Fossils throw mammalian family tree into disarray

Fossils throw mammalian family tree into disarray

 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.