Effigia okeeffeae (Nesbitt and Norell, 2006) Carnian, Late Triassic, ~210 mya, ~ 2 m in length, was originally considered an early theropod dinosaur by Colbert, who collected the specimen in the late 1940s but never removed it from its jacket. A recent reassessment by Nesbitt and Norell (2006) and Nesbitt (2007) nested Effigia among the poposaurid rauisuchians based largely on the ankle, which they reported articulated in a crocodile-normal configuration, with a morphology similar to Alligator (see below). The broken and missing calcaneal "heel" would have turned proximally, like that in sister taxa, Shuvosaurus and Turfanosuchus.
Distinct from Shuvosaurus, the skull of Effigia had a longer premaxilla and the back of the skull dropped nearly to the former occipital plane. The occiput likewise rotated ventrally. Nesbitt and Norrell (2006) identified the tip of the mandible as the dentary, but it is the greatly expanded predentary, as in Lotosaurus and Silesaurus. The dentary is that short strip dorsal to the very large mandibular fenestra, where it typically appears.
More cervicals were present in Effigia. All the neural spines were relatively low.
The scapula and coracoid were massive, as in Lotosaurus, but the forelimbs were nearly vestiges, especially the manus. Evidently the hand was rarely used, but it did retain a robust metatarsal and proximal phalanx of digit 5.
The pelvis was similar to that of Shuvosaurus, but without the ventral "boot." The hind limb was more robust with arelatively longer foot, equal to the tibia in length. The larger foot kept the center of balance over the toes. |
