HETERODONTY IN TYRANNOSAURUS REX: IMPLICATIONS FOR THE TAXONOMIC AND SYSTEMATIC UTILITY OF THEROPOD DENTITIONS

By Joshua B. Smith. 2005

93 citations recorded by the source corpus.

Abstract Tyrannosaurus rex possesses a heterodont dentition composed of three classes (premaxillary, maxillary, and dentary) and several sets. The maxilla contains mesial and distal sets and the dentary contains first dentary tooth (d1), mesial, and distal sets. Teeth were described with four size and two shape variables and several variables describing crown curvature and denticle size. The premaxillary teeth are derived structures with labiolingually oriented long axes, moderate mesial curvature, and mesiolingually and distolingually placed carinae that extend down the lingual faces. The mesial maxillary crowns are large, basally rounded, and moderately curved with mesiodistally oriented long axes. The mesial carinae begin at the apices and curve lingually to about the midcrown point and the distal carinae begin at the apices and extend down the labial sides of the distal faces. The distal maxillary crowns are larger than the premaxillary and smaller than the mesial maxillary and all but the most distal dentary teeth. They have labiolingually oriented long axes and have narrower basal widths than lengths. The carinae roughly define the mesiodistal axes of the crowns. The first dentary tooth is similar to those of the premaxilla. The mesial dentary teeth are similar to the mesial maxillary teeth and the distal dentary teeth are similar to those in the distal maxilla. This examination revealed that several putative systematic characters related to size and shape can be discerned from T. rex teeth, suggesting that useful dental characters may be more common within the Theropoda than has generally been presumed.

Subfields: Global and Planetary Change, Paleontology

View Paper: https://www.semanticscholar.org/paper/f69736d2258cc87dccbe4232fa8239c0e7fdcaac

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Citations in the corpus

The Dentition of Megalosaurid Theropods (2014, methodology): “…(2005) and Smith et al. (2005) and performed a discriminant analysis (or canonical variate analysis, CVA) using PAST3 (Hammer et al. 2001) on numerical data collected by Smith (2005) and Smith et al. (2005), and updated by Smith and Lamanna (2006), Smith and Dalla Vecchia (2006), and Smith (2007).”
The distribution of dental features in non-avian theropod dinosaurs: Taxonomic potential, degree of homoplasy, and major evolutionary trends (2019, background): “In many tyrannosauroids, the lingual surface of mesial teeth is concave, biconcave or planar, but in Ornitholestes and some tyrannosaurids like Tarbosaurus and Tyrannosaurus, the mesial margin is strongly convex, giving an oval-shaped to the crown base’s cross-section (Smith, 2005, figure 8A).”
A Proposed Terminology of Theropod Teeth (Dinosauria, Saurischia) (2015, background): “…America (e.g., Currie, 1987; Currie et al., 1990; Fiorillo and Currie, 1994; Baszio, 1997; Fiorillo and Gangloff, 2001; Sankey et al., 2002; Smith, 2005, 2007; Fanti and Therrien, 2007; Brinkman, 2008; Longrich, 2008; Sankey, 2008; Buckley, 2009; Larson et al., 2010; Gianechini et al.,…”
Komodo monitor (Varanus komodoensis) feeding behavior and dental function reflected through tooth marks on bone surfaces, and the application to ziphodont paleobiology (2009, background): “Lastly, the concept that ziphodont dentition is strictly homodont is now believed to be ‘‘too simple’’ (Smith 2005: p. 867).”
The Osteology of Alioramus, A Gracile and Long-Snouted Tyrannosaurid (Dinosauria: Theropoda) from the Late Cretaceous of Mongolia (2012, background): “CBL 5 crown base length; CBW 5 crown base width; CH 5 crown height (see Smith and Dodson, 2003; Smith, 2006).”
Osteology of Cryolophosaurus ellioti (Dinosauria: Theropoda) from the Early Jurassic of Antarctica and implications for early theropod evolution (2007, background): “The ventral orientation of the paroccipital processes may also aid in obscuring these foramina, as it appears to do in Ceratosaurus (Sanders & Smith, 2005).”