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January 1, 2012
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Silesaurs R Us by Qilong Silesaurs R Us by Qilong
Two Silesaurus opolensis, that odd beaked pre-dinosaur with the odd limbs and such. Awesome teeth. More a study of making these near-dinosaurs into more croc-like figures, including the heavily scaled tail rather than a slender, pebbly-textured one. I kind of flubbed it on the squamation, and have been sitting on this for the last year simply because I wasn't perfectly satisfied with what I was trying to do with it (the tail is incomplete). But I won't finish this peace because of that, and will rather redo something similar.
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:iconspongebobfossilpants:
Silesaurid question: What did Eucoelophysis look like? I'd assume it was a typical silesaurid, but it must've had odd proportions if it was assigned to Coelophysidae...
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:iconqilong:
There's very little preserved to let us know this. What is apparent is that some of the material originally used to describe it is, actually, coelophysoid in nature. So that pretty much explains some of the confusion.
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:iconeriorguez:
Aw, I also came to talk about pronation... :(

Good work anyway; you got the oddness of these critters quite neatly; looking like neither a theropod/early saurischian, nor a primitive ornithischian, but similar to both.
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:icontomozaurus:
Tomozaurus Jan 2, 2012  Student General Artist
Pronated hands? :/
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:iconqilong:
As pronated as any quadrupedal archosaur. This is required to place the third manual digit into an anteriorly oriented position, as in crocs, ornithischian and sauropodomorphans should be. Note that because I infer the limbs as quadrupedally inclined, the manus pronates to walk on, then supinates for grasping ... if that was even possible, as a good manus is unknown in ol' Sile hands there.
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:iconmattmart:
MattMart Jan 2, 2012  Hobbyist Digital Artist
Nope, ceratopians have the first or second digit in anterior position with the third and fourth pointing laterally. Sauropod hands are indeed pronated but this comes from a locked-in twist to the forearm bones. Crocs third digit points forward because of the splayed forelimbs, they are unpronated. Pronation is a derived condition that arose in sauropods and... that's about about it, maybe hadrosaurs? not sure about that one.

Beautiful drawing otherwise, your detail work, scales, teeth etc. are stunning!
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:iconqilong:
Double checking with Fujiwara's 2009 article, which at the least points the primary anterior axis at digit 2 or between digits 2 and 3. Senter, in various publications, has shown that the manus forms an columnar-like arcade and has been mis-reconstructed in a variety of basal ornithischians, especially stegosaurs and ankylosaurs. Data from ceratopsians is pending, but my impression is, besides that the arm is already very weird in that it's held in a semi-sprawling posture unlike other dinosaurs, the manus orientation is somewhat unique; the main manus oritentation is still "forward," and not "sideways,' with the primary manus axis being oriented through the second to third digits (not the first as implied).

I don't disagree with dissenters on this point, and the technical issue should be resolved before I absolutely defend bunny-hands on silesaurs. There is a mechanical reason for this, at least while its actually standing on all fours. Perhaps relaxation of the manus supinates it and you get a characteristic "palms in" while on twos, but at the moment I cannot strong evaluated this. In most quadrupedal animals, the primary axis of the manus follows the most robust metacarpal, largest digit, etc., and we can presume, without tracks, that this is true for silesaurs which should a typical "third is largest" digit with what's preserved. The arm anatomy is very similar to other elongate-limbed animals, such as the running crocs and hadrosaurs, and at the time I simply swapped in the "third is anterior" model from those taxa and plopped it on this near-dinosaur, instead of trying to perform a unique study.

[link]

Fujiwara S.-i. 2009. A reevaluation of the manus structure in Triceratops (Ceratopsia: Ceratopsidae). Journal of Vertebrate Paleontology 29(4):1136-1147.
Senter, P. 2007. Analysis of forelimb function in basal ceratopsians. Journal of Zoology 273:305–314.
Senter, P. 2010. Evidence for a sauropod−like metacarpal configuration in stegosaurian dinosaurs. Acta Palaeontologica Polonica 55(2):427–432.
Senter, P. 2011. Evidence for a sauropod-like metacarpal configuration in ankylosaurian dinosaurs. Acta Palaeontologica Polonica 56(1):221-224.
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:icontomozaurus:
Tomozaurus Jan 2, 2012  Student General Artist
Uh, far from all quadrupedal archosaurs have pronated hands. Pterosaurs, ceratopsians, and camptosaurids, to name a few, are all quadrupedal with supinated hands. Pronation actually seems to be a quite derived condition in archosaurs appearing only in advanced sauropodomorphs and hadrosaurs among dinosauria. I haven't looked into it, but don't think crocodilians actually have pronated hands either, the sprawled limbs just make it appear to be the case. This is what I have heard any way, I'm not sure for the rest of pan-crocodilia though.
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