Saturday, June 30, 2007

The Reptile to Mammal link

Noteworthy items: The period is from the Permian to the Triassic. Here are some of the evolutionary marks from fully reptile to mamalian-reptiles.

1. The switch in teeth appearance. From peg like to differentiated teeth of mammals - incisors, molars, canines.
2. The switch in jaws appearance. From 5 bones to 1 bone the dentary. In the reptilian past and present, the jaw joint lies between the articular bone at the back of the lower jaw, and the quadrate bone in the skull. But in mamals In mammals the jaw joint is between the dentary and the squamosal element of the skull.
3. The switch in the middle ear. In reptiles, as in amphibians and fishes, there is a single hearing bone, the stapes. But in mammals, including humans, have three ear bones, hammer, anvil, and stirrup or stapes.

OK. So here it is folks. More evidence that evolution can be traced and predicted. It is not an empty scientific proposition.

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