Yesterday I wrote about turtles. Turtles are awesome. Their shell is made of bone. Bone! Ok, the part you actually touch, the outside, is made of – guess what – tortoiseshell. It’s something like horn. But under that, the hard stuff is made of ribs and vertebrae, fused together. You can see it in the green turtle skeleton at left – sea turtles like this one have big holes in their shell because they don’t really need as much shell as land turtles. (In a land turtle skeleton, that would all be solid.)
Anyway, the truly wacky thing about this arrangement is that the shoulder blades are in front of the ribs. In front! That is weird! As evolutionary morphologist Ann Burke told me: “If you take a deep breath and shrug your shoulders, you realize how bizarre it would be if your shoulder blades were stuck inside your ribcage.” Tetrapods like you and me and cats and birds, we pretty much all have more or less the body plan. But not the turtles. They’re all, “Hey, watch, guys, I can put my ribs behind my shoulder blades.”
I was using my highly sophisticated technique for finding sources who are named in the references of an article – googling burke turtle evolution - and it seemed like, whoever I named, I would get a link to this article from creation.com. So, that’s interesting. Several scientists I talked to mentioned that turtles do more or less spring fully formed into the fossil record. To creationists, that means someone must’ve placed them there.
This whole thing really made me want to go down to the National Museum of Natural History and look at the turtle skeletons. It’s very old-school: a big long hallway with unsexily displayed skeletons, like this. I love it.
art credit: FCIT
P.S. Hey, I just noticed: this is my 100th post on this blog! Howdya like that?