Fauna and Stratigraphy of the Stormberg Series. 357 



In some Dinosaurs the post-temporal vacuity is closed. In Sphenosuchns 

 it is very small, much smaller than in the Phytosauria or genera 

 like Euparkeria. 



The skull has a smaller quadrato-jugal than Euparkeria, but shows 

 an advance on that form in the loss of the interparietal and the 

 reduction of the lachrymal. 



Chief interest lies, however, in the post-cranial part of the skeleton 

 and in the lack of armour. This latter feature is noteworthy as the 

 larger number of the genera comprising the order Thecodontia, to 

 which this form was originally assigned, possess armour in the form 

 of scutes which are sometimes numerous and heavy. No armour 

 has, however, yet been seen in Thecodontosaurus, Massospondylus, 

 and the genera of the Saurischia. 



The shape of the coracoid (erroneously described in the original 

 description as the clavicle) is unique among reptiles, and strongly 

 resembles that of many Birds. Among Reptiles, it is approximated 

 most closely by the bones in Notochampsa and the Crocodilia. Eupar- 

 keria has a rounded coracoid, and so has Massospondylus, so that 

 Sphenosuchus cannot be ancestral to the latter nor to the Saurischia. 

 Its humerus and tibia, however, are more like those of the Saurischia 

 and Massospondylus and its allies than other Archosauria; and the 

 shape of the distal end of the tibia shows that the astragalus was 

 probably fairly immovably fixed to the tibia. Further, the possible 

 lack of clavicles is important. The other bones of the scapular arch 

 are so well preserved and so nearly in place that it is scarcely 

 possible to suppose that bony clavicles, if present in the living animal, 

 were not preserved. Lying anterior to the arch and dissociated from 

 the scapula and coracoid is a thin elongate bone - - not complete - 

 which might be a clavicle or a neck rib or even a long bone of the 

 hyoid arch similar to the ceratobranchial described by Broom in 

 Euparkeria. The absence of clavicles would remove the form alto- 

 gether from the order Thecodontia. Further, it could only be put 

 with difficulty into the Saurischia on account of its peculiarly spe- 

 cialised coracoid, which must be taken as a proof of a certain simi- 

 larity in musculature between this form and the Birds. On the other 

 hand, the coracoid is more elongate and birdlike than that of 

 Archaeopteryx, which has already acquired feathers; and it is probable 

 that this peculiarity in the coracoid of Sphenosuchus is merely a 

 specialisation which was not a step on an advance from the Reptile 

 to the Bird. The absence of clavicles would prevent Sphenosuchus 

 from being on the direct line of evolution of the class Aves. 



Taking all the facts into consideration, it is necessary to found 



