ARTICLE Multivariate analysis of isolated tyrannosaurid teeth from the Danek Bonebed, Horseshoe Canyon Formation, Alberta, Canada 1 Angelica Torices, Miriam Reichel, and Philip J. Currie Abstract: A significant number of fossil remains of the hadrosaurid Edmontosaurus have been recovered from the Danek Bonebed (Horseshoe Canyon Formation, Upper Cretaceous, Alberta). Bones from theropod dinosaurs are scarce in this hadrosaur- dominated bonebed, but more than 60 tyrannosaurid theropod teeth have been found. The isolated tyrannosaurid teeth include juvenile and adult specimens, although the precise ontogenetic stage has not been determined. The use of multivariate analyses helps determine the variance of the sample and verifies the initial taxonomic affinities given to these teeth, showing their high potential as a useful tool to better discriminate tyrannosaurid teeth. It also provides an insight into the tyrannosaurid intra- specific variability in the Horseshoe Canyon Formation. Résumé : Un nombre significatif de restes fossiles d’hadrosauridés du genre Edmontosaurus ont été récupérés du lit a ` ossements de Danek (Formation de Horseshoe Canyon, Crétacé supérieur, Alberta). Si les os de dinosaures théropodes sont rares dans ce lit où dominent les ossements d’hadrosaure, plus de 60 dents de théropode tyrannosauridé y ont été trouvées. Ces dents isolées de tyrannosauridé comprennent des spécimens provenant d’individus juvéniles et adultes, bien que le stade ontogénétique précis n’ait pas été déterminé. L’utilisation d’analyses multivariées aide a ` déterminer la variance de l’échantillon et permet de vérifier les affinités taxinomiques initiales attribuées a ` ces dents, démontrant le potentiel de ces analyses pour mieux discriminer les dents de tyrannosauridé. Elle fournit également de l’information sur la variabilité intraspécifique des tyrannosauridés dans la Formation de Horseshoe Canyon. [Traduit par la Rédaction] Introduction In the Upper Cretaceous Danek Bonebed, nearly 95% of the fossils are from the hadrosaur Edmontosaurus. Most of the re- maining 5% of the fossils are tyrannosaurid specimens, although there are single elements of a ceratopsian, an ornithomimid, Saurornitholestes, and Troodon. It is significant that the second most abundant taxon at the site is Tyrannosauridae. The evidence sug- gests that the Edmontosaurus died en masse and subsequently were scavenged by tyrannosaurids and small theropods. Bite marks have been found abundantly in hadrosaur bones associated to theropod shed teeth (Arbour and Bramble 2013). Most of the tyrannosaurid remains are teeth that were prob- ably shed when the theropods were feeding on the corpses of Edmontosaurus. Of the isolated teeth, 56% appeared in Quarry 1, 24% in Quarry 2, and 19% in Quarry 3. This difference may be due to the fact that not all quarries were excavated at the same time, with Quarry 1 being the oldest. A tyrannosaurid maxilla, dentary, and pterygoid have also been recovered, but they may represent a single individual that died alongside Edmontosaurus (Arbour and Bramble 2013). Also, all the isolated tyrannosaurid teeth found in the site are shed teeth, without a root, having been removed from the skull of the dinosaur during life. According to a recent study by Peterson et al. (2014), shed theropod teeth do not transport very far due to their morphology and thus would remain as lag. This affirmation, along with the presence of bite marks, would support that the high number of isolated tyrannosaurid teeth found in the site would be the consequence of scavenging of these carnivorous dinosaurs over the carcasses of Edmontosaurus and not a result of an accumulation due to transport. Isolated teeth are the most abundant remains of theropods found in all Mesozoic sediments worldwide. Although not as spectacular as complete skeletons, teeth are sometimes the only evidence of these animals at certain sites and are important to understand the palaeo- ecology and palaeodiversity of these localities, and the evolution of palaeocommunities (Currie et al. 1990; Baszio 1997; Fiorillo and Gangloff 2001; Sankey et al. 2002; Samman et al. 2005; Smith 2005; Buckley et al. 2010; Larson and Currie 2013; Torices et al. 2013a). The variability of tyrannosaurid teeth from the Danek Bonebed and tyrannosaurid intraspecific variability in the Horseshoe Canyon Formation are examined in this study. The data from the isolated teeth are compared with those from the maxilla (TMP 1989.17.53) that was found in the bonebed to determine whether all the teeth belong to the same taxon and to examine the vari- ance of the whole sample. Multivariate analysis was used to deter- mine if Albertosaurus teeth can be distinguished from those of Daspletosaurus, as the latter taxon should also be present in the Horseshoe Canyon Formation (Currie 2003). The Danek Bonebed theropod teeth were compared with Albertosaurus teeth from Dry Received 5 April 2014. Accepted 6 September 2014. Paper handled by Associate Editor Michael Ryan. A. Torices. Department of Biological Sciences, University of Alberta, CW 405 Biological Sciences Centre, Edmonton, AB T6G 2E9, Canada; Departamento de Paleontología, Facultad de Geología, Universidad Complutense de Madrid, 28040, Madrid, Spain. M. Reichel and P.J. Currie. Department of Biological Sciences, University of Alberta, CW 405 Biological Sciences Centre, Edmonton, AB T6G 2E9, Canada. Corresponding author: Angelica Torices (e-mail: torices@ualberta.ca). 1 This article is part of a Special Issue entitled “The Danek Edmontosaurus Bonebed: new insights on the systematics, biogeography, and palaeoecology of Late Cretaceous dinosaur communities”. 1045 Can. J. Earth Sci. 51: 1045–1051 (2014) dx.doi.org/10.1139/cjes-2014-0072 Published at www.nrcresearchpress.com/cjes on 15 December 2014. Can. J. Earth Sci. Downloaded from www.nrcresearchpress.com by University of Alberta on 12/15/14 For personal use only.