amazing and cool shit, dinner time conversation, miscellaneous, drivel, tom being tom



Inevitably, I wonder about things of this nature… If we are to believe in Darwin and his theory of evolution, what is to be thought of the case of the teensy arms on the dinosaurs we’ve dug up? Were they in the process of growing longer? Or were they in a state of decline, somehow deemed perfunctory and useless and allowed to atrophy for some unknown reason…


One thought on “…dinosaurs…

  1. They are what is referred to as a vestigial trait, a left-over mostly or entirely useless part of a species’ anatomy. Almost all land animals have four limbs and five digits on each limb, so those who don’t must logically have once had them if the common ancestry model holds water, which allows for scientists to predict the existence of prehistoric ancestral forms of modern species that lack separate digits or four limbs with great success. Horses have four limbs with 1 digit (a hoof is a single big toenail), and the further back you go in the fossil record the more digits horse-like creatures have. Whales also have hands with five digits inside their fins, and some still have hip-bones and vestigial hind legs, because they evolved from four-legged land mammals. Birds have four limbs but they don’t have separate digits – darwin predicted that their ancestors must have had separate digits, and two years later this was found:

    And so on and so forth.

    If you want an example of an early limb like what evolved in fish to become an amphibious leg, here is a modern example in bony sharks (which have all of the basic bones in your arm):

    Feel free to ask any questions you might have.

    Nerd man away!

    Posted by agnophilo | May 3, 2014, 5:32 pm

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