Anatomy of An Archosaur

Effigia has a different anatomy from the extant crocodiles and alligators that we know today. The femoral head, astragalus (the "ankle"), and the proportions of the manus (front "paw") have been discussed at length this week in terms of their being different and how they are different. The remainder of the anatomy (almost an entire animal) has not been heavily discussed. We mentioned that Effigia has shorter forelimbs than hindlimbs, making it a facultative quadruped that, when on four feet, angled downward rostrally. The cranium of Effigia is the most complete portion of the fossil animal, though the mandible of the archosaur is not known. A reasonable reconstruction of the mandible exists and the inferences that generated it came from the existing cranial elements as they were informative about the general morphology of the entire head.