TYRANNOSAURIDAE, Osborn, 1906

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 : 130

Family TYRANNOSAURIDAE

Fig. 5 a, b

Material: Tooth, UCMP 119853 (UCMP-V72207) H 8 mm, W 4 mm .

Discussion: The D-shaped cross section, position of the serrations, and robustness indicate a first right maxillary tooth ( Fig. 5 a, b ). The D-shaped cross-section gives the tooth an incisiform appearance, and is known only in the premaxillary teeth and first maxillary teeth of tyrannosaurids and in the teeth of Aublysodon mirandus (see below). In all other theropods, the premaxillary teeth become progressively more asymmetrical toward the front of the tooth row as the anterior serrations assume a more medial position (but this does not result in a D-shaped cross section and incisiform tooth; see Lambe, 1917 and Ostrom, 1969). UCMP 119853 is so heavily worn that the anterior serrations are almost obliterated.

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.