In 1998 the fossilized jaws of a mammal were discovered at a ranch in Montana (USA).
This discovery can change the theory of mammal creation. Richard Cifelli, a paleontologist at the University of Oklahoma Museum of Natural History, analyzed fossils and published the results in the journal "Nature". It is the fossil of a mammal who lived in the Cretaceous 110 million years ago, at the same time as those found previously in Asia. This implies a renewal of theories about the origin of mammals.
In view of the data obtained to date, it was considered that mammals were born in Asia and went to America. Cifelli says that this latest discovery leaves open the question of whether mammals also emerged in America.