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Science

Feathers On Reptiles Predating Dinosaurs 20

Posted by Hemos from the interesting-idea dept.
Weedhopper writes: "This is a news item in reference to an article in the latest issue of Science about a reptile with feathers that predates archeopteryx by 75 million years - predating most dinosaurs in fact. Though I am suspicious of any claim that a particular biological structure is too complex to have evolved twice, the case may be that birds may not have descended from dinosaurs as is commonly believed."
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Feathers on Reptiles Predating Dinosaurs More

Feathers on Reptiles Predating Dinosaurs

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  • Haiku (Score:1)

    by YASD ( 199639 )

    Fossil lizards? No!
    Scientist named Terry Jones
    Should study pythons!

    ------
  • story is bogus 4 thousand years old earth is The Bible says so
  • (Damn formatting, forgot to preview) Try again

    story is bogus
    4 thousand years old earth is
    The Bible says so


  • I do not agree
    With your views or with your math
    Your figures are off

    Two thousand A.D.
    Plus four thousand four B.C.
    Makes six thousand four

    ------

  • I still hope that, somehow, birds are descended from dinosaurs, largely because there's a pleasure in looking at ducklings on the salt marsh and saying "Baby dinosaurs!"

    <p>Feathers might have evolved twice, and I definitely want more data: did this creature have a breastbone? Can we run the line of descent from <i>Longisquama</i> to <i>Archeopteryx</i> through the dinosaur kin, and keep the seagulls flying at the end of the dinosaur exhibit at the Museum of Natural History?
  • Sorry I was wrong

    My numbers were very off

    Burn me at the stake

  • Although this discovery does seem to imply that birds would not have descended from dinosaurs, it does not eliminate the possibility of dinosaurs and birds having evolved from a common ancestory.

    Finding more evidence of a bird/reptile crossover such as this one would actually seem to strengthen the possibility that birds and dinosaurs have common ancestry.

    Unfortunately, that still doesn't explain the whole disappearance bit...

  • Just because this scientist thinks feathers are too complicated to evolve twice doesn't mean they didn't. Something as complicated as an eye has independently evolved in both vertebrates and cephalopods, there is no common ancestor to the 2 that had eyes. Cephalopod eyes might not be too impressive in slugs but an octopus has a very advanced eye quite similar to vertebrates. What is being described here is a trait from an ancestor of dinosaurs which is also a trait that has been ascribed to a descendent of dinosaurs. A recessive trait from an ancestor manifest in a descendent does not seem exactly impossible to me. There just doesn't seem to be anywhere near enough evidence yet to say that birds definitely are or aren't descended from dinosaurs, there just seems to be enough data to prove that feathers have been around a long time.
  • From what I read (just went to the school library to read the orig article) yes, it did have a breastbone and a "wishbone". But then again, as with all fossils, the function of any structure is open to interpretation.

    Its really open to interpretation on whether or not it had feathers at all.

  • My first thought when reading this article was the example of the eye as complex parallel structural evolution as well, but on second thought, that might not be a good analogy.

    There are better analogies to refute the featherlike structures too complex story. Not every "attempt" at evolution results in a successful product. For example, certain types of ferns "attempted" to develop seeds long before the modern parent of seed bearing plants did. For some reason or another, this family of ferns became extinct and nothing, evolutionarily, came of the seed like structures. Maybe this reptile attempted to develop feathers from scales but became extinct for whatever reason before it got the chance propogate itself.

    I think this is more plausible than a recessive gene being carried through 75 million years of development before manifesting itself in archeopteryx or whatever.

  • Re:feathers on reptiles predating dinosaurs (Score:3)

    by Black Parrot ( 19622 ) on Sunday June 25, 2000 @03:35AM (#980244)
    > Its really open to interpretation on whether or not it had feathers at all.

    Some scientists are scoffing at the idea. See e.g. the report at ABC News [go.com] -
    "Those are not feathers," said Chris Brochu, a paleontologist at the Field Museum of Natural History in Chicago. "None of the evidence they cite are preserved well enough to be convincing."

    Hans-Dieter Sues, a paleontologist at the Royal Ontario Museum in Toronto, Canada, says he studied the Longisquama fossil in his laboratory for months two years ago and he is sure the mysterious appendages are scales, not feathers.
    "The structures are solid and they have overlap with adjoining scales. They're definitely not feathers," he says. "These scientists are trying to show that birds may not have evolved from dinosaurs - that's clearly their agenda."
    Of course, both sides of an argument can have an agenda. I think it will take several months for a basic consensus to shake out, and of course the basic dinosaur -&gt bird question was already controversial before this, and will likely remain so.

