Comments on: Mystery Dissection 6

By: John Scanlon, FCD

John Scanlon, FCD — Sun, 13 May 2012 06:39:39 +0000

With regard to armadillo musculature, it would be interesting to learn how, when scared, they are able to make vertical jumps to a body-length or so from the ground. Must be a bit of power there.

(…you just get a leg up and you slap it on down, and you find you’re up in what’s called a bound… – Jackalope in Pixar’s Boundin’)

By: paleomanuel

paleomanuel — Thu, 10 May 2012 17:06:03 +0000

Thank you very much John and Casey! although there are few working on Xenarthrans all tips are good to follow!

By: John of the Freezers

John of the Freezers — Thu, 10 May 2012 14:57:15 +0000

I shall keep you in nervewracking suspense no longer. As usual, we have some brilliant anatomists providing guesses, and they basically got the answer — mostly. It is crocodylian skin, from the hindlimb region around the knee (well done, Casey and Mark!).

BUT (cue pedantry!) the colour is a clue, although it is a very subtle clue at that, and cruelly blackhearted of me to be so subtle. This is not a crocodile but a Black Caiman, Melanosuchus niger; details here: http://crocodilian.com/cnhc/csp_mnig.htm
Somewhat endangered, rather little known, and very cool. We got one (>2m long) from a crocodile farm a few years ago and are still making the most of it thanks to our freezers.

The skin pattern is pretty close to what some dinosaur skin might have looked like (pebbly), albeit with less ossified tissue (scutes/armour) inside the skin in some species of dinosaurs. A billion nice examples are here: http://bit.ly/K1Uo0H
Hadrosaur (duckbill) skin is surprisingly common in the fossil record, so we do know a fair bit about that, and skin is known from quite a few other groups/species of dinosaurs… but I digress. Melanosuchus is awesome even without mentioning dinosaurs (Casey you can pay me my fee now for saying that, thanks very much). Hooray for M. niger, and hooray to today’s winners!

By: John of the Freezers

John of the Freezers — Thu, 10 May 2012 07:23:43 +0000

OK looks like comments have ebbed, so I’ll give the answer later today!

By: Casey

Casey — Wed, 09 May 2012 04:19:20 +0000

Dillos don’t have much for muscles since they’re worm and bug eaters. Robert McAfee and Virginia Naples are the only people I know of that have worked on xenarthran muscles very much. Check out Robert’s most recent paper which includes muscle maps. I’m sure the lit cited in that paper will also help.

McAfee, RK. 2011 Feeding mechanics and dietary implications in the fossil sloth Neocnus (Mammalia: Xenarthra: Megalonychidae) from Haiti. Journal of Morphology, 272: 1204-1216.

By: Mark Robinson

Mark Robinson — Wed, 09 May 2012 04:08:17 +0000

First thought is skin from the underside or inside leg of a small croc. The scutes(?) are smaller and more numerous toward the top suggesting that more flexibility is required but protection is less critical, so that might be toward the midline or throat if belly skin.

There appears to be a flexion point at about 122mm so I’d guess that, if it’s a limb, that might be the crook of an “elbow” or back of a “knee”, otherwise where the limb meets the body.

As for where from, that’s easy – one of your freezers!

By: John of the Freezers

John of the Freezers — Tue, 08 May 2012 18:58:58 +0000

Thanks Manuel! Cranial musculature– I am pretty useless with that, to be honest. Casey Holliday, who fortuitously commented above, would be a great guy to ask about that. Armadillo dissections are something I’ve never come across in my own work or in the literature. I cannot think of any good references… sorry! You’ve stumped me! Xenarthran workers like Gaudin and colleagues would be a good start for some leads. Good luck!

By: paleomanuel

paleomanuel — Tue, 08 May 2012 18:47:47 +0000

Hi John, Congratulations for the blog!
I’m starting to work on the cranial musculature xenarthrans for some paleontological reconstructions, I wonder if you can recommend me some literature, contact, or source of images of dissections of actual armadillos.
greetings and thanks!

By: Casey

Casey — Tue, 08 May 2012 13:09:24 +0000

Pebbly Crocodile skin. Probably from an arm or leg. You said skinny, so I’m going to guess C. johnstoni.

By: hypnotosov

hypnotosov — Tue, 08 May 2012 13:06:46 +0000

A piece of a skin from the belly of a Water Monitor?