How do you evolve a BAT?

Hi, RAZD.I'm not a bat man ( ), but the evolution of flight is always an interesting topic, so I'll give it a little whirl. I'm going to go out on a limb and say upside-down hanging evolved after flight. Since bats don't have the bipedal posture to stand upright like birds, they adapted to hang. Spiders routinely hang upside from their webs, which (at least in the spiders) doesn’t require muscle tension (because they hang by their hook-like claws, I think). With the bat, it obviously requires some sort of tension in the digits, but I don’t know much about that. I don’t think I have a good answer for this one. Bats do still have an unwebbed thumb, but I think that’s mostly used for climbing (probably testifying to bat ecology before flight, I would think). I can personally only envision the process happening in a "trees-down" direction, simply because it's ecologically the more parsimonious. Further, I think webbing is just a natural artifact of vertebrate skin stretched over bone, so I would guess that webbing could evolve in practically any vertebrate lineage that has retained long digits.Have you heard of a colugo? They are related to primates, and have the most extensive patagium of all gliding mammals (here is a really cool picture of one in flight). Their fingers are also webbed, like bats’.I think bats could have started out like a colugo, and gradually extended all or some of their fingers to improve their flight control, and eventually settled on keeping only the thumb for climbing and using the rest for flying, especially after they learned how to catch prey on the wing. I'm going to reject WAIR in the bat’s case, simply because the bipedally cursorial adaptations of theropod dinosaurs and birds don't seem to be present in either shrews or bats.The flapping mechanism in bats isn’t all that spectacular or complex: it’s just an enlargement of the muscles and bone structures that all mammals have, except that the shoulder blades are more free to move (or something like that; it’s been awhile since I took Comparative Physiology). I could see that adaptation coming from a gliding mammal just flailing to reach a couple inches further.Edited by Bluejay, : Repeated line.Edited by Bluejay, : Fix dBCode error from a frickin' long time ago.

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-Bluejay/Mantis/ThylacosmilusDarwin loves you.

Hi, RAZD. Awesome: I didn't even think about that. ToL puts bats and colugos as sister groups, so you could be right about the "hanging-first" model.But, much of the genetic data is returning the four-way Eutherian split (Xenarthra, Laurasiatheria, Afrotheria, Euarchontoglires), which puts bats in Laurasiatheira as the relatives of Perissodactyla and the Carnivora/Pholidota, and colugos and sister to Primates within the Euarchontoglires. If this split is correct, your hanging observation may not be relevant.Edited by Bluejay, : Very bad wording.

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-Bluejay/Mantis/ThylacosmilusDarwin loves you.

Hi, RAZD. Okay, so you weren't arguing common ancestry: you were just arguing for proof-of-concept. I gotcha.

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-Bluejay/Mantis/ThylacosmilusDarwin loves you.