A 165-million-year-old fossil found in China has reportedly shown scientists how mammals developed a new way of swallowing during the age of the dinosaurs. The specimen is unusually well preserved: the animal’s body outline is visible, as are impressions of its skin and fur, and its hyoid bone was preserved as well. The animal, named Megacauda sungei, resembled a cross between a beaver and a platypus, with a flat, scaly tail and powerful swimming legs. It weighed an estimated 1 to 2 kilograms and was about 50 centimetres long, making it large for its time, when most mammals were no bigger than mice. The species has no living descendants.