Cross references: Mammals Sauropsids Labyrinthodonts Permian Discontinuity Subcortical Brain Therapsida (Wiki) http://en.wikipedia.org/wiki/Therapsid "Therapsida is a group of the most advanced synapsids, and include the ancestors of mammals.[1] Many of the traits today seen as unique to mammals had their origin within early therapsids, including hair, lactation, and an erect posture." "The therapsids included the cynodonts, the group that gave rise to mammals in the Late Triassic around 225 million years ago." " Mammals, the only living therapsids, evolved in the Early Jurassic period." |