Meet Megacauda: a chihuahua-sized fossil with a platypus behind and predator teeth

In a dark slab of 165-million-year-old rock from Inner Mongolia, University of Chicago paleontologist Zhe-Xi Luo's team found Megacauda sungei — a little mammal with a platypus-like rear built for swimming and a predator's head with sharp teeth (plus salamander bones in its belly), described in the journal Nature. X-ray imaging made the skeleton glow yellow out of the black stone. It's also some of the oldest evidence of mammals chewing and suckling.