MadSci Network: Evolution |
You are quite right in saying that the bat's wing is homologous to other structures like the human forearm and hand, and the whale's flipper. Bats present some difficulty in the study of their evolution, however due to the understandable lack of fossil preservation. Being a flying mammal, with very delicate structures, it is exceedingly rare to find a bat fossil that can tell us anything, as the thin soft membranes and bones do not survive until fossilization, which requires a quick burial - something a flying animal rarely has. Nevertheless, in the abscence of much solid evidence, we can still put forward theories, and at the moment, there are two theories as to how the bats' wings and flight could have evolved. The arborial theory says that bats probably evolved as gliding animals first, living in the trees and having skin flaps much like those of flying squirrels. Extending and thinning the skin, along with lightening and exteding the bones, would give ever more control over their leaping, which eventually became true flight. The cursorial theory says that bats could have evolved the same structures by way of running and leaping off the ground, perhaps into an updraft or off a cliff. I favor the arborial theory, as we have evidence of a niche that can be filled by such gliding animals leaping from tree to tree, and we do not see any mammalian gliders taking a running leap. But there may be other evidence that supports either theory, you will have to consult a zoological library to be certain. Good luck, and thank you for using the Mad Scientist Network!
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