Search

The isolated adult teeth of titanosaurian sauropods from the Upper Cretaceous Bissekty Formation at Dzharakuduk, Uzbekistan, differ little in overall structure but show considerable variation in enamel sculpturing and wear patterns. The crown shape of unworn juvenile teeth ranges from lanceolate to conical. Most specimens have enamel texture resembling crumpled paper or completely smooth enamel. Longitudinal grooves along the mesial and distal edges are present on only a few tooth crowns and might be developed on both the labial and lingual sides. Among 252 worn tooth crowns there are eight variants of wear patterns, all possible combinations of 0–2 apical and 0–2 lateral wear facets. The most common is wear pattern A1L0 (one apical facet, no lateral facets; 62.7%). The next most common variant has two apical and no lateral facets (A2L0, 12.3%). These apical wear facets include the primary wear facets, which are produced by an opposing functional tooth, and secondary wear facets, which are produced by a replacing upper tooth coming into contact with the functional lower tooth at a late wear stage. The relative abundance of tooth crowns with two apical wear facets possibly suggests incipient development of a tooth battery in the Bissekty titanosaur. [ABSTRACT FROM PUBLISHER]

Abstract: There exists a major gap in the fossil record of tyrannosauroid theropod dinosaurs spanning the early part of the Late Cretaceous. We report on skeletal remains referable to Tyrannosauroidea indet. from the Turonian Bissekty Formation at Dzharakuduk in the central Kyzylkum Desert of Uzbekistan. Phylogenetic analysis of the hypodigm places the Bissekty tyrannosauroid as a non-tyrannosaurid tyrannosauroid more basal than the Campanian tyrannosauroids Appalachiosaurus and Bistahieversor from North America. [Copyright &y& Elsevier]