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Cretaceous Alligatoroid by ScottHartman Cretaceous Alligatoroid by ScottHartman
Rounding out the archosaur family tree, I've done several croc and croc-relatives of late. This is Brachychampsa, and the specimen is from the Late Cretaceous of North America.
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:iconspuderific:
Spuderific Featured By Owner Mar 5, 2012
Never smile at a crocodile.
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:iconroccenere:
RocCenere Featured By Owner Feb 18, 2011  Hobbyist Digital Artist
So the scales on its back are actually bony protrusions? Not 'scales' at all?
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:iconevenape:
Evenape Featured By Owner Feb 18, 2011  Student Traditional Artist
Isn't that obvious?
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:iconroccenere:
RocCenere Featured By Owner Feb 18, 2011  Hobbyist Digital Artist
Sweetheart, there was no need to be rude.

To the artist: My initial confusion originates from my lack of exposure to a crocodilian skeleton complete with scutes. Through a touch of research, this has been remedied.
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:iconevenape:
Evenape Featured By Owner Feb 18, 2011  Student Traditional Artist
Well, sorry, I don't intentionally rude, just pointing out something
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:iconscotthartman:
ScottHartman Featured By Owner Feb 18, 2011  Professional Digital Artist
Not a problem. They are indeed bony scutes, as you've discovered. There's actually a ton of information that can be gleaned from the scutes, not just functionally but also for elucidating the relationships of the croc family tree.

I've done 3 croc skeletals so far, and the scutes are the most different part of them (with the skulls a close second).
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:iconroccenere:
RocCenere Featured By Owner Feb 19, 2011  Hobbyist Digital Artist
What kind of differences are particularly evident in the scutes? I had a browse through photographs of living crocodilian species just then, and to my untrained eye, I can't pick out anything particular.
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:iconscotthartman:
ScottHartman Featured By Owner Feb 19, 2011  Professional Digital Artist
Some animals have very rounded scutes, some have very square ones. Some have both. There are different numbers of rows in different groups. Some have very tall spines on the tail, some (like Brachychampsa) have quite low tail spines. If you look at them up close there are often differences in the way blood vessels have made holes in them as well, and other morphological differences you wouldn't see in a skeletal reconstruction (or a photo that shows the whole animal).

Often a good croc paleontologist can identify the group, or even the genus, just by looking at a couple of pieces of armor. Now I'd be lucking to be able to put them into even the most general of groups based on the scutes, but then I don't work much on the croc-relative side of the archosaur family tree.
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:iconroccenere:
RocCenere Featured By Owner Feb 19, 2011  Hobbyist Digital Artist
Oh wow, that's very interesting. Thanks for taking the time to tell me this. (: I always have liked crocs and their extinct ancestors, it's a shame that I, to be honest, know very little about them.
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:iconscotthartman:
ScottHartman Featured By Owner Feb 19, 2011  Professional Digital Artist
If you go back and look at some fairly primitive croc relatives, like Effigia, you can see how weird and diverse they were.

Still, in the grand scheme of things they're really not my specialty either, although I do try to keep abreast of the literature on them when I can.

Anyways, you're welcome. I only post these on DA to be something of an educational source for artists anyhow. :D
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(1 Reply)
:iconamorousdino:
amorousdino Featured By Owner Feb 17, 2011  Student General Artist
is it from da Maastrichtian part of da Late Cretaceous?

Cuz I've been looking for a crocodilian to draw with my tyrannosaurs =D
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:iconscotthartman:
ScottHartman Featured By Owner Feb 18, 2011  Professional Digital Artist
It's actually a little older than that, but it should be close enough to its Maastrichtian relatives to use.
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:iconbruisedeye:
bruisedeye Featured By Owner Feb 17, 2011  Hobbyist Traditional Artist
Not a critique or a comment, really, but I'm dying for you to do a run on some Crurotarsans. Or Gorgonopsids. Ooooohhh....or Mesonychids!

Really, though...where do you get the raw data for your illustrations, and how do you go about assembling poses? Do you scan through the functional morphologic literature to best articulate things, or do you just go by "gut feeling"?
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:iconscotthartman:
ScottHartman Featured By Owner Feb 18, 2011  Professional Digital Artist
I think this will have to have one of those numbered sets of responses:

1) I'd also love to do a run on those groups. The project I was working on forced me to spend a lot more time away from the dinosaur "comfort zone", so depending on what time and projects look like I may indeed get to work on some of these groups.

2) I always gather all the relevant papers on a taxon before I start, as well as and photographs and additional measurements I can scrounge up (I've measured many dinosaur skeletons myself, and when I do work for museums or other researchers I can usually coax measurements from them to ensure accuracy). With dinosaurs the people are my colleagues and often friends, so I may also send them versions for critique. Honestly, the data gathering and subsequent scaling work often makes up 50% or more of the time involved in a skeletal reconstruction.

3) Poses: I have a large library of functional morph (my paleo and biology collection covers four full-size bookcases, and my pdf collection dwarfs the print material). When restoring animals with close functional descendants (like crocs) I also load up on photographs of living animals moving at different speeds to double check myself with. This can be a lot of work when I do a reconstruction of an animal that is totally new to me, but vertebrates are remarkably conservative in their movement patterns, so after doing one member of a group it's a lot easier to do more.

I hope this is an interesting "peek behind the curtain". At some point I want to create some tutorials on my process, since I know it's different from that used by others in the field. But that's on a long list of things I want to do if I can find the time.
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:iconbruisedeye:
bruisedeye Featured By Owner Feb 18, 2011  Hobbyist Traditional Artist
Thanks for the replay; interesting is the least I can say about it!
My current work wouldn't require anything like this (being for the most part statistical analysis of morphologic features) but I've always admired your skeletal drawings and would love to start attempting them myself.

Do you utilize extant animal musculature diagrams to flesh out the silhouette?
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:iconscotthartman:
ScottHartman Featured By Owner Feb 19, 2011  Professional Digital Artist
For the musculature I make my own muscle diagrams, based on dissections of living animals and mapping origin and insertation points against phylogeny. There has been some excellent work in the literature on doing this for dinosaurs, so I frequently incorporate published work into those soft tissue reconstructions.

I should note that many of my older skeletals on DA are slightly out of date. I've embarked on a project to bring every skeletal I've ever done up to current standards, but since I've done 140 or so that takes a very long time. I've done about 30 so far :P

On the other hand, most of the time when I update them people don't notice the differences, so I'm not too worried about leading people astray either.
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February 17, 2011
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