Figure 5.9   Swimming forepaddles of a variety of reptiles (ad) and mammals (eg): (a) Archelon, a Cretaceous marine turtle; (b) Mixosaurus, a Triassic ichthyosaur; (c) Hydrothecrosaurus, a Cretaceous plesiosaur; (d) Plotosaurus, a Cretaceous mosasaur; (e) Dusisiren, a Miocene sea-cow; (f) Allodesmus, a Miocene seal; and (g) Globicephalus, a modern dolphin. The forelimbs are all homologous with each other, and with the wing of a bird and the arm of a human. However, as paddles, these are all analogs: each paddle shown here represents a separate evolution of the forelimb into a swimming structure.

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