Article: The postcranial skeleton of the earliest dicynodont synapsid Eodicynodon from the Upper Permian of South Africa
B. S. Rubidge, G. M. King and P. J. Hancox
Comparison of postcranial skeletal elements of the Upper Permian Eodicynodon oosthuizeni (the earliest member of the Dicynodontia) and other dicynodonts, shows distinctive features of the Eodicynodon humerus, scapula, femur and ilium which are diagnostic at the generic level, and which may therefore aid stratigraphical studies.Both the fore- and hind limbs and girdles show a less derived condition than in other dicynodonts. The forelimb adopted a sprawling position and was supported by extensive postural musculature as evidenced by the broad blade of the scapula where the serratus anterior and levator scapulae attached, and by the large ventral girdle for attachment of the pectoralis and coraco-brachialis. The more distal insertions of the deltoideus and pectoralis muscles on the delto-pectoral crest suggest that the characteristic slow and powerful forelimb action of later dicynodonts was not yet in evidence in Eodicynodon. It appears that the hind limb adopted a sprawling or semi-sprawling position. The femur lacks a developed trochanter major, and the ilium is without marked anterior and posterior processes. The ilio-femoralis was predominantly an elevator, retraction of the femur having been carried out by the caudi-femoralis and ventral musculature attached to the extensive pubo-ischiadic plate.