Rugosodon comes from a group of multituberculates, extinct rodent-like mammals from this time period. They get their name from their bumpy back teeth, hence “wrinkly tooth”.
This rat lived alongside the dinosaurs around 170 million years ago. It’s considered the earliest ancestor of modern rats and it made its home in China, or at least that’s where the only fossils have been found.
The complete set of fossils were found by a large multi-national team from the University of Chicago, the Chinese Academy or Geological Sciences, along with the Beijing Museum of Natural History and additional help and funding from the Carnegie Museum of Natural History of Pittsburgh.
A Rare Tooth Find
One of the truly amazing things about this find is that the bones were discovered in their entirety as a complete set of biological remains. It was also found intact as opposed to how usual finds are discovered, spread out over a large area, or buried underneath each other beneath multiple layers of rock and soil. It’s very rare for scientists to find a whole specimen and the benefits to then researching the find are immeasurable, due to the fact that they can get almost a complete picture of the animal’s biology, diet and physical traits and attributes.
It may come as a bit of a surprise that this mammal could have survived alongside of an environment full of ravenous, giant meat-eating predators, but the researchers say this new find can explain how. It had large rodent-like front incisors and multifunctional molars and premolars that would have made their diet accommodating to the various small animals, insects, worms, nuts, seeds, or different plant materials that were available to them.
It also had flexible ankle bones which allowed it to be very fast, and also allowed it to turn at sharp degrees while running at full speed. This super-rat was also able to climb trees, jump both straight up and forward, or even dig tunnels. All important abilities when being chased by a hungry dinosaur. It was around 6.5 inches which is about the same size as the modern rat but its abilities were what helped it survive for so long.
Zhe-Xi-Lou, one of the scientists who discovered the fossil and is now studying the remains, says that the discovery provides insight on the survival success of early mammals. “The superb feeding function, together with versatile locomotion adaptions, explains why early mammals were so successful and diverse. Now, we have a sense of what they started off with, thanks to the discovery of rugosodon.”