Jurassic fossil may help to solve evolution mysteries

A new Jurassic fossil from northeastern China may help to shed light on how multituberculates, the most evolutionarily successful and long-lived mammalian lineage in the fossil record, evolved, a study showed.

The 160 million-year-old fossil is a newly discovered species called Rugosodon euransiaticus, with the nearly complete skeleton indicating that its teeth were adapted to gnawing plants and animals alike and its ankle joints were highly adept at rotation.

These adaptations helped the mammals to thrive although threatened by dinosaurs and to survive beyond the dinosaurs' mass extinction 65 million years ago.

The study conducted by Chinese and American scientists was published in Science, one of the world's top scientific journals, on Friday.

Ji Qiang from the Institute of Geology under the Chinese Academy of Geological Sciences in Beijing said the Rugosodon was a nocturnal mammal that lived in a temperate climate on lakeshores in Liaoning province.

"It looked similar to a small rat or a chipmunk, and lived 160 million years ago as the oldest ancestor in the multituberculate family tree," Ji said, adding that multituberculates flourished across the planet from 170 million to 35 million years ago.

The discovery of the Rugosodon extends the distribution of certain multituberculates from Europe to Asia during the Late Jurassic period, the researchers said.