Two fossils have got palaeontologists scratching their heads about where to place an enigmatic group of animals in the mammalian family tree. A team analysing one fossil suggests that the group belongs in mammals, but researchers looking at the other propose that its evolutionary clan actually predates true mammals. The situation begs for more analysis, more fossils, or both, experts say.
The fossils represent previously unknown species, described today in Nature1, 2. Both are members of the haramiyids, a group of animals that first appeared around 212 million years ago and that researchers first recognized in the late 1840s. Until now, the creatures have been known only from isolated examples of their distinctive teeth — which have some rodent-like features — and a single fragmentary jawbone. But both fossils described today include not only the distinctive teeth, but also vertebrae and bones from the limbs, feet and tails.To read more, click here.