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Turtles: Shells evolved for digging, not protection?

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File:Eunotosaurus africanus.jpg
eunotosaurus, considered a proto-turtle/smokybjb

From Ed Yong at Atlantic:

Tyler Lyson from the Denver Museum of Nature and Science has devised a fascinating new idea about turtle origins. He thinks that their iconic shells evolved not for defense, but for digging. They anchored the powerful arm strokes needed to shift soil and sand. Before turtles became impregnable walking fortresses, they were professional burrowers.

For almost a century, biologists argued about how turtles got their shells—a debate almost as slow and plodding as the creatures themselves. Paleontologists mostly argued that the shells evolved from bony scales called osteoderms, which are also responsible for the armor of crocodiles, armadillos, and many dinosaurs. These scales simply expanded to fuse with the ribs and backbone, creating a solid covering. But developmental biologists disagreed. By studying modern turtle embryos, they deduced that the shell evolved from ribs, which broadened out and eventually united. More.

Maybe. An even bigger mystery is how turtles know enough to right each other. How would they have learned that?

See also: Not a Big Bang of turtles TOO? As well as birds and mammals

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2 Replies to “Turtles: Shells evolved for digging, not protection?

  1. 1
    bornagain77 says:

    No, No, No! Turtle shells did not evolve because of digging.

    Turtle shells were selected by natural selection because of cosmic turtles! 🙂

    per Querius:

    “The multiverse idea is exactly one of those examples, and is not fundamentally any different from the claim of a trans-dimensional cosmic tortoise laying eggs that become universes.”
    Intelligent Design blogger
    It’s turtles all the way down! 🙂
    gif – trans-dimensional cosmic tortoise
    The sarcasm continues:
    From now on in discussions of the origin of the Big Bang, I will insist that a better explanation is the cosmic turtle hypothesis—that a cosmic turtle, one among many, is the origin of the cosmic egg that started our universe.
    There are several reasons that the Cosmic Turtle (CT) hypothesis is superior to the multiverse alternative:
    (1) It disallows two or more Big Bangs from occurring in the same place and time
    (2) It disallows a Secondary Big Bang, SBB(tm), from occurring *within* our universe
    (3) It enables the integration of Darwin’s Theory of Evolution to be applied to the Cosmic Turtle
    (4) It promotes spiritual unity between Chinese, Indian, Native American, and scientific mythologies.
    And Terry Pratchett, of course.


  2. 2
    Robert Byers says:

    Turtle shells, after the fall, were for protection. if not how would this creature be protected?
    An evolutionist must provide protection and so must agree the shell ended for protection.
    its poor speculation to say it was for gigging. it only has digging problems because it had a shell and a body plan to move slowely because it had a shell of weight on its back.

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