BIOL359 Lecture Notes - Lecture 10: Cambrian Explosion, Basilosaurus
14 Apr 2016
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Whales were hypothesized that they are actually a branch on their own of mammals. The history was not known (looking for fossil record to confirm hypothesis) How whales have evolved is important because it mirrors our own life history. Basilosaurus whales have bones of a pelvis, a knee cap and toes that can be seen within the fossil record. So the real hypothesis is have whales evolved earlier or have they evolved later to other animals? . Since whales had legs at some point they must have secondarily lost it as it no longer conferred an advantage to them. Mammals (whales) swim differently than fish do , they are actually more similar to terrestrial mammals that move on land. Animals (tetrapods) with limbs lived in the water at first and then they lost their limbs. Tetropods did not have to evolve limbs they were originally aquatic creatures much before terrestrial animals have existed.
