The postcranial skeleton of the Hyposaurinae (Dyrosauridae; Crocodyliformes)

Abstract

Abstract: A detailed description of the postcranial skeleton of the Hyposaurinae is presented, based on the hitherto known and new postcranial material. The postcranial skeleton of the hyposaurine Dyrosauridae differs from that of all other crocodilians by the high neural spines, which can reach up to four times the length of the vertebral body, thoracic ribs, which are five times longer than the adjacent vertebral body, dorsal osteoderms lacking an external keel, deep haemal arches, which reach up to 3·4 times the length of the vertebral body, an ilium with a prominent craniodorsal tubercle, and a scapula with an expanded and lateromedially flattened scapular wing, which makes the scapula 1·5 times as large as the coracoid. The similarity of the postcranium of Dyrosaurus, Hyposaurus, Congosaurus and Rhabdognathus allows a uniform skeletal reconstruction for the Hyposaurinae. Only fragmentary material is known from the Phosphatosaurinae. The comparative osteological description of all hyposaurine specimens known to date establishes a basis for future constructional morphological analyses and the reconstruction of their evolutionary history.