LONDON, Nov. 7 (Xinhua) -- An undergraduate sifting through rocks collected from England's Jurassic Coast discovered the oldest ever fossils of mammals related to mankind, dating back 145 million years, it was revealed Tuesday.
Dr. Steve Sweetman, a research fellow at the University of Portsmouth, identified the fossils of teeth from small rat-like creatures that lived in the shadow of the dinosaurs, adding that student Grant Smith made the discovery.
Sweetman said: "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!"
He said the teeth are the earliest undisputed fossils of mammals belonging to the line that led to human beings.
Sweetman, whose primary research interest concerns all the small vertebrates that lived with the dinosaurs, added: "They are also the ancestors to most mammals alive today, including creatures as diverse as the Blue Whale and the Pigmy Shrew."
The findings were published Tuesday in the Journal, Acta Palaeontologica Polonica, in a paperco-authored by Sweetman.
Sweetman added: "The teeth are of a type so highly evolved that I realized straight away I was looking at remains of Early Cretaceous mammals that more closely resembled those that lived during the latest Cretaceous -- some 60 million years later in geological history.
Sweetman believes the mammals were small, furry creatures and most likely nocturnal. One, a possible burrower, probably ate insects and the larger may have eaten plants as well.
He said the teeth were of a highly advanced type that could 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," added Sweetman.
The teeth were recovered from rocks exposed in cliffs near Swanage which has given up thousands of iconic fossils.
Student Grant Smith said that he knew he was looking at something mammalian but didn't realize he had discovered something quite so special.
The university's Professor Dave Martill said: "I'm most pleased 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. 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."