Dinosaurs, Birds, Feathers, and Conodonts (Oh, My!)

Most of the readers of this blog are intelligent, interested, scientifically literate individuals, but I'm guessing that at least a few of you aren't familiar with one of the nouns in the title. Those of you who do know what a conodont is are probably wondering what it has to do with the others. If you bear with me for a little bit, the connection will be clear shortly. It has to do with fossils, fossilization, and the latest spectacular misunderstanding of those two things at Uncommon Descent.

Conodonts are (or, rather, were) an interesting group of animals. They were around from late in the Cambrian period until the end of the Triassic, and were quite common during most of the period. They're not well known to most people outside of geology because the vast bulk of the evidence we have for them consists of very tiny tooth-like fossils. Most are only a millimeter or two in size, and are very hard to see without a microscope. They've received a lot of attention from paleontologists over the years because they're very useful little critters, particularly for geologists who work in the oil and gas industry. The thing is, for a long time nobody knew just what sort of critters they actually were.

The Russian paleontologist who first described conodonts, C. H. Pander, believed that they were the teeth that were left behind by some sort of primitive fish. That hypothesis was soon joined by many others. In 1988, Sweet noted that, "about the only major invertebrate phyla that have not been suggested as the parental group for the conodonts are the Archaeocyathida ... the Porifera, Bryozoa, Echinodermata, and Hemichordata." Scientists weren't sure what conodonts were because all that they had to work with were the little teeth-like microfossils. That was the only feature that the animals had that fossilized readily, and from 1856 until 1983 the phosphatic elements were all that scientists had to go by.

The first fossil of a whole conodont animal was found in 1983. By 1988, when Sweet wrote his monograph, more than five thousand species of conodont had been described, and five individual conodonts had been found with reasonable soft-body preservation. It wasn't until 2000 - nearly 200 years after Pander first described conodonts - that enough data had been gathered for scientists to do a formal analysis of conodonts and conclude that Pander's initial classification was probably close to correct. The conodont elements aren't actually teeth in the strict sense, but cladistic analysis suggests that the conodonts were, "the most plesiomorphic member of the total group Gnathostomata" (Donoghue et al., 2000). In English, that means they were, in fact, primitive fish.

In many ways, the question of what conodonts were is similar to questions about whether dinosaurs had feathers. In both cases, there was a long period of time when there was a limited amount of circumstantial evidence and a limitless amount of speculation based on the evidence that was available. Feathers, like other soft materials, don't preserve very well. There's been speculation almost since Jurassic Park hit theaters about whether the movie's depiction of Velociraptor as an animal with scales was correct, or if the animal should have been shown with feathers instead. It wasn't until last week that anyone was able to present physical evidence for feathers in that species.

When it comes to things like muscle, internal organs, and soft body coverings, the fossil record is very, very limited. We have few fossils that preserve any of those things not because they didn't exist, but simply because they don't preserve well. Skin and muscle decay quickly, while bone tends to hang around for a lot longer. This means that we need to be very careful about how we interpret fossil evidence for the things that preserve poorly - particularly when it comes to timelines.

That's something that they don't seem to have figured out at Uncommon Descent. In a post there today, the author (idnet.com.au) examines the fossil record for feathers, as reported in a seven-year-old Current Opinions in Genetics and Development paper. The UD author, after examining this record, concludes:

This is a clear example where the predicted fossil evidence is actually reversed. Protarchaeopteryx arose 9my after Archeopteryx. Protofeathers arose 25my after flight feathers. This is like finding a fossil rabbit in pre cambrian strata. The conclusion is of course, Darwinian evolution is obviously true.

(all emphasis in original)

The UD author clearly didn't grasp (or read) what the authors of the paper had to say about the timeline, which is actually funny, because he quoted part of it in the UD post:

One may wonder why the more primitive feathers seem to appear later than complex ones in the fossil record. Well preserved fossils, particularly those of the integument, are very rare and the absence of such examples does not mean that they did not exist. Furthermore, different levels of integument complexity probably co-existed, reflecting inhabitance of different niches. Such diversity still exists today.

(Italicized material was not quoted at UD, for some strange reason.)

It's possible that the UD author didn't grasp this because the language of the scientific paper was too obtuse, so let me try to explain this in simpler terms.

It's not safe to assume that the oldest fossil protofeathers we know of are the same age as the first protofeathers to appear on an animal. We don't have fossil evidence that they showed up earlier than that, but given how rare it is for feathers or skin to be preserved, that's not exactly a surprise. The oldest preserved conodont "teeth" come from the Cambrian, but the oldest preserved soft-body conodont fossil that I know of comes from the Ordovician (Gabbott et al., 1995). Dinosaurs first appear in the fossil record about 230 million years ago, but the only preserved dinosaur heart that I know about is only 66 million years old. It's reasonably safe to assume that dinosaurs had hearts during the Jurassic, and that conodonts had bodies during the Cambrian. It's not safe to assume that protofeathers weren't around before the first fossilized protofeather showed up.

References:

Donoghue, P. C. J., Forey, P. L., & Aldridge, R. J. 2000. Conodont Affinity and Chordate Phylogeny. Biological Reviews. Vol 75. Pp 191-251.

Gabbott, S. E., Aldridge, R. J., & Theron, J. N. 1995. A Giant Conodont With Preserved Muscle Tissue From the Upper Ordovician of South Africa. Nature. Vol 374. Pp 800-803

Sweet, W. C. 1988. The Conodonta: Morphology, Taxonomy, Paleoecology, and Evolutionary History of a Long-Extince Animal Phylum. Oxford. Clarendon Press. 212 p.

