HOW MAMMALS PREVAILED.

SCIENCE museums; MAMMALS; UNGULATES; EOCENE Epoch; PALEOCENE Epoch; ANKLE; HUMAN fingerprints

But this burgeoning would have to wait until the next time interval after the Paleocene: the Eocene, when the archaic placentals slowly declined and the modern placental groups - including horses, bats and whales - took over the planet. As ecosystems recovered in the earliest Paleocene, many of the mammals that started to multiply were eutherians, the placental antecedents that were once bit players in the Cretaceous. Some of the archaic species, such as taeniodonts, might have stemmed from Cretaceous eutherian ancestors and thus would be among the most primitive placentals on the trunk of the family tree. The relative brain sizes of the archaic placentals were laughably small compared with not only those of today's mammals but even those of the Cretaceous species living with the dinosaurs. [Extracted from the article]

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