Anatomical Record, 2023

Tyrannosaurus has been an exemplar organism in feeding biomechanical ana- lyses. An adult Tyrannosaurus could exert a bone-splintering bite force, through expanded jaw muscles and a robust skull and teeth. While feeding function of adult Tyrannosaurus has been thoroughly studied, such analyses have yet to expand to other tyrannosauroids, especially early-diverging tyrannosauroids (Dilong, Proceratosaurus, and Yutyrannus). In our analysis, we broadly assessed the cranial and feeding performance of tyrannosauroids at varying body sizes. Our sample size included small (Proceratosaurus and Dilong), medium-sized (Terato- phoneus), and large (Tarbosaurus, Daspletosaurus, Gorgosaurus, and Yutyrannus) tyrannosauroids, and incorporation of tyrannosaurines at different ontogenetic stages (small juvenile Tarbosaurus, Raptorex, and mid-sized juvenile Tyrannosau- rus). We used jaw muscle force calculations and finite element analysis to compre- hend the cranial performance of our tyrannosauroids. Scaled subtemporal fenestrae areas and calculated jaw muscle forces show that broad-skulled tyranno- saurines (Tyrannosaurus, Daspletosaurus, juvenile Tyrannosaurus, and Raptorex) exhibited higher jaw muscle forces than other similarly sized tyrannosauroids (Gorgosaurus, Yutyrannus, and Proceratosaurus). The large proceratosaurid Yutyr- annus exhibited lower cranial stress than most adult tyrannosaurids. This suggests that cranial structural adaptations of large tyrannosaurids maintained adequate safety factors at greater bite force, but their robust crania did not notably decrease bone stress. Similarly, juvenile tyrannosaurines experienced greater cranial stress than similarly-sized earlier tyrannosauroids, consistent with greater adductor mus- cle forces in the juveniles, and with crania no more robust than in their small adult predecessors. As adult tyrannosauroid body size increased, so too did relative jaw muscle forces manifested even in juveniles of giant adults.

Acta Palaeontol Pol, 2010

M. 2010. New information on scavenging and selective feeding behaviour of tyrannosaurids. Acta Palaeontologica Polonica 55 (4): 627-634.

Proceedings of the National Academy of Sciences, 2013

Acta Palaeontologica Polonica, 2010

M. 2010. New information on scavenging and selective feeding behaviour of tyrannosaurids. Acta Palaeontologica Polonica 55 (4): 627-634.

PALAIOS, 2018

A recently discovered tyrannosaurid metatarsal IV (SWAU HRS13997) from the uppermost Cretaceous (Maastrichtian) Lance Formation is heavily marked with several long grooves on its cortical surface, concentrated on the bone's distal end. At least 10 separate grooves of varying width are present, which we interpret to be scores made by theropod teeth. In addition, the tooth ichnospecies Knethichnus parallelum is present at the end of the distal-most groove. Knethichnus parallelum is caused by denticles of a serrated tooth dragging along the surface of the bone. Through comparing the groove widths in the Knethichnus parallelum to denticle widths on Lance Formation theropod teeth, we conclude that the bite was from a Tyrannosaurus rex. The shape, location, and orientation of the scores suggest that they are feeding traces. The osteohistology of SWAU HRS13997 suggests that it came from a young animal, based on evidence that it was still rapidly growing at time of death. The tooth traces on SWAU HRS13997 are strong evidence for tyrannosaurid cannibalism-a large Tyrannosaurus feeding on a young Tyrannosaurus.

Science (New York, N.Y.), 2010

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2003. Skull structure and evolution in tyrannosaurid dinosaurs. Acta Palaeonto− logica Polonica 48 (2): 227–234. Tyrannosauridae can be subdivided into two distinct subfamilies—the Albertosaurinae and the Tyrannosaurinae. Previ− ously recognized subdivisions Aublysodontinae and Shanshanosaurinae are rejected because they are based on insuffi− cient material and juvenile specimens. Our results are based upon a phylogenetic analysis using PAUP program (Swofford 1999) of 77 skull characters and seven genera (Albertosaurus, Alioramus, Daspletosaurus, Gorgosaurus, Nanotyrannus, Tarbosaurus, and Tyrannosaurus); with Allosaurus as outgroup. Of the 77 characters used, more than half were parsimony informative. A single most parsimonious tree was obtained with the Tree Length being 88. The analysis of cranial characters and comparison of postcranial features reveal that Tarbosaurus bataar is not the sister taxon of Tyrannosaurus rex (contra Holtz 2001). Their similarities are partially due to the fact that both are extremely large ani− mals. Thus, Tarbosaurus should be considered a genus distinct from Tyrannosaurus.

Gaia, 1998

The frequency of tooth-marked bone in the Mesozoic is decidedly lower than the frequency found in the Cenozoic, although most of the previous work has focused on Cretaceous dinosaur faunas. This report describes two new examples of tooth-marked bone from the Jurassic Morrison Formation of western North America. The pubic foot of a specimen of Allosaurus from the Morrison Formation is missing a large section of its right side as the result of a single bite of a large theropod. Based on the size of the bite and known tooth size in large Morrison theropods, either Ceratosaurus or Torvosaurus can be responsible for the bite. Because of the large size of the Allosaurus and the location of the bite, it is suggested that the bite occurred during scavenging rather than during an attack by a predator. The pattern of tooth marks on this specimen are supportive of the hypothesis that predatory dinosaurs did not routinely chew the bones of their prey. Similarly, the tooth marks on a Camarasaurus ilium can be attributed to accidental contact with the teeth of a large predatory dinosaur as it removed the flesh of its prey, rather than the result of intentional chewing of the bone. As with mammalian predators, patterns of tooth-marked bone provide insight into the behavior of predatory dinosaurs. RESUMEN: La ocurrencia de huesos marcados por dientes en el Mesozoico es decididamente poca comparada con la del Cenozoico. La mayoria del estudio anterior ha enfocado en la fauna de dinosaurios del Cretácico. Este reporte describe dos ejemplos nuevos de huesos que provienen de la Formacion Morrison, Periodo Jurásico, en el occidente de Norte America. En el pie púbico de un Allosaurus de la Formacion Morrison le falta la mayor parte de los huesos del costado derecho, el resultado de una sola mordida de un gran terópodo. Usando el tamaño de la mordida y el tamaño conocido de los dientes de terópodos grandes de Morrison, puede que un Ceratosaurus o un Torvosaurus, fué quien dio la mordida. Dado el tamaño de Allosaurus y la localidad de la mordida, se sugiere que esta mordida ocurrió despúes de muerto en vez de por el ataque de un predador. El modelo de marcas de dientes de este espécimen soportan la hipótesis que los dinosaurios predadores usualmente no trituraban los huesos de sus presas. Igualmente las marcas de dientes en el ilium de un Camarasaurus se pueden atribuir a el contacto accidental de un gran dinosaurio predador según se comía la carne de la presa, en vez de mascar los huesos intencionalmente. Igual que con los predadores mamíferos, los huesos marcados por dientes nos dan un conocimiento más profundo de los hábitos de dinosaurios predadores.