http://www.facebook.com/ScienceReason ... Evolution (Part 3): Highway of Life (Episode 3): From Mammals To Primates --- Please SUBSCRIBE to Science & Reason: • http://www.youtube.com/Best0fScience • http://www.youtube.com/ScienceTV • http://www.youtube.com/FFreeThinker --- The earliest mammal-like reptiles, called pelycosaurs ruled the earth for about 40 million years, and gave rise to the therapsids...one step closer to mammals. Therapsids are the direct ancestor of mammals. But before we say good bye to reptiles, let's pause and look down their temporal highway. Their descendants include the crocodilians, the dinosaurs and the birds. Back to our own road, Mammals are directly ahead. It is now 220 million years ago and the cynodonts have arrived on the scene. They have nearly all the features of mammals. Most early mammals were small and shrew-like animals that fed on insects. It is likely that they had a constant body temperature, milk glands for their young, and the beginning of a neocortex region of the brain. But this is also the era of the first dinosaurs, so our ancestors will have to wait for their turn to rule. 125 million years ago, two new developments paralleled each other, marsupials and eutheria. The marsupials would give rise to kangaroos and their cousins, but our line lies with eutheria which have a placenta. The earliest eutheria resembled a small mouse. 90 million years ago, we part lines with the ancestors of elephants and manatees, 85 million years ago, so long to the predecessors of horses, dogs and cats 75 million years ago, we part ways with mice and rodents. Primates are directly ahead. It is 65 million years ago and the dinosaurs just died. And a small animal that looked like a cross between a squirrel and a monkey becomes the ancestor of all primates. After a few million years, Old World Monkeys are clearly recognizable and, they have had a good run ever since. 25 million years ago the first of the lesser apes appeared. .
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