Like most early nocturnal mammals, R. eurasiaticus was active at night. This reconstruction shows Rugosodon searching for food among ferns and cycads on the lakeshores in the darkness.
Cute Mammal Fossil
Furry Mammal Mama
Here, an artist's conception depicts a multituberculate in its natural habitat at the time of the dinosaurs.
What they found was a dog-size, strong-shouldered digger called Ernanodon. This mammal lived about 57 million years ago, after dinosaurs had died out and our furry ancestors had taken over. Ernanodon was known from one other fossil found in China, but that specimen is warped, and some archaeologists even thought it might be a fake. Shown here, a close relative, the modern-day pangolin (top) and the ancient Ernanodon antelios (bottom).
The fossil, discovered in what is now Liaoning Province in China, is the oldest evidence of the divergence of these "true" or placental mammals from their marsupial counterparts, and indicates the mammalian lineage was evolving faster than expected during the Jurassic Period.
For instance, like reptiles, the mammal's legs would have splayed out; it possessed a tiny spur on its rear feet that would've ejected venom, similar to egg-laying mammals called monotrenes; and its inner ear bone showed features that were more modern than the most primitive animals but not as advanced as modern mammals.