My previous post "The origin of snakes" was post #100 on why I hate theropods.

Since post #100 was on the vortex that is snake origins, then post #101 should be on the vortex that is turtle origins. :)

I usually try to avoid turtles. I've covered them once before on this blog [link]. The catch in covering that is that I was commenting on how a creationist blog was quote mining news articles on Odontochelys, a transitional turtle from China.

Now once again, Michael of "New Discoveries & Comments About Creationism" is providing us with more uninformed commentary regarding turtle origins. Read: "Morphology: The Quest To Explain A Turtle's Shell"

Michael oversimplifies and goofs on the differences between emergentist and transformationist views:
"Now transformationists believes there is a “morphological evolution as a result of natural selection working on variation.” On the other hand, emergentists, believe in looking for developmental stages of turtles to look for clues about their evolutionary history."

Michael is just basically paraphrasing Rieppel on tidbits to provide the necessary launching ground for his 'attack'.

When it came to explain Odontochelys researchers took the “emergentists” approach…"

"Not surprisingly, the researchers in this paper already were focused on Odontochelys being a ‘missing link’ rather than a specialized form. More glory in ‘missing links’ than specialized forms. They on with their explanation which turns out to be a very confusing statement"

First, Michael presumes the authors accepted a de novo origin of the shell a priori, which may not really matter given their developmental observations seems to strongly favor it. Maybe Odontochelys is a specialized aquatic proto-turtle that has little to do directly with the origins of the rest of the group, but that isn't what the developmental evidence suggests.

Second, I do not see anything confusing about the statement that Michael quotes (see his blog--but it's basically the last paragraph of Nagashima et al.'s paper), and it is not explaining away the 'biogenetic law while using it to explain turtle evolution'. 1. They are not claiming that turtle embryonic development complete recapitulates the evolutionary history of turtles. 2. They are claiming that their observations of developing turtle embyros shows that the carapace is formed from intramembranous bone around the ribs and vertebrae, rather than fusion of separate bones with each other and the underlying ribs as argued by the composite or transformationist viewpoint. 3. This claim seems to suggest that developmental observations agree with the "de novo" or emergentist hypothesis of the origins of the shell in an evolutionary context, to which Odontochelys also seems to support.

Perhaps if Michael had digested the paper in its entirety he would not have been confused. But from there, he spouts off the usual creationist spiel regarding Haeckel and 'ontogeny recapitulates phylogeny'. In response to that, I'll simply point to Talk Origin's Index to Creationist Claims--see "Haeckel falsified his embryo pictures" and "Recapitulation theory is not supported".

I've kept my comments relatively muted here because comments by 'Olorin' on Michael's blog have already taken him to task. See here, but in case Michael feels persecuted and decides to delete his comments, I've webcited the page as I saw it when I wrote this post. See here.

For even more uninformed commentary if you're feeling mentally masochistic, you might check out this story's coverage on Creation-Evolution Headlines [link]. It's not drastically different from Michael's comments, so I wouldn't recommend readers put themselves through the pain of reading the same type of nonsense twice.

So if you're looking for some relief from this garbage and would like to read some informed commentary on Nagashima et al.'s paper, look no further than Ed Yong's Not Exactly Rocket Science -- "How the turtle got its shell through skeletal shifts and muscular origami"

Way back when Odontochelys was first published, Matt Celesky put together a link list of articles and blog posts put out on it. See here

Some relevant/recent publications:
Joyce, W. G. et al. 2008. A thin-shelled reptile from the Late Triassic of North America and the origin of the turtle shell. Proceedings of the Royal Society B, doi: 10.1098/rspb.2008.1196
Li, C. et al. 2008. An ancestral turtle from the Late Triassic of southwestern China. Nature, 456: 497-501. doi:10.1038/nature07533
Lyson, T. and Gilbert, S. F. 2009. Turtles all the way down: loggerheads at the root of the chelonian tree. Evolution and Development, 11: 133-135. [see the numerous references herein]
Nagashima, H. et al. 2009. Evolution of the turtle body plan by the folding and creation of new muscle connections. Science, 325: 193-196, doi: 10.1126/science.1173826
Reisz, R. and Head, J. 2008. Turtle origins out to sea. Nature, 456: 450-451, doi: 10.1038/456450a
Rieppel, O. 2009. How did the turtle get its shell? Science, 325: 154, doi: 10.1126/science.1177446

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