Mammalia

From Dinopedia

Mammals (Linnaeus, 1758) are a group of endothermic animals characterized by hair/fur, and providing their young with milk for nutrititon, from sophisticated milk glands.

[edit] Mammal Origins

Mammals first evolved around 220 million years ago, during the Late Triassic period, at around the same time as the dinosaurs. They evolved from a group of reptiles known as therapsids, or "mammal-like reptiles", which were characterized by sharing both reptiles and mammalian qualities. Mammals stayed small throughout the Mesozoic, although some, such as Didelphodon, could grow to the size of cats. But then, with the K-T Extinction event, which wiped out the dinosaurs, mammals exploded into the neiches the dinosaurs left vacant. Although, for a short time, Terror Birds, such as Diatryma, took on the roles of the extinct theropods, they were soon ousted by faster, more efficient mammalian predators, such as Hyaenodon. Mammals have continued to flourish to this day, being considered the dominant order of life.