Your, cold blooded mammal

In the distant, dim interface between cold blooded reptiles, etc. and warm blooded mammals, it may not be found all cut and dried for the margins anymore.

Indications found of at least a couple hairy creatures of the late Jurassic age, of around 170-200 million years ago, are (proto?) types of mammalians not being warm blooded. It is likely they moved slowly, much like reptiles. Had a slow metabolism. Little evidence of endothermy.

This is a finding of special digging of Elis Newham of University of Bristol, UK. Mostly the finding is based on uncovered fossils. There were some 61 species studied. It is believed that some of them could live longer, due to cold blood, like 9-14 years. The fossils indicated these specimens were approximately weasel size. It is seen they had a bigger brain. It is not said if any branch of evolvement continued from these species.

This augments also the study of monotremes which concentrate on older mammalians, like what we call living fossils around Australia, e.g. platypus.