CERATOPSIDAE, Marsh, 1888

Carpenter, Kenneth, 1982, Baby dinosaurs from the Late Cretaceous Lance and Hell Creek formations and a description of a new species of theropod, Contributions to Geology, University of Wyoming 20, pp. 123-134 : 131

Family CERATOPSIDAE

Fig. 10

Material: Teeth: UCM 37878 (UCMP-V5711) H 6 mm, W 3.8 mm; UCM 43526 (UCMP-V5711) H 2 mm, W 2.5 mm; UCM 45057 (UCMP-V 5711) H 3.6 mm, W 3.8 mm; UCM 45058 (UCMP-V 5711) H 3.5 mm, W 4.1 mm; and UCM 45059 (UCMP-V5711) H 4 mm, W 3.7 mm.

Discussion: Only UCM 45059 is heavily worn. Unworn teeth have a triangular enameled face with a vertical medial ridge ( Fig. 10 ). Small denticles are present along the upper edge of the enameled surface. Unlike adult ceratopsian teeth, these have a single unbifurcated root, a condition Hatcher and others (1907) noted for young incipient teeth. It is doubtful that these small teeth are incipient teeth of an adult, because they are well developed and have a long root, which is unlike the short, thin-walled, open root of the adult. It is probable that the root became bifurcated as the animal matured. Because there are two genera of ceratopsians ( Triceratops and Torosaurus ) in the Lance and Hell Creek formations, it is not possible to be more specific in the identification.

Figures

Figures 1-11. Fig. 1, Dromaeosauridae, tooth, UCM 39502. Fig. 2a-h, Sauromithoides inequalis: 20,, buccal view of hatchling left dentary, UCM 41666; c, lingual view; e, dorsal view; b, buccal view of left dentary, NMC 8540 (cast); d, lingual view; f, dorsal view; g, lateral view of hatchling basioccipital, UCM 43218; and h, ventral view. Fig. 3a-c, teeth of Pectinodon bakkeri: a, holotype, UCM 38445; b, paratype, UCM 38446; and c, paratype, UCMP 73098. Fig. 4, Pararıychodon lacustris, tooth, UCMP 124990. Fig. 5a, b, Tyrannosauridae: a as lateral view of UCMP 119853; and b, posterior view. Fig. 6, Theropoda, tooth, UCMP 124987. Fig. 7a, b, tooth of Aublysodon mirandus: a! lateral view of UCMP 124406; and b, posterior view. Fig. 8, Thescelosaurus sp., tooth, UCMP 124973. Fig. 9, Hadrosauridae, tooth, UCM 45060. Fig. 10, Ceratopsidae, tooth, UCM 45057. Fig. 11, Ankylosaurus magniventris, tooth, UCMP 124399. Heavy bars to left of specimens = 2 mm.