145 Million Years Old Fossil Teeth of Early Mammals Shocks Archaeologists, 'A Jaw-Dropping Moment'
Human ancestors had an adventurous trajectory on Earth, and their fossils help experts understand this trajectory. In 2015, a team of researchers found certain remains in southern England that gave them insights regarding an important group of now-extinct creatures, stated National Geographic.
These remains belonged to two newfound species of early mammals and were located on the Jurassic Coast of Dorset. Researchers believe these are some of the oldest known fossils from the line of Eutherian mammals. Examinations unveiled that the fossils were 145 million years old. Researchers were stunned to make this discovery in the form of two ancient teeth. "It was a jaw-dropping moment; I was shocked," said Steve Sweetman, a mammal-tooth specialist and a research fellow at the University of Portsmouth. "These were the sorts of things you’d expect to see in the Upper Cretaceous, not way down in the base of the Cretaceous."
The two ancient teeth belonged to two different creatures. The smaller one was named Durlstotherium while the larger one was named Durlstodon. Researchers claim that the ancient mammals were rat-like in size and lived alongside dinosaurs, stated Phys.org. The association of the fossils with Eutherian mammals is important for researchers because this group of mammals eventually led to modern-day humans.
Along with humans, these mammals are also ancestors of the Blue Whale and the Pigmy Shrew. Undergraduate student, Grant Smith, spotted the teeth at the site. "Grant was sifting through small samples of earliest Cretaceous rocks collected on the coast of Dorset as part of his undergraduate dissertation project in the hope of finding some interesting remains. Quite unexpectedly he found not one but two quite remarkable teeth of a type never before seen from rocks of this age. I was asked to look at them and give an opinion and even at first glance my jaw dropped," Sweetman shared.
Sweetman claimed that the remains which dated back to the Early Cretaceous period were similar in appearance to the mammals that had been recorded in the Upper Cretaceous, which happened some 60 million years later in geological history. Before this study, there was some speculation that a 160 million-year-old specimen found in China was the oldest known fossil of an eutherian mammal, but recent examinations have proved the assertion to be false. As per the team, the specimen collected by them from Dorset is the earliest known specimen of Eutherian mammals.
Researchers believe that the Eutherian mammals living alongside dinosaurs were nocturnal and had lots of furs. The smaller one could be a borrower who primarily lived on insects, while the larger one ate some plants. "The teeth are of a highly advanced type that can pierce, cut, and crush food. They are also very worn which suggests the animals to which they belonged lived to a good age for their species. No mean feat when you're sharing your habitat with predatory dinosaurs," Sweetman shared.
Experts think this fossil proves that the history of Eutherian mammals could be older than previously believed by researchers, stated National Geographic. "There may well be eutherians coming from other parts of the world from older rocks," said Sweetman. "We’d expect there to be; we just haven’t found them yet."