The rocks along the Jurassic Coast of southern England have yielded the remains of some the earliest known mammals, which lived alongside the dinosaurs some 145 million years ago. Photo by Mark Witton/University of Portsmouth

Nov. 7 (UPI) -- Paleontologists have discovered the remains of the earliest mammals belonging to the lineage that evolved modern humans. The fossils were found along the coast of southern England.

Researchers from the University of Portsmouth discovered a pair of small teeth while sifting through rocks. The teeth belonged to a small rat-like creature that scurried along the forest floor 145 million years ago, while giant dinosaurs were tromping overhead.


The mammal is the earliest undisputed member of the lineage that yielded Homo sapiens.

The fossil teeth were found by undergraduate student Grant Smith, but they were identified by Steve Sweetman, a research fellow at Portsmouth.

RELATED Mammals became more active during the day after the dinosaurs disappeared

"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," Sweetman said in a news release. "Quite unexpectedly he found not one but two quite remarkable teeth of a type never before seen from rocks of this age."

The discovery landed Smith's name in the journal Acta Palaeontologica Polonica.

"Steve made the connection immediately, but what I'm most pleased about is that a student who is a complete beginner was able to make a remarkable scientific discovery in palaeontology and see his discovery and his name published in a scientific paper," said Dave Martill, professor of palaeobiology.

Sweetman recognized the teeth as being uniquely evolved, recalling the teeth of mammal species that wouldn't appear in the fossil record for another 60 million years. It was immediately clear they belonged to an early mammal species.

"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," Sweetman said. "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."

Sweetman believes the rat-like creature to which the teeth belonged was small, furry and nocturnal. The teeth were capable of piercing and crushing food, which suggests the small mammal likely ate both insects and plants. The two teeth were also quite worn, suggesting the specimen lived to a decent age.

RELATED Crocodile fossils suggest giant reptiles emerged earlier than previously thought

The teeth were found among rocks collected from the cliffs near Swanage, a town in the south east of Dorset. The rocks there have yielded thousands of unique fossils through the years.

"The Jurassic Coast is always unveiling fresh secrets and I'd like to think that similar discoveries will continue to be made right on our doorstep," said Martill.