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Re: New Mesozoic mammal



On Wednesday, January 12, 2005, at 03:44 PM, Christopher Taylor wrote:
"Mesozoic mammals are commonly portrayed as shrew- or rat-sized animals that
were mainly insectivorous, probably nocturnal and lived in the shadow of
dinosaurs. The largest known Mesozoic mammal represented by substantially
complete remains is Repenomamus robustus, a triconodont mammal from the
Lower Cretaceous of Liaoning, China. An adult individual of R. robustus was
the size of a Virginia opossum. Here we report a new species of the genus,
represented by a skeleton with most of the skull and postcranium preserved
in articulation. The new species is 50% larger than R. robustus in skull
length. In addition, stomach contents associated with a skeleton of R.
robustus reveal remains of a juvenile Psittacosaurus, a ceratopsian
dinosaur. Our discoveries constitute the first direct evidence that some
triconodont mammals were carnivorous and fed on small vertebrates, including
young dinosaurs,

My question is, what diet was supposed for Repenomamus before discovery of one with stomach contents intact? And are there differences in dentition between the 2 species?


and also show that Mesozoic mammals had a much greater
range of body sizes than previously known. We suggest that Mesozoic mammals
occupied diverse niches and that some large mammals probably competed with
dinosaurs for food and territory."

Doesn't strike me as surprising - I recall a wildlife program showing ants kill baby crocodiles.