Throughout 2004 I worked on a series of short animations/illustrations with UC Berkeley professor of Paleontology Kevin Padian and a graduate student in his lab Randall Irmis.

Pterosaurs One project involved an analysis of Pterodactylus suevicus. Here is a hybrid animal with the proportions of Pterodactylus suevicus and the bones of Ramphoryncus muensteri. I used a record of fossil bone lengths to estimate a hypothetical average P. suevicus.

The above diagram was traced from original fossils by Kevin Padian and originally published in 2004


I modeled these bones after a series of very detailed drawings of Ramphorhyncus Muensteri and scaled them to match to proportions of Pterodactylus suevicus. This model was then animated to match footsteps of an unidentified pterodactyl that left fossilized footprints. The motions are based on research by Professor Padian, who also produced interesting animations of the same site without bones. One area of interest is the joint between the humerus and the scapulocoracoid I used this script in Maya to check for interpenetration of the scapulocoracoid and the humerus.

rigidSolver -e -ctd on rigidSolver;
string $count = " ";
for ($i = 6; $i<10; $i++)
{
group -em -n ("delete"+$i);
currentTime $i;
$count = " "+ $count + "frame" + $i;
for($k =1; $k <13; $k++)
{
string $new1[] = `duplicate -rr -renameChildren ("pSphere"+$k)`;
parent $new1[0] ("delete"+$i);
string $rigid = `rigidBody -active $new1[0]`;
string $addcount = `rigidBody -cc $rigid -q`;
$count = $count +" "+$new1[0] + " " + $addcount;
}
delete ("delete"+$i);
}
print ($count);

Revueltosaurus

Above image from "Homology of Facial Structures in Extant Archosaurs (Birds and Crocodilians)..." Witmer.

In 2004, Irmis discovered the fossilized remains of an animal known at the time as a dinosaur: Revueltosaurus Callenderi. After looking at the hips and ankles, Irmis decided that the animal was much more closely related to crocodiles than dinosaurs; it is most likely an Archosaur. This discovery changed a lot of assumptions about dinosaur lineage, because these kind of teeth alone are no longer sufficient evidence to classify an animal as an "ornithischian."

Here's my first reconstruction of Revueltosaurus callenderi :)

And here are some more attempts made with super sculpey, based on musculature that I inferred from Crocodiles, Alligators, and a Crocodylian named Desmatosuchus haplocerus, described in detail in an article entitled "Cranial anatomy of D. haplocerus" by Bryan J. Small.

Above is an animation I made showing the my reconstruction of the jaw muscles of Revueltosaurus. Below is an excerpt from an essay I wrote about the dorsal pterygoideus muscle:

"The placement of the dorsal pterygoideus muscle in the jaw of basal archosaurs raises an interesting phylogenetic debate. Many scientists have sought to explain the presence of the antorbital fenestra diagnostic of archosaurs with the development of the dorsal pterygoideus (Witmer 1997). They propose that the antorbital cavity and fenestra developed in Archosaur skulls to accomodate enlargement of the dorsal pterygoideus and to either facilitate muscle origins in the lacrimal/maxillary fossa of the cavity or provide room for a bulging adductor muscle (Witmer 1997). Living crocodylians possess a dorsal pterygoideus that occupies this cavity, but living birds do not. Both are archosaurs, so they respectively support and negate the general hypothesis. Neither animal, however, shows any indication that the dorsal pterygoideus attached to the rim of the antorbital fenestra as seen in the pseudotemporalis muscle and the superor temporal fenestra of nearly all diapsids (Witmer, 1997). Witmer reviews the fossil record extensively and concludes that the pterygoideus probably never attached anywhere along the ridge of the antorbital fenestra because no evidence of bone scarring exists to support this idea and the lip of the antorbital fenestra is too thin (Witmer, 1997, pg. 13). He also concludes that basal archosaurs probably exhibited dorsal pterygoideus attachment in the dorso caudal portion of the antorbital cavity- along the palatine and pterygoid, but that this attachment does not likely provide an explanation for the presence of the cavity itself (he eventually finds that basal archosaurs used the cavity to house an air sac)."

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