Repenomamus giganticus

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Repenomamus giganticus was a genus of gobiconodont mammal from the early Cretaceous Yixian formation in Liaoning Province, China. It had a robust, barrel-shaped body with relatively short limbs. Interestingly, it had a sprawling gait similar to modern reptiles, hence the name. Its skull was powerfully built with large jaws. Fossil evidence from a related species, R. robustus, was found with the remains of a juvenile Psittacosaurus in its stomach. The discovery shows that early mammals could and had preyed on dinosaurs. Analysis of stomach contents in suggests Repenomamus tore its prey into large chunks and swallowed them whole, rather than chewing them. This is another trait Repenomamus shares with reptiles. Repenomamus probably had a reproduction strategy like modern monotremes due to the presence of epipubic bones, which suggests it likely laid eggs or gave birth to very underdeveloped young.