Evidence that Archaeopteryx is transitional from dinosaurs to birds
(A reply to an article by Duane Gish of ICR)

Post of the Month: January 2008

by

Subject:    Re: Invulnerable logic [Was:Re: How Our Brains Ignore Unpleasant
Date:       16 Jan 2008
Message-ID: e2pno3ph6gq58bl0ki8l3o4f924fgtt1t8@4ax.com

On Mon, 14 Jan 2008 11:44:51 -0800 (PST), Evopeach <keaton1943@yahoo.com> wrote in <f6df216e-ebbc-4afe-9a21-3f428d08ec36@v46g2000hsv.googlegroups.com> :

> On Jan 14, 10:04 am, chris thompson <chris.linthompson@gmail.com> wrote:
>> On Jan 14, 9:16 am, Augray <augray@sympatico.ca> wrote:
>>
>> snip
>>
>>> It's too bad that you haven't demonstrated that, and never will be
>>> able to. Gravity happens, as does evolution. But if you want to
>>> embarrass yourself even more, go ahead and explain which basic tenets
>>> are contented, why, and how.
>>
>> "We are tenets of evolution!
>> We get discussed while you eat lunch!
>> The New Synthesis revolution
>> Made us all a happy bunch!"
>
> http://www.icr.org/article/321/

Why is Gish relying on a quote by Beddard that was 90 years old when Gish wrote this article? Why are you falling back on an article that's almost 20 years old? Needless to say, there have been a plethora of discoveries in the last 110 years.

The article claims that Archaeopteryx had perching feet, but this is now known to be false. The hallux (the toe on the foot of perching birds) was in an intermediate position in Archaeopteryx. (Middleton 2003; Mayr et al. 2005)

Gish states that the feathers of Archaeopteryx were the same as those of living birds, but seems unaware that this doesn't mean that they were used for powered flight. They would also be useful for gliding, which may have been all that Archaeopteryx was capable of (Senter 2006). It should be pointed out that the paper cited (Feduccia & Tordoff 1979) is concerned with the isolated fossil feather attributed to Archaeopteryx, but there is no consensus that the assignment is warranted (Wellnhofer 2004; Ostrom 1970; Benton & Gower 2002; Jensen 1981). Finally, Feduccia & Tordoff don't claim that Archaeopteryx could fly under its own power, but that it "was capable of at least gliding".

Gish also states that Archaeopteryx had "an especially robust furcula (wishbone)", but this may argue against it being an efficient flyer, since in at least some living birds, the wishbone acts as a spring, and that of Archaeopteryx was too robust to do so (Jenkins et al. 1988).

Writing that "...there was nothing in the anatomy of Archaeopteryx that would have prevented it being a powered flyer", Gish cites Olson and Feduccia (1979), but doesn't reveal that they point out that Archaeopteryx didn't have at least one feature (the positioning of the supracoracoideus tendon) used in powered flight by modern birds. And there are several *other* problems with the idea that Archaeopteryx flew like living birds:

- It lacked an alula (used to reduce wing turbulence during low speed flight) (Sanz et al. 1996).

- The metacarpal bones were not fused into a carpometacarpus, as in living birds.

- The ulnare (a carpal bone in the wrist, AKA the cuneiform) was not V-shaped. In living birds this helps keep the wing rigid during the downstroke, and preventing it from buckling (Vazquez 1992).

- In living birds, the position of the acrocoracohumeral ligament prevents dislocation of the shoulder during the upstroke. This is not the situation in Archaeopteryx, where the ligament was situated as it is in crocodiles (Baier et al. 2007).

- The shoulder joint was oriented in such a way so that the wing could not be raised above the horizontal position (Poore et al. 1997; Senter 2006).

- Archaeopteryx lacked an ossified sternum for the attachment of the flight muscles, and so would not have been a very powerful flyer (Wellnhofer & Tischlinger 2004).

Gish then states that "It has been asserted that Archaeopteryx shares 21 specialized characters with coelurosaurian dinosaurs", but only discusses eight characters in the text that follows. He cites Whetstone (1983) to support the claim that the skull of Archaeopteryx was "bird-like, not reptile-like", but ignores the non-avian features that Whetstone mentions.

Surprisingly, Gish also reveals that:

    Benton has stated that "details of the brain case and
    associated bones at the back of the skull seem to suggest that
    Archaeopteryx is not the ancestral bird, but an offshoot from the
    early avian stem."

In other words, the braincase is not like that of living birds, which isn't exactly an argument against its transitional nature. And stating that it's "an offshoot from the early avian stem" is a claim *based* on evolution. In addition, this claim was far from unanimous:

    It seems to me that there is nothing in the structure of those
    regions which I have particularly studied which debars
    _Archaeopteryx_ from the direct ancestry of modern birds.
    [Walker 1985]

    Obviously, it is highly improbable that _Archaeopteryx_ actually
    represents a "mainline" antecedant [sp] of modern birds, but
    there is no evidence to rule out that possibility. [Ostrom 1985]

Gish also cites Haubitz et al. (1988) as basis for the claim that the quadrate (a bone that articulates with the braincase and lower jaw) is double-headed as in living birds, but unfortunately for this claim, the CT scan that forms its basis is rather murky. Paul (2002:37) describes it as "hopelessly ambiguous", and writes that

    If these was a double-head that contacted the braincase, the
    doubling appears to have been a very incipient condition most
    similar to the condition found in some dino-avepectorans and
    some birds.

This too is not an argument against the transitional nature of Archaeopteryx.

Martin et al. (1980) is cited for the claim that the teeth of Archaeopteryx were unlike those of dinosaurs, but troodonts (a variety of dinosaur believed to be closely related to Archaeopteryx) have been found with teeth very similar (Norell et al. 2000).

Martin et al. is also referred to for the claim that the ankle bones of birds are not homologous with those of dinosaurs, but this has been shown to be incorrect (Paul 2002:202-203, 211-212; Zhou & Zhang 2002).

Alick Walker's paper on the orientation of the pubis is cited in support of the claim that it was bird-like, but more recent finds show that it was intermediate in orientation, just like Ostrom claimed (Elzanowski 2002; Paul 2002:55-56; Padian 2004). In addition, some dinosaurs have been found with an even more bird-like orientation than that of Archaeopteryx (Norell & Makovicky 1997).

Gish correctly states that Tarsitano and Hecht (1980) criticized Ostrom's hypothesis of the dinosaurian ancestry of birds, but that doesn't mean that they were right, or that they disagreed with the idea that Archaeopteryx was a transitional form. They instead claimed that birds were descended from a group of animals called thecodonts.

    Our contention is that the present data indicate that
    _Archaeopteryx_ is derived from the thecodont level, at a point
    between the _Lagosuchus_ and _Euparkeria_ levels of
    organization. [Tarsitano and Hecht 1980]

Once again, this is not an argument against the intermediate status of Archaeopteryx. But new discoveries have solidly demonstrated that birds are the descendents of theropod dinosaurs. For more detailed explanations, see Paul (2002) or Dingus & Rowe (1997).

Gish cites an account of the Archaeopteryx Conference, which took place in 1984, for the claim that the otic region of the skull of Archaeopteryx is similar to that of living birds, but a more recent study questions this claim:

    The otic region, as exposed in the London specimen, has been
    interpreted under an assumption that its configuration in the
    archaeopterygids is similar in detail to the modern neognathous
    birds, although the braincases of _Archaeopteryx_ and
    neornithines are otherwise dramatically different.
    [Elzanowski 2002]

Also, had Gish gone to the bother of looking up the actual paper, he'd have read this:

    The otic capsule details, as far as can be observed, correspond
    exactly to the expected, primitive pattern... [Walker 1985]

In other words, Archaeopteryx is a bird, but a primitive one. This is not an argument against the Urvogel being a transitional form.

We're now treated to the embryological claim that the wing of birds contain digits II, III and IV, while the hand of theropod dinosaurs is constructed from digits I, II, and III. Aside from the puzzling fact that Gish is trying to wield an argument based on evolutionary assumptions, few consider this to be a huge problem anymore. There is a known mechanism that allows "digit identity" to change (Dahn & Fallon 2000), and such changes in identity are seen in the wild (Wagner & Gauthier 1999).

Next, the evolution of feathers is up for "examination". After a simple explanation of how feathers grow, Gish refers to Regal's paper (1975) that proposes a scenario for the origin of feathers. Gish then states that

    Regal's paper simply adds another "Just-so" story to
    evolutionary scenarios, completely devoid of empirical support.

Did Gish read the paper he refers to? Regal gives several examples from living organisms in support of his position, and he conducted experiments to test his ideas. This is not "completely devoid of empirical support". Nevertheless, Regal's ideas have been superseded (Prum 1999), and fossils have been discovered that support an evolutionary origin for feathers (Schweitzer et al. 1999; Chen et al. 1998; Xu et al. 1999; Xu et al. 2001).

The "canard" of Protoavis is now brought up, but its discoverer, Sankar Chatterjee, doesn't see it as causing a problem for the intermediate nature of Archaeopteryx, and believes that his find is descended from dinosaurs (Chatterjee 1997). There is no reason that Archaeopteryx couldn't be a holdover from an earlier time. But at this point there is no consensus as to whether or not Protoavis is even a bird. For instance:

    Ostrom stresses, however, that the remains are very fragmentary,
    and while agreeing with Chatterjee's tentative classification
    says the case is not finally proven. [Beardsley 1986. This is the
    second part of Gish's reference 14]

Also:

    Gauthier, who has examined the actual _Protoavis_ specimens, says
    most of the bones are poorly preserved, making it extremely
    difficult to identify many of the features that important to
    Chatterjee's argument. "It's crushed, smooshed and in really
    terrible shape," he says. [Monastersky 1991]

And finally:

    The material has become a paleontological Rorschach test of one's
    training, theoretical bias, and predisposition.
    [Padian & Chiappe 1998]

Hoyle and company's claim that Archaeopteryx is a forgery is now trotted out. But a discovery of an Archaeopteryx specimen in 1988 should lay to rest any claims of forgeries. Prepared by an reputable museum,

    ...the feather impressions are not only distinct, but also pass
    under the bones of the wing. It would be nearly impossible to
    fake such an effect. [Shipman 1989]

The forgery claim is dealt with elsewhere in much more detail (See http://www.talkorigins.org/faqs/archaeopteryx/forgery.html ). But one has to wonder why even Gish would take it seriously, since he believes that Archaeopteryx is all bird. But this point it's obvious that he's just flinging mud, and hoping that some of it sticks.

Finally, Gish puts in a word for his book "Evolution: The Challenge of the Fossil Record" for more "discussion" of Archaeopteryx. These claims have been debunked in http://www.talkorigins.org/faqs/archaeopteryx/challenge.html

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>It's an extinct bird, nothing more,
>and not transitional between dinos and birds, period.

How would you know? You said that you'd "examine, reason, and not accept dogma", and then blindly accepted something written by someone with admitted religious motives. Obviously, you were lying yet again. It's too bad for you that Gish's claim crumble under examination.

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