145 Million-Year-Old Rat Teeth Offer Clues On Origins Of Modern Mammals
A student discovers two new fossil remains of teeth in England that came from ancient mammals believed to be the earliest known ancestors of human beings.
Grant Smith, an undergraduate student from the University of Portsmouth in England, stumbled upon two fossil teeth while he was sifting through samples at Durlston Bay on the Jurassic Coast of Dorset.
Durlston Bay is a site renowned for Cretaceous dinosaur fossils since fragments were first discovered there back in the 1800s.
Dr. Steven Sweetman, a research fellow at the University of Portsmouth, said that his "jaw dropped" when he first got a glimpse of the teeth because he realized immediately that he was looking at the remains of an Early Cretaceous mammal.
The Two Fossil Teeth
Scientists believe the two fossil teeth belonged to two different species of animals from the same group known as Eutheria. The animals are believed to be the oldest known ancestors of most modern mammals that are alive today, such as the pigmy shrew and the blue whale as well as humans.
Rat-Like Furry Creatures
Scientists say the ancient mammals were small nocturnal rat-like creatures that lived around 145 million years ago alongside dinosaurs. Their bodies were covered with fur, and their teeth were sharp that they could "cut and crush food."
One of the mammals may have been a burrower and snacked on insects, while the other one may have been a larger creature that ate plants. They were known to have branched out into two separate groups during the Jurassic and Cretaceous periods, and their origins can be traced back to the Triassic period.
Scientists named one of the species Durlstodon ensomi, after Paul Ensom, a local palaeontologist. The other mammal was named Durlstotherium newmani, after Charlie Newman, who is the landlord of a pub close to where the teeth were found. Both teeth were also named after Durlston Bay.
The findings were published in the journal Acta Palaeontologica Polonica.
Teeth Offer Clues On Origins Of Modern Mammals
Dr. Sweetman said that the new discovery could rewrite the history of the evolution of mammals. The findings suggest the origin of modern mammals stretches back much further in history.
"In the world of palaeontology there has been a lot of debate around a specimen found in China, which is approximately 160 million years old," said Dr. Sweetman.
"This was originally said to be of the same type as ours but recent studies have ruled this out. That being the case, our 145 million-year-old teeth are undoubtedly the earliest yet known from the line of mammals that lead to our own species."
160 Million-Year-Old Fossil Mammal
In 2011, a group of Chinese scientists has discovered a well-preserved fossil of a small shrew-like mammal in northeast China. Called Juramaia sinensis, the mammal is believed to have lived 160 million years ago.
This discovery has pushed back mammal evolution 35 million years and provided new insight about the earliest ancestors of placental mammals.