British student discovers fossil of 'earliest ancestors' of humans

A British student discovered fossilized teeth that are believed to be from the "earliest ancestors" of humans, two rat-like mammals that lived some 145 million years ago, scientists said on Tuesday.

The two teeth are the "earliest undisputed fossils of mammals belonging to the line that led to human beings," said the scientists at the University of Portsmouth.

"They are also the ancestors to most mammals alive today, including creatures as diverse as the blue whale and the pygmy shrew," they said.

Steve Sweetman, a research fellow, co-authored a paper on the findings in the Polish-based quarterly journal Acta Palaeontologica Polonica.

Sweetman identified the teeth from two separate species, but he said student Grant Smith made the discovery while examining fossils collected in Dorset on the southern English coast.

"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.

"Quite unexpectedly he found not one but two quite remarkable teeth of a type never before seen from rocks of this age," he was quoted as saying.

From analysing the teeth, Sweetman believes that one of the mammals probably ate insects and the larger one may have also eaten plants.

Smith's supervisor, professor of Palaeobiology Dave Martill, said he was happy 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."