As a distraction (or should that be ‘procrastination’?) from what’s currently filling up my diary (ie processing student enrolments), I’ve decided to look at another of those ‘science’ statements from the school documents I linked to in my last post. “What about the archeopteryx?” they ask. Well, what about it? This, from their webpage:
The archeopteryx is an extinct, unusual bird. Two fairly complete skeletons have been found in Europe.
Correct as far as it goes – but there are actually eleven specimens, including an isolated feather also attributed to Archaeopteryx. Interestingly, one of those specimens was originally identified as the small maniraptorian dinosaur Compsognathus on the basis of its skeletal remains (its feathers were poorly preserved & not noticed by the original excavator).
Unlike “modern birds” it had teeth set in sockets, claws on the ends of its wings (although the hoatzin in South America still does today), and a stronger than usual pelvic bone. However it also had muscle attachments (skeletons can reveal a lot) consistent with strong flying (like a raptor today), feathers, and strong talons.
Archaeopteryx also had a long, bony tail; no large, projecting keel associated with the sternum (& a keel is the place where birds’ big flight muscles are attached); and little fusion of bones in the spine & limb girdles. It didn’t have the horny (keratinised) bill that you see in birds. And that pelvic bone (girdle?) may have been strong but its morphology is like that of dromeosaurs, not birds. The point at which the head attaches to the spine, and the form of the cervical vertebrae, is also reptilian, not avian. Yes, skeletons can reveal a lot, and what this (partial) list shows is that, while Archaeopteryx had a number of features we normally associate with birds – most notably, its feathers – it also possessed a large number of features that link it to reptiles and, more particularly, to theropod dinosaurs. It is, in other words, an example of a transitional form.
As for the strong flight that our website’s authors are arguing for – the relatively flat sternum doesn’t support that. Similarly, modern birds have what are known as uncinate processes on their ribs, which help strengthen the ribcage against the compression stresses generated by flight. Archeopteryx didn’t have those, either…
Modern biology textbooks picture the archaeopteryx as an awkward flier, or even glider, which could run and climb well, as a transitional form between reptiles and birds. This is probably the most famous fossil in the world other than some “ape-men”.
Ooops. I guess they don’t agree with the idea of human evolution either. Anyway, Archeopteryx probably didn’t climb trees on a regular basis: if it did, its wing claws would be worn down – but the fossils’ claws are sharp & unworn. So, when it flew, it would have taken off from the ground.
Firstly, evolution is very short of transitional forms so the most has to be made out of whatever can be found.
Secondly, we know by the muscle attachments and feathers that archaeopteryx was a strong flier, making some pictures in biology texts intentionally deceptive.
See my previous comments. The structure of the primary feathers on Archaeopteryx‘s wing tell us it flew, but the evidence from sternum & ribs suggest that it was not a strong flier – something that Pat Shipman discusses at some length in her book “Taking Wing”. So no intentional deception there – but perhaps a failure to look seriously at the available evidence by our authors.
A true transitional form must have structures that are part way between feathers and scales, and forelimbs that are partway between legs and wings. Everything on the archaeopteryx is fully developed. Like the platypus it is an unusual collection of fully developed traits.
Nice straw man argument there! This is not how biologists describe transitional forms.
Incidentally, modern birds have been found in the same and lower levels than archaeopteryx.
Bzzzt! Wrong again. The early birds contemporaneous to Archaeopteryx were not truly “modern”, although you could argue that they were more bird-like than Archaeopteryx. (I wonder if they may be referring to Protoavis?)
Some mammals have teeth and some don’t. Some fish have teeth and some don’t. We don’t see any issue with a fossil bird having teeth. And again, if fossil birds had teeth and today’s don’t, it is a loss, not a gain of genetic information.
Well, no – because some rather cool experimental work has shown that hens still have the genes controlling tooth development, so there has been no ‘loss’ of information. Sorry, guys, if you are claiming to teach science, then it would be a good idea to actually check out the available information rather than making these unsupported statements. In other words, your concluding statements don’t match the evidence & are wrong, wrong, wrong – and betray a wilful misunderstanding of evolution, as well:
Artists have creatively imagined what a true transitional form between reptiles and birds may have looked like. Such “creatures”, if they ever existed, wouldn’t be able to either fly or climb or run properly to escape predators or catch prey. Natural selection would have removed them. (Natural selection is on our side.) The unwelcome position of the evolutionist is that every step, and every small change, must be useful to the carrier to avoid being selected against.
Sigh. Spot the straw men? Not to mention the misunderstandings about natural selection & how it operates…
Update: the February 2011 National Geographic stated that the archaeopteryx, whose well developed feathers causes [sic] a problem for dino to bird dating, was probably such a good flier, that it could probably take off from the ground [emphasis in the original]. Well done National Geographic! We hope that the corrections flow down to the textbooks, but this may be hoping too much.
What is really hoping too much, I suspect, is that the authors of this school’s site take the time to look carefully at the available evidence & see where that leads them. (National Geographic’s represenation of a land-based takeoff is right in line with what most palaeontologists have said for years.) In this particular case they could make a start with reading Shipman’s book for an introduction to the science that’s written for the lay reader.
Pat Shipman (1988) Taking wing: Archaeopteryx and the evolution of bird flight. Touchstone. ISBN 0-684-81131-6