Fœtal Dinosaurs.
Remains of a very small dinosaur were found in immediate relation with the type specimen of Morosaurus grandis. These remains, which consist of a complete femur, the larger portion of both humeri, and several vertebræ, show no essential differences from the large specimens except in size, and indicate an animal of perhaps seven feet in length, and little more than two feet in height. The imperfect ossification of these bones indicates that the animal was very young, and it seems probable that it was fœtal. The only other similar case known in the Dinosauria is the apparent embryo observed by the writer in Compsognathus.[1]
Classification.
The various genera of the Sauropoda, and in fact of the Dinosauria in general, cannot at present be distinguished by the detached teeth. In one form, however, the teeth are quite peculiar, and the dentition appears to offer generic characters. The maxillary teeth of this form have been referred to Stegosaurus (this Journal, vol. xix, p. 255; pl. vi, figs 4 and 5), as they were first found in connection with the remains of that genus. Later investigations indicate that they belong to the Sauropoda, and there is some evidence that they are the teeth of Diplodocus.
The main characters of the order Sauropoda, and of the two families now known to belong to it, are as follows:
Order Sauropoda. Herbivorous.
Feet plantigrade, ungulate; five digits in manus and pes; second row of carpal and tarsal bones unossified. Pubes projecting in front, and united distally by cartilage; no post-pubis. Fore and hind limbs nearly equal; limb bones solid. Sternal bones parial. Premaxillary bones with teeth. Precaudal vertebræ hollow. Each sacral vertebra supports its own transverse processes.
Family Atlantosauridæ. Anterior vertebræ opisthocœlian. Ischia directed downward, with extremities meeting on median line. Anterior caudals with lateral cavities. A pituitary canal.
Family Morosauridæ. Anterior vertebræ opisthocœlian. Ischia directed backward, with sides meeting on median line. Anterior caudals solid. Pituitary fossa only.
- ↑ This Journal, xxii, 340, November, 1881.
