Repenomamus (Cretaceous)

Repenomamus ("Reptilian mammal" from Latin) is the largest early Cretaceous period mammal lived about 125 million years ago. Its fossils were unearthed in China, in the Liaoning province. It bore a striking resemblance to the present "Tasmanian devil".
The ancient rodent total length was one metre and the body was 1 m long. Paleontologists believe that the beast was an average runner due to the features of the limb structure - the shoulder and limb bones formed a wide-angle relative to joints. Fore and hind limbs were proportionally short for its body size. Moreover, it had plantigrade feet.
Their diet definitely included meat as a specimen of R. Robustus was discovered with the fragments of dinosaur preserved in its stomach. This proves that mammals of that period were carnivorous and fed on other vertebrates. Though it is unknown whether they ate carrion or live prey.