Mamal which ate dinosaurs discovered

[wasteofo2]

http://news.bbc.co.uk/2/hi/science/nature/4165973.stm

An astonishing new fossil unearthed in China has overturned the accepted view about the relationship between dinosaurs and early mammals.

The specimen belongs to a primitive mammal about 130 million years old and its stomach contents show that it ate young dinosaurs called psittacosaurs.

The mammal with the dinosaur in its stomach belongs to a carnivorous mammal called Repenomamus robustus, which was about the size of an opossum.

"At first, we thought it was a placental mammal carrying an embryo. But then we looked more closely and saw it was a dinosaur," said co-author Dr Meng Jin, curator of palaeontology at the American Museum of Natural History.

"The position was also interesting; it was located in the lower left side of the fossil - exactly the position where the stomach is located in extant mammals."

Turns out that the stuff I learned as a kid about the only mamals during the time of the Dinosaurs being little mice who scurried away everytime a Dinosaur came along might not be totally true afterall.

Just imagine how many evolutionary gaps this thing must fill in, and how many wrong assumptions it must correct! I've always learned that the first mamals were just mice-like things, and all else evolved from them after the Dinosaurs went extinct. Now we know about this new predacious mamal from 135 million years ago that could have spawned so many of the creatures we know today.

 

[Phobos]

Cool, eh?
The first mammals appeared sometime around 165-200 million years ago (not sure what form...likely those mice/shrew things you're thinking of).
These mammals diverged into the marsupial & placental lineages when the dinos were still around (c. 125 million years ago).
As for the first primates, it seems there is some question whether or not they were around when the dinos were. The first unequivocal primate fossils were from after the dino's time (c. 55 million year ago) but there are some possible ones from 85 million years ago.
My impression is that the range of mammals was still fairly limited during the dino's reign and the more rapid diversification of mammals didn't occur until after the KT event.