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Re: dino finger scutes?



From: "Andrew A. Farke" <andyfarke@hotmail.com>
Subject: Re: dino finger scutes?


> Do all birds have scutellae on their feet? How about crocs? I seem to
recall
> that the latter don't, but I could be wrong.

It's a little confusing because the term scutellae seems to be applicable to
everything from slightly keratinized scales to full-on osteoderm-embedded
scutes, but compared with bird scutellae the scales on croc legs and feet
are similar and equivalent. Examine the following two images:

http://crocodilian.com/cpor-backfoot-midres.jpg
http://crocodilian.com/cjoh-backfoot3.jpg

The first shows a medium resolution image of a juvenile saltwater croc hind
foot. Most of the scales (or scutellae) on the upper surface are thickly
keratinized. If you look closely, you can even see minor keeling due to
dense collagen fibers within the dermal layer. The anterior/caudal part of
the leg has a row of what I like to call "mercurial" scales running down
them. These contain higher densities of collagen and are quite tough and
inflexible.

The second image, the underside of a juvenile freshwater croc foot, shows
these "mercurial" scales quite well on the outer edge. Looks familiar,
doesn't it? You can also see that  the underside of the foot is covered by
thousands of tiny, soft scales with a much lower keratin content. These are
actually identical to those on the underside of bird feet (in terms of
composition, and their DNA coding).

Adam