The two teeth are from small, rat-like creatures
Researchers say fossils of the oldest mammals related to mankind have been discovered in England.
The find was made on the Jurassic Coast of Dorset.
The two teeth are from small, rat-like creatures that lived 145 million years ago.
They are the earliest, undisputed fossils of mammals belonging to the line that led to human beings.
They would have lived in the shadow of the dinosaurs.
They are also the ancestors to most mammals alive today, including creatures such as the Blue Whale and the Pigmy Shrew.
The findings have also been published today in the journal, Acta Palaeontologica Polonica.
Dr Steve Sweetman, research fellow at the University of Portsmouth, identified the teeth.
But it was undergraduate student, Grant Smith, who made the discovery.
Dr 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.
"The teeth are of a type so highly evolved that I realised 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.
"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.
"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."
Dr 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 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".
The teeth were recovered from rocks exposed in cliffs near Swanage, which has given up thousands of iconic fossils.