Amniotes split into the sauropsids (leading to birds and reptiles) and synapsids (leading to mammal-like reptiles). These small early mammals developed hair, homeothermy, and lactation (red lines).

Sauropsids good color vision (diurnal) ß keratin. The sauropsids split early into the parareptiles (leading to turtles) and the eureptiles (lizards, snakes, crocodilians, dinosaurs and birds).