Oct 09 2009

Archaeopteryx Bones Dinosaur-Like

Published by under Education
Comments: 5

archaeoI wrote a couple of weeks ago about a new bird-dinosaur link and the new oldest bird, Anchiornis huxleyi, which took the title away from one of the iconic fossils of evolution – Archaeopteryx. A new study just published gives us some new information about Archaeopteryx. It turns out the structure of its bones was more like a dinosaur’s than a bird’s.

This has led to some annoying headlines: ‘First Bird’ Not Very Bird-Like. The new study actually does not change our thinking about Archaeopteryx – it is a basal bird, so it has some primitive bird features, and some dinosaur features. Now we know its bones were more like a dinosaur – just like its teeth and tail. This is what we would expect from a transitional species like Archaeopteryx.

For background, Archaeopteryx lithographica was first discovered in 1861 – what is now called the London specimen. There are currently a total of 10 specimens plus one separate feather (many sources I found still give the outdated number of 8 specimens, but there have been a couple more recent finds). Pictured above is the Berlin specimen.

Archaeopteryx is perhaps one of the most famous fossil species because of its timing – right around the time of the publication of Darwin’s On the Origin of Species. Darwin’s Bulldog, T.H. Huxley, was among the first to speculate that perhaps birds evolved from dinosaurs. So the discovery of Archaeopteryx was timely confirmation of both evolution and the dino-to-bird hypothesis.

It is one of the most spectacular transitional species we have. It has primitive avian features: feathers, an opposable hallux, and a fercula (wishbone). It also seems that Archaeopteryx was able to fly. But simultaneously it has many reptilian features: it lacks a bill or beak, free rather than fused truncal vertebrae, elongated cerebral hemispheres, a long bony tail, teeth, rear-attaching skull (birds’ attach from below), abdominal ribs, and claws on three unfused digits.

It also lacked some modern adaptations to flight, such as a triosseal canal, a specialized structure that enables modern birds to perform a wing flip maneuver that helps them take off from a standing start on the ground.

Generally speaking, Archaeopteryx retains many more features of theropod dinosaurs than it has modern avian features, and it lacks sophisticated adaptations of flight. It was more a flying feathered dinosaur than a bird. Again – a compelling transitional species.

This new study, therefore, fits right in with our current view of Archaeopteryx (which doesn’t make for splashy headlines). Looking at the bones of Archaeopteryx:

The bones from these early birds looked similar to those of same-sized dinosaurs, as they were dense with small blood vessels and bone cells that were flattened and parallel.

This implies that Archaeopteryx was slow growing, like dinosaurs, rather than fast growing like birds, which we would then infer was a later adaptation in the line that led to modern birds.

The stunning evidence for the evolution of birds from dinosaurs does not stop evolution deniers, who are immune to evidence. Answers in Genesis has an article on Archaeopteryx, and they get just about everything wrong. They grossly misrepresent the factual evidence (claiming, for example, that there is little evidence for feathered dinosaurs) and resort to their go-to logical fallacies (Archaeopteryx is just another kind of creature that God made). I will leave it to my interested readers to take it apart further – it’s a good primer on the logical fallacies of denial.

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5 responses so far

5 Responses to “Archaeopteryx Bones Dinosaur-Like”

  1. Calli Arcaleon 09 Oct 2009 at 2:55 pm

    I only glanced at the Creationist article briefly (didn’t want my brain to atrophy), but I noticed an interesting claim in their argument that dinosaurs were actually cold-blooded and therefore not related to birds. Their piece de resistance of evidence is a fossil theropod which apparently (according to them; I didn’t check to see if they’re citing it accurately and don’t really trust them to do so) shows evidence of lungs with a diaphragm. Crocodiles, they note, have diaphragms. Birds do not.

    Excuse me? *Humans* have diaphragms. Would they argue, then, that humans are cold-blooded? This is about the stupidest argument I could see them make. Obviously some animals with (in their minds) “lizard-like” lungs are not, in fact, cold-blooded.

    A better argument would have been that different lung structures suggested they were unrelated, rather than suggesting that it makes dinos cold-blooded. Of course, that would’ve meant suggesting that dinosaurs are related to crocodiles, which goes against the dino-bird link but is still very much an evolutionary argument. ;-)

    Much of the rest appears to resolve to “I don’t get it, therefore it’s wrong”. Which, unfortunately, is fairly common among those convinced of their own brilliance. It also betrays a level of self-confidence that, in my opinion, borders on idolatry. They cannot conceive of not being able to understand something which is true. Therefore, they are putting themselves on a level with God by suggesting themselves to be infallable. One would think that their professed religion would warn them against this, especially since they so often accuse scientists of hubris.

  2. SomaliAutismCommunityon 09 Oct 2009 at 9:59 pm

    This is intresting article and Calli Arcaleon your argument in intresting too.

  3. [...] older news, Archaeopteryx is still a transitional fossil, and a very cool one [...]

  4. God Fearing Atheiston 11 Oct 2009 at 10:25 am

    Steve,

    You write that Archaeopteryx had “an opposable hallux,” but this is unlikely. As part of his dissertation, Kevin Middleton found that that the degree of reversion relative to the cranially facing digits is a function of two things: the orientation of the metatarsal 1 fossa on the tarsometatarsus and the torsion of the hallucal metatarsal (more twist, more reversion). The reason, he thinks, is that because flexor tendons run down the back of the tarsometatarsus from muscles anchored above, simply moving the first metatarsal around to the back would get in the way and mess everything up. If you twist the bone, there is no disruption.

    Middleton’s investigation of the specimens revealed that Archaeopteryx has no torsion. This was corroborated in the Theropolis specimen (Mayr et al. 2007), where the hallux was found attached to the distal quarter of tarsometatarsus.

  5. Watcheron 11 Oct 2009 at 10:37 pm

    Calli, you’re missing their point. Since the holy spirit is in them, they can say no wrong. Everything they believe is given to them by the holy spirit since the holy spirit can only tell the truth … Basically, since they’re filled with the holy spirit, who speaks through them since they have faith, everything they say is the truth, and everything anyone else says is false …

    Damn, almost made it through with a straight face :)

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