The fossils of the nocturnal mammal were discovered on the Jurassic Coast of Dorset, by paleontologists from the University of Portsmouth in the UK.
The animal is the earliest in the line that evolved into humans, and branched off into creatures as diverse as blue whales and pigmy shrews, according to a study published in the journal Acta Palaeontologica Polonica.
The new species has been named 'Durlstotherim newmani' - after an amateur paleontologist and pub owner Charlie Newman, who helped scientists collect the new specimens.
"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," said Steve Sweetman, research fellow at Portsmouth University.
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"The teeth are of a highly advanced type that can pierce, cut and crush food," Sweetman was quoted as saying by 'The Telegaph'.
Mammal teeth evolved over time, from very simple ones that were not very efficient, to molar-like ridged teeth which could tear, chew and grind food very easily.