Fossils push back origins of modern mammals
Common ancestor evolved over 200 million years ago
![drawing mouse-sized mammal Xianshou songae](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2014/09/mr_Fig.2.jpg?fit=860%2C460&ssl=1)
TREE HUGGER A newly identified mouse-sized mammal species, Xianshou songae, lived in Jurassic forests and has helped scientists redefine the mammalian family tree.
Zhao Chuang