sandstone chock-full of fish fossils. They used a computerized tomography (CT) scan at Stony Brook University in New York state to look inside. Lucky for them, they saw more than just fish.
"We were astounded to see a mammal skull staring back at us on the screen," said Stony Brook University paleontologist David Krause, who led the study published in the journal Nature, according to Reuters.
"It was dawning on me that I was experiencing the most incredible bit of luck I had ever been part of," added Joe Groenke, Krause's technician and the first to view the CT images, according to Reuters.
Groenke spent half a year extracting the 5-inch long skull from the sandstone, one sand grain at a time.
Krause called Vintana the second-largest mammal known from the age of dinosaurs, when most mammals were shrew-sized, behind only the badger-like Repenomamus from earlier in the Cretaceous Period.
Vintana lived before the dinosaurs were wiped out by an asteroid that struck Earth, which paved the way for mammals to dominate the land, according to Reuters.
Vintana is a member of a group of primitive mammals called gondwanatheriansthern that lived on the southern supercontinent of Gondwana. Until now was known only from isolated teeth and jaw fragments.
The scientists determined that gondwanatherians were related to multituberculates, a group of rodent-like Mesozoic mammals that thrived on the northern continents, as well as another group called the haramiyidans.
"The new study of Vintana is a giant leap forward toward resolving the long-standing mystery of gondwanatherian mammals, which has puzzled paleontologists for decades," said Zhe-Xi Luo, one of the researchers. "Vintana is also a galvanizing discovery for the future decades. With features so remarkably different from those of other mammals previously known to science, this fossil tells us how little we knew about the early evolution of mammals-it will stimulate paleontologists to conduct more field exploration in order to advance the frontier of deep time history and evolution."
The findings are published in the journal Nature.