24 responses so far

  • GvlGeologist, FCD says:

    It's possible that the UD author didn't grasp this because the language of the scientific paper was too obtuse, so let me try to explain this in simpler terms.

    You're much more charitable than I am. I would interpret that to be typical ID quote-mining, leaving out the part that really shows that they deliberately misinterpreted the implications of the research.
    A great article. I looked up the link you have at "It wasn't until last week that anyone was able to present physical evidence for feathers in that species." My only concern is that it seems that the bumps used to interpret the presence of feathers on the ulna are much smaller than the example from the turkey vulture, and this suggests that we need to be careful in the interpetation.

  • wright says:

    Fascinating. And a calm, clear reply to another oft-repeated creationist "argument".
    Indeed, the fossil record as we currently know it backs the ToE up very well. And we need to keep in mind that this represents a tiny fraction of the fossils that undoubtly exist, which in turn are an even smaller fraction of past life forms.

  • JakeS says:

    "One may wonder why the more primitive feathers seem to appear later than complex ones in the fossil record."
    More primitive feathers could be preserved in some lineages long after evoloving to more complex forms in others.

  • Alex, FCD says:

    This is like finding a fossil rabbit in pre cambrian strata.

    It's more like finding a fossil rabbit slightly deeper in holocene strata than you expected. Nice try, though.

  • Ken Mareld says:

    Yes, you are being charitable. The article was not obtuse, the guy at UD simply ignored what he didn't like.

  • arachnophilia says:

    the dinosaur featured in jurassic park is most assuredly not a velociraptor mongoliensis, anyways. much too large, and the head's all wrong.

  • Stuart Weinstein says:

    Mike,
    I could be wrong, but perhaps instead of "obtuse" you may mean "esoteric". Although I didn't read the paper.
    Stuart

  • Stephen says:

    The word that was lurking at Mike's fingertips was probably "abstruse".

  • hoary puccoon says:

    Oh, the shame! Mike said obtuse when he meant abstruce! There should be a post coming up on Uncommon Descent any moment, now; "Science Blogger's Analysis Flawed!"

  • hoary puccoon says:

    The horror! I misspelled abstruse! No wonder scientists have no credibility! 😉

  • Anonymous says:

    Oy vey, I have used obtuse in the same manner as Mike. Probably because I have read someone misusing it.
    "Abstruse", eh? Now I have to repeat it somewhere to make it stick. Oh, wait, I just did that.

  • Anonymous says:

    Oy vey, I have used obtuse in the same manner as Mike. Probably because I have read someone misusing it.
    "Abstruse", eh? Now I have to repeat it somewhere to make it stick. Oh, wait, I just did that.

  • Jason S. says:

    Creationists often have difficulty not seeing evolution as a distinct linear chain. You can think of this as a variation of the classic, "If humans evolved from apes, why are there still apes?" reasoning. If Protarchaeopteryx-like species gave rise to Archeopteryx-like species, then why would there be Protarchaeopteryx around? Nay, "Protarchaeopteryx arose 9my after Archeopteryx."

  • Chiefley says:

    "This is a clear example where the predicted fossil evidence is actually reversed. Protarchaeopteryx arose 9my after Archeopteryx. Protofeathers arose 25my after flight feathers. This is like finding a fossil rabbit in pre cambrian strata. The conclusion is of course, Darwinian evolution is obviously true."
    In other words, if most Americans came from Europe, why are there stil Europeans?

  • TGos says:

    "In other words, if most Americans came from Europe, why are there stil Europeans?"
    Furthermore, how can a fossil of an American (found in a graveyard) be OLDER than another one found in Europe? Huh, smart guy?

  • John Duffy aka Medokh says:

    Obtuse? Abstruse?
    I had rather thought .

  • John Duffy aka Medokh says:

    Obtuse? Abstruse?
    I had rather thought obscure.

  • hoary puccoon says:

    Well, the fight seems to be between abstruse and obscure. And the IDers claim Darwinists can't tolerate controversy!

  • David vun Kannon says:

    Ok, are you going to fill us in on why the oil and gas industry loves conodonts, or just leave us hanging? 🙂

  • GvlGeologist says:

    Conodonts are useful in the oil and gas industry for two reasons. First, as many microfossils are, they are useful for stratigraphy - telling how old the rocks are. Secondly (and I'm remembering from 30 year old undergrad studies) I recall that they change color with increasing temperature. This is useful because you can tell if enough heating has occurred to cook organic material into petroleum first, then gas.

  • David Marjanović says:

    My only concern is that it seems that the bumps used to interpret the presence of feathers on the ulna are much smaller than the example from the turkey vulture, and this suggests that we need to be careful in the interpetation.

    Many birds have such small quill knobs; there's a very wide range in quill knob size in birds today. Some even lack them altogether, even though they fly. I suppose Turner et al. chose a turkey vulture because it has nicely visible quill knobs and because they happened to have one handy.
    On another note, obtuse means "blunt" (the opposite of a sharp intellect). Abstruse means "crazily absurd". Obscure means "hidden".

  • hoary puccoon says:

    Abstruse means "crazily absurd"? Where did you get that definition? The Oxford English Dictionary says it means obscure or recondite. This is obviously VITAL to the ENTIRE FUTURE of EVOLUTIONARY "THEORY" !!!!
    So let's get it right (or argue some more, if that would be more fun.)

  • David Marjanović says:

    Where did you get that definition?

    From its usage in German. I think I've encountered it that way in English, too.
    There's not that much difference; it's "dug up from some obscure abyss" either way.