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New important transitional fossil for bats

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  • New important transitional fossil for bats

    New transitional fossils provide a more complete picture of the evolution of bats.


    Originally posted by http://listverse.com/2013/02/05/10-significant-recent-evolutionary-discoveries/

    Discovery: Decades-old bat mystery finally solved by intriguing fossil

    Bats are the second largest order of mammals, accounting for a fifth of all mammalian species. They’re the only mammals to have developed full flight and can use echolocation to a level unmatched by any other land-dwelling creature. These archetypal traits have been the subject to a longstanding mystery within biology—which came first? (For the related question, it’s apparently the chicken).

    A pair of fossils discovered in Wyoming in 2003, part of a new species dubbed Onychonycteris finneyi, has many odd features. It has claws on all five fingers, compared to the one or two found on modern bats, possibly as an adaptation for climbing in the forest canopy. More importantly it has the capacity for flight without the ability to echo-locate, confirming flight came first. Joining the dozens and dozens of other transitional fossils completely invisible to creationists, the fifty-two million year old specimen ends decades of speculation amongst scientists.
    Glendower: I can call spirits from the vasty deep.
    Hotspur: Why, so can I, or so can any man;
    But will they come when you do call for them? Shakespeare’s Henry IV, Part 1, Act III:

    go with the flow the river knows . . .

    Frank

    I do not know, therefore everything is in pencil.

  • #2
    Originally posted by shunyadragon View Post
    New transitional fossils provide a more complete picture of the evolution of bats.
    Not exactly "new" since the discovery is over a decade old. Still Onychonycteris finneyi, which lived 52.5 mya (Eocene) is indeed a great example of a transitional.

    Onychonycteris had an underdeveloped coclea of the inner ear associated with the radar-like echolocation abilities in most modern bats. The part of the skull where the cochlea is located was found intact allowing researchers to examine it in detail.

    Not all bats possess the means to echolocate because some of them have diets consist of things like fruit. You just don’t have much need for echolocation when your “prey” is an unmoving piece of fruit dangling from a tree or bush[1]. But the morphology of the dentition demonstrates that Onychonycteris was insectivorous, like other bats from the Eocene and not a frugivore (fruit eater).

    Onychonycteris also reveals many characteristics that demonstrate its evolution from a arboreal (tree-dwelling) insectivore. For example, while all modern species of bat have at the most claws on only one or two digits Onychonycteris possessed claws on all five fingers and several of the earlier species that are now extinct still retained bumps at the ends of their other digits. This shows a transition from a creature with claws on the ends of all of its digits to what we see now, creatures that have lost most of the claws through time since it no longer has to scurry through the trees in search of a meal.

    Onychonycteris and other early bats demonstrate that bats have been losing its claws as they are no longer necessary and confer no advantage, and may have been a hinderance, after they abandoned their previous arboreal existence.

    But that's not all. There is more evidence for Onychonycteris' transitional nature from arboreal insectivore to a flying insectivore.

    The proportion of its limbs which is unique among bats is another indication. This differing limb ratio places Onychonycteris somewhere between other bats and climbing mammals such as gibbons and sloths. IOW, this limb proportion is intermediate between all other known bats and forelimb-dominated non-flying mammals

    http://web.archive.org/web/20100612045005/http://www.plantbio.uga.edu/~chris/batgraph.jpg

    This, along with its claws, demonstrates a previous arboreal existence and is exactly what we would expect from a species located near the base of chiropteran evolution.

    Onychonycteris also possessed a long tail, which is common among extinct bats but not in modern bats. Of the species that still have longer tails, none are as long as those seen on the extinct species. A long tail is generally useful though not necessary when you’re climbing trees but not so much when you've developed flight.

    One final note. Onychonycteris demonstrates that flight developed before echolocation (a question that had been vexing scientists for many decades), but it possessed stubby wings that suggests that it’s flight was a sort of combination flutter and glide which meant it couldn't fly as far or as fast as later bats. Yet it still flew, which kind of destroys any complaint about “what good is half a wing.”





    1. Although Rousettus (a.k.a "flying foxes" or dog-faced fruit bats) appear to have some limited ability of echolocation -- as do most mammals

    I'm always still in trouble again

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    • #3
      rogue6

      Agreed that it is not new, new as far as the fossils, but the completion of the research is relatively new. I consider everything since 2000 new. Thank you for the extra reference material.
      Glendower: I can call spirits from the vasty deep.
      Hotspur: Why, so can I, or so can any man;
      But will they come when you do call for them? Shakespeare’s Henry IV, Part 1, Act III:

      go with the flow the river knows . . .

      Frank

      I do not know, therefore everything is in pencil.

      Comment


      • #4
        Originally posted by rogue06 View Post
        Onychonycteris had an underdeveloped coclea of the inner ear associated with the radar-like echolocation abilities in most modern bats. The part of the skull where the cochlea is located was found intact allowing researchers to examine it in detail.

        Not all bats possess the means to echolocate because some of them have diets consist of things like fruit. You just don’t have much need for echolocation when your “prey” is an unmoving piece of fruit dangling from a tree or bush[1]. But the morphology of the dentition demonstrates that Onychonycteris was insectivorous, like other bats from the Eocene and not a frugivore (fruit eater).
        That fruit bats have no echolocation would seem to be to indicate echolocation came second. Or are they evolved from bats that did?
        My Blog: http://oncreationism.blogspot.co.uk/

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