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Tyrannosauroid dinosaurs from the Aguja Formation (Upper Cretaceous) of Big Bend National Park, Texas

Published online by Cambridge University Press:  23 September 2013

Thomas M. Lehman
Department of Geosciences, Texas Tech University, Lubbock, TX 79409USA.
Steven L. Wick
Division of Science and Resource Management, Big Bend National Park, TX 79834USA.


Rare remains of tyrannosauroid dinosaurs from the Aguja Formation in West Texas indicate the presence here of a relatively gracile species, comparable in form and adult size to Appalachiosaurus or subadult albertosaurines, Gorgosaurus and Albertosaurus. Histologic analysis of one of the specimens indicates that the Aguja tyrannosaur attained an adult size substantially smaller than adult albertosaurines (700 kg, 6·5 m body length). The frontal bone is narrow with a wide orbital slot and a bipartite joint for the postorbital, features thought to be diagnostic of Albertosaurinae; but there is a tall sagittal crest and reduced parietal wedge separating the frontals on the midline, features thought to be diagnostic of Tyrannosaurinae. The tall sagittal crest may be a synapomorphy of Tyrannosaurinae, and the Aguja tyrannosaur is herein referred to that clade. However, the unique combination of character states exhibited by the frontal prevents confident attribution to any known species. The Aguja tyrannosaur provides further evidence that North American Campanian tyrannosauroids were remarkably diverse for such large predators, and that each species was apparently endemic to a relatively small geographic province.

Copyright © The Royal Society of Edinburgh 2013 

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5. References

Bakker, R. T., Williams, M. & Currie, P. 1988. Nanotyrannus, a new genus of pygmy tyrannosaur from the latest Cretaceous of Montana. Hunteria 1 (5), 26 pp.Google Scholar
Befus, K. S., Hanson, R. E., Lehman, T. M. & Griffin, W. R. 2008. Cretaceous basaltic phreatomagmatic volcanism in West Texas: maar complex at Pena Mountain, Big Bend National Park. Journal of Volcanology and Geothermal Research 173 (3–4), 245–64.Google Scholar
Brochu, C. A. 2003. Osteology of Tyrannosaurus rex: insights from a nearly complete skeleton and high-resolution computed tomographic analysis of the skull. Journal of Vertebrate Paleontology Memoir 7, 1138.Google Scholar
Brusatte, S. L., Carr, T. D., Erickson, G. M., Bever, G. S. & Norell, M. A. 2009. A long-snouted, multihorned tyrannosaurid from the Late Cretaceous of Mongolia. Proceedings of the National Academy of Sciences 106 (41), 17261–66.Google Scholar
Brusatte, S. L., Benson, R. B. & Norell, M. A. 2011. The anatomy of Dryptosaurus aquilunguis (Dinosauria: Theropoda) and a review of its tyrannosauroid affinities. American Museum Novitates 3717, 153.Google Scholar
Buckley, L. G., Larson, D. W., Reichel, M. & Samman, T. 2010. Quantifying tooth variation within a single population of Albertosaurus sarcophagus (Theropoda: Tyrannosauridae) and implications for identifying isolated teeth of tyrannosaurids. Canadian Journal of Earth Science 47 (9), 1227–51.Google Scholar
Carpenter, K., Russell, D., Baird, D. & Denton, R. 1997. Redescription of the holotype of Dryptosaurus aquilunguis (Dinosauria: Theropoda) from the Upper Cretaceous of New Jersey. Journal of Vertebrate Paleontology 17 (3), 561–73.Google Scholar
Carr, T. D. 1999. Craniofacial ontogeny in Tyrannosauridae (Dinosauria, Coelurosauria). Journal of Vertebrate Paleontology 19 (3), 497520.Google Scholar
Carr, T. D., Williamson, T. E. & Schwimmer, D. R. 2005. A new genus and species of tyrannosauroid from the Late Cretaceous (Middle Campanian) Demopolis Formation of Alabama. Journal of Vertebrate Paleontology 25 (1), 119–43.Google Scholar
Carr, T. D., Williamson, T. E., Britt, B. B. & Stadtman, K. 2011. Evidence for high taxonomic and morphologic tyrannosauroid diversity in the Late Cretaceous (Late Campanian) of the American Southwest and a new short-skulled tyrannosaurid from the Kaiparowits Formation of Utah. Naturwissenschaften 98 (3), 241–46.Google Scholar
Carr, T. D. & Williamson, T. E. 2000. A review of Tyrannosauridae (Dinosauria, Coelurosauria) from New Mexico. In Lucas, S. & Heckert, A. (eds.) Dinosaurs of New Mexico. New Mexico Museum of Natural History and Science Bulletin 17, 113–45.Google Scholar
Carr, T. D. & Williamson, T. E. 2004. Diversity of late Maastrichtian Tyrannosauridae (Dinosauria: Theropoda) from western North America. Zoological Journal of the Linnean Society 142, 479523.Google Scholar
Carr, T. D. & Williamson, T. E. 2010. Bistahieversor sealeyi, gen. et sp. nov., a new tyrannosauroid from New Mexico and the origin of deep snouts in Tyrannosauroidea. Journal of Vertebrate Paleontology 30 (1), 116.Google Scholar
Currie, P. J. 1987. Theropods of the Judith River Formation of Dinosaur Provincial Park, Alberta, Canada. In Currie, P. J. & Koster, E. H. (eds) Fourth Symposium on Mesozoic Terrestrial Ecosystems, Tyrrell Museum of Palaeontology Occasional paper of the 3. Drumheller, Alberta. 5260.Google Scholar
Currie, P. J. 1998. Possible evidence for gregarious behavior in tyrannosaurids. Gaia 15, 271–77.Google Scholar
Currie, P. J. 2003a. Allometric growth in tyrannosaurids (Dinosauria: Theropoda) from the Upper Cretaceous of North America and Asia. Canadian Journal of Earth Sciences 40 (4), 651–65.Google Scholar
Currie, P. J. 2003b. Cranial anatomy of tyrannosaurid dinosaurs from the Late Cretaceous of Alberta, Canada. Acta Palaeontologica Polonica 48 (2), 191226.Google Scholar
Currie, P. J., Hurum, J. H. & Sabath, K. 2003. Skull structure and evolution in tyrannosaurid dinosaurs. Acta Palaeontologica Polonica 48 (2), 227–34.Google Scholar
Erickson, G. M., Makovicky, P. J., Currie, P. J., Norell, M. A., Yerby, S. A. & Brochu, C. A. 2004. Gigantism and comparative life-history parameters of tyrannosaurid dinosaurs. Nature 430 (7001), 772–75.Google Scholar
Erickson, G. M. & Olson, K. H. 1996. Bite marks attributable to Tyrannosaurus rex: preliminary description and implications. Journal of Vertebrate Paleontology 16 (1), 175–78.Google Scholar
Farlow, J. O., Brinkman, D. L., Abler, W. L. & Currie, P. J. 1991. Size, shape, and serration density of theropod dinosaur lateral teeth. Modern Geology 16 (1–2), 161–98.Google Scholar
Farlow, J. O. & Pianka, E. R. 2002. Body size overlap, habitat partitioning and living space requirements of terrestrial vertebrate predators: implications for the paleoecology of large theropod dinosaurs. Historical Biology 16 (1), 2140.Google Scholar
Holtz, T. R. Jr. 1995. The arctometatarsalian pes, an unusual structure of the metatarsus of Cretaceous Theropoda (Dinosauria: Saurischia). Journal of Vertebrate Paleontology 14 (4), 480519.Google Scholar
Holtz, T. R. Jr. 2001. The phylogeny and taxonomy of the Tyrannosauridae. In Tanke, D. & Carpenter, K. (eds) Mesozoic Vertebrate Life, 6483. Bloomington: Indiana University Press.Google Scholar
Lambe, L. M. 1917. The Cretaceous theropodous dinosaur Gorgosaurus. Geological Survey of Canada Memoir 100, 84 pp.Google Scholar
Lehman, T. M. 1985. Stratigraphy, sedimentology, and paleontology of Upper Cretaceous (Campanian-Maastrichtian) sedimentary rocks in Trans-Pecos Texas. Unpublished Ph.D. Dissertation, University of Texas at Austin. 300 pp.Google Scholar
Lehman, T. M. 1997. Campanian dinosaur biogeography in the western interior of North America. In Wolberg, D. & Stump, E. (eds.), Dinofest International, proceedings of a symposium sponsored by Arizona State University, 223–40. Philadelphia Academy of Natural Sciences, Special Publication.Google Scholar
Lehman, T. M. & Busbey, A. B. 2007. Big Bend Field Trip Field Guide. Society of Vertebrate Paleontology, Fall 2007 Field Trip. 69 pp.Google Scholar
Lehman, T. M. & Carpenter, K. 1990. A partial skeleton of the tyrannosaurid dinosaur