DrScottHartman's avatar

Postosuchus big and small

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For such an iconic Triassic archosaur, Postosuchus has proven lots of trouble when it comes to restoring what it looked like and how it got around. Getting the proportions right isn't a trivial matter, as none of the remains are so completely preserved/prepped/described that they can stand in for an entire skeleton. Simple cross-scaling of the specimens isn't possible, as they are of different sizes and exhibit allometric scaling (more on that in a sec).

With a bit of care I've managed to pull together a reasonable composite based on (and scaled to the size of) the type specimen, TTU-P 9000. One of the larger sticking points (in part related to getting the proportions correct) has been if and to what degree Postosuchus was bipedal. While the forelimbs are robust for their size, recent work has noted that the forelimbs are substantially shorter than the hind limbs, which at least in the type specimen I heartily agree with.

One thing that is interesting, however, is that the smaller paratype specimen TTU-P 9002 has different limb proportions - the forelimbs are quite a bit longer relative to the hind legs, and in fact are nearly as long as in the substantially larger type specimen. I've scaled down the skull and axial skeleton to match the limbs of 9002 in the smaller skeletal above. It's tempting to infer that the young of Postosuchus were quadrupeds (or at least were _more_ quadrupedal), and as they grew Postosuchus spend more time on its hind legs alone.
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anonymous's avatar
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GodzillaLagoon's avatar
Are you planing to draw more rauisuchians ?
QuazarShark's avatar
Oh no the people legs
I don't know much about paleontology (at least comparatively to the rest of the commenters here) but having previously only been familiar with the former quad look thanks to a model I own, the memester in me is now sorely tempted to make a "birds with arms"-esque version of this with photorealistic human legs attached hfgjfgt
Alior0645's avatar
TheUltraCube6723's avatar
Wasn't there a new skull of this fella discovered? Or am I misremembering something

Also, the skull of this fella really reminds me of Tyrannosaur skulls for some reason, mainly cause of the shape of the orbits, and the nose, as well as the teeth.
DrScottHartman's avatar
You are correct, there are two specimens with good skull material. FWIW the skulls reminded Chatterjee of tyrannosaurs as well, in fact he proposed that tyrannosaurs might have evolved from these guys rather than other theropods. For a lot of reasons this never real caught on, but I agree with you (and him) that they do have a superficial resemblance, at least in side view.
TheUltraCube6723's avatar
wait he really thought Tyrannosaurids evolved from these guys? WHEEZE
DrScottHartman's avatar
Chatterjee seemed to really want to tie various derived theropod groups back to Triassic origins - maybe as part of his world view that Protoavis was an early bird, but phylogenetics kept placing the origin of birds higher up in the theropod tree? 
TheUltraCube6723's avatar
do you think we should tell him protoavis is just a chimaera.
DrScottHartman's avatar
Hopefully by now he knows?
Lucas-jorquera's avatar
hello Mr. Scott, I just created an account on this page, I've been seeing your skeletons for a while, until a few weeks ago I thought he was dead (I was wrong) has interesting projects, if you can suggest ideas for new skeletons these are my proposals : saurolophus angustirostris, saurolophus osborni, sinosauropteryx prima, corythosaurus casuarius, jinguofortis perplexus, xiaotingia zhengi, eosinopteryx brevipenna, serikornis sungei, changyuraptor yangi, shenzhousaurus orientalis, ichthyornis dispar, hesperornis regalis, titanis walleri, gastornis gigantea, dromornis stirtoni, genyornis newtoni, incisivosaurus gauthieri, avimimus portentosus, citipati osmolskae (the normal, not the sp) beipiaosaurus inexpectus, linheraptor exquisitus, shanweiniao cooperum, archaeorhynchus spathula, ningyuansaurus wangi or zhenyuanlong suni.
All these taxa have never been properly restored despite the good material with which they count, saurolophus angustirostris is known for at least 15 specimens, changyuraptor is known for a beautifully preserved full skeleton and most enantiornithes are never restored. You would be the first
DrScottHartman's avatar
The good news is that some of these are done (but still under embargo) while others are in-progress. The bad news is that I am teaching a new course this semester which is an enormous time sink, and I'm also trying to finish up my dissertation, so there probably won't be very quick progress (well...until a chunk of skeletals come off of embargo this summer, then I guess you'll get to see some action).

Lucas-jorquera's avatar
It's good to know, take your time and good luck with your work
Dinopithecus's avatar
Would this creature have had a M. pterygoideus anterior that extended into the antorbital fenestra, or at least some sort of jaw-closing muscle? What about other archosaurs (like dinosaurs)? There used to be some reconstructions of carnivorous dinosaurs with an antorbital fenestra filled entirely with that muscle (though to be fair, they still persist), but clearly they're not accurate anymore (Lawrence Witmer told me that no one argues for that anymore); that would have been filled in largely with air sinuses. But would there still have been a jaw closing muscle in there, even if it didn't completely take up the space in the fenestra?
OmarRobles523's avatar
Really like it tbh, might be useful for pivot prehistoric animators that can make a Postosuchus stk. Still wondering, do you take suggestions for people that want a good skeletal of the creature they suggest to you?
Phillip2001's avatar
Wait, I am a pivot prehistoric animator too!!!! :O But we already have two of them.
DrScottHartman's avatar
I always read suggestions, but I rarely have a chance to take them. Almost all of my work is commissioned, and when it's not it's because I need it for research or publication.
Kazuma27's avatar
Did crocs mimic theropods or theropods did mimic triassic "crocs" (and bear in mind i'm using the term "croc" in the broadest way possible)?
DrScottHartman's avatar
Or did some crocs mimic other bipedal crocs??
purple-hermit's avatar
It's always exciting to see new developments in skeletal reconstructions; I grew up watching Walking with Dinosaurs, so Postosuchus holds a pretty special place in my heart.
DrScottHartman's avatar
Back when that came out I thought they'd made a good decision with making it quadrupedal. Ah well, live and learn!
Santi801's avatar
Could you possibly do a skeletal for Fasolasuchus?
DrScottHartman's avatar
I'd probably have to do Saurosuchus first, as the description of the type material leaves something to be desired in terms of making a skeletal reconstruction. There's an odd chance I may get to do Saurosuchus later this year, so if you see that posted ask again.
Afterfilth's avatar
Those weeny hands, it's like a prehistoric Trump.
anonymous's avatar
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