    One claim by one of the dinosaur != bird crowd really annoys me, though -
    Jones says the sequence of bird-like dinosaurs appearing after the earliest known bird has never made sense to him. "It's like saying your grandmother was born after you died," he says.
    No, it's more like apes appearing after the earliest known hominid.

    --
  • > No, it's more like apes appearing after the earliest known hominid.

    I should have said, "more like specific species of ape appearing after the earliest known hominid." I.e., not a big problem.

    --
  • yeah that does sound fairly likely. Most of what i know about inheritance comes from c++ and java (heh heh). I was just trying to think of a way to say why i thought the claim of finding a single specimen of a supposedly feathered reptile was pretty thin evidence to say anything about the true origin of birds. But you know, a scientist would never make any sort of unfounded claims about the amazing earth shattering highly fundable signifigance of their research, so i'm sure if i knew more about this fossil i'd be in complete agreement that birds aren't descended from dinosaurs.
  • It has been done before
    One man was nailed to a tree
    When he said be nice.
  • I've never seen cephalopod eyes on a gastropod. ;-)

    If anything, cephalopod eyes are of a superior design. The nerves leading away from the photoreceptors in cephalopod eyes stick out the back. In vertebrates, the nerves stick out the front, blocking some of the light, and they have go out the back of the retina, resulting in a blind spot.

    This difference helps underscore the fact that cephalopod eyes and vertebrate eyes evolved separately (much like bird wings, bat wings, pterosaur wings, and insect wings). Parallel evolution is seldom parallel in the finer details.
  • One claim by one of the dinosaur != bird crowd really annoys me, though -
    Jones says the sequence of bird-like dinosaurs appearing after the earliest known bird has never made sense to him. "It's like saying your grandmother was born after you died," he says
    (corrected) No- It's more like specific species of ape appearing after the earliest known hominid." I.e., not a big problem.
    It is a problem if that specific species is thought to have been a pre-hominid species. The bird-like reptiles are thought to have been predecessors to birds. That's what makes the timing problematic.
    --
  • There are plenty of examples of convergent evolution around (i.e. unrelated creatures displaying similar features).

    Wolves look very similar to thylacines (marsupial 'wolves'), yet are more closely related to Man. Good point about cephalopods and vertebrates independently evolving eyes -- box jellyfish have nicely developed eyes, too, I seem to remember.

    However... lots of things have rundimentary vision -- after all, it's just a development of sensory pits found on plenty of Cambrian animals (trilobites, for example). Similarly, the thylacine/wolf similarity occurred because both are running quadruped predators -- long limbs, big jaws, etc.

    Flight feathers are a different matter, however. There's no easy path of progression from scales to flight feathers -- down (or fur), yes; flight feathers, no. Indeed, the whole development of flight is a pretty suspicious business anyhow. Compared to flying, this eye business is a piece of cake...

    In conclusion, there were the beginnings of visual organs in most early creatures, and it is not unreasonable to assume that Coelentrates (jellies and anemones), vertebrates and cephalopods had a common ancestor capable of light/dark perception. Similarly, whether feathered flight evolved alongside the dinosauria or from it, it is likely only to have evolved once in its rudimentary form (i.e. to the point where it slows falling or assists jumping and hence provides selection pressure for flight).

    Hope that made sense. --L.

  • "Indeed, the whole development of flight is a pretty suspicious business anyhow."

    Yeah, but look how many times thats come up independently. Flight has developed in insects, mammals (bats), birds (obviously), and probably a few others i'm not aware of. I know there were winged dinosaurs, but i'm not sure if they were gliders or fliers.

    "there were the beginnings of visual organs in most early creatures, and it is not unreasonable to assume that Coelentrates (jellies and anemones), vertebrates and cephalopods had a common ancestor capable of light/dark perception"

    I'm by no means a student of biology, but i seem to recall that the fundamental difference between the evolution of cephalopod and vertebrate eyes is that the vertebrates evolved from nerve cells while the cephalopods evolved from skin cells (i might be wrong though). I'm pretty sure this would mean that they didn't have a common visual ancestor.
  • For what it's worth, I'm actually somewhat ambivalent on the birds as tiny therapods thesis. At this point, I think that it's quite plausible that the birds arose from saurians; no obviously non-saurean precursors to the birds have been found, and a number of homologous structure in the therapoda and the avians have been discovered.

    That doesn't mean that birds are baby dinosaurs, though. It's certainly reasonable to assume that the therapods and the birds share close a common ancestor, but it seems hardly likely that the birds actually are derived from any of the dinosaurs that we know and love. (I've always liked Steve Gould's comment on why dinosaurs are so popular: "They're big, they're mean...and they're dead.")
  • All this investigation and thought is based on the view that evolution is the only answer. What about... 1) Creation? 2) Creation followed by a development/evolution of creatures? 3) Something completely different? Remember Evolution if a Theory that is changing almost every day!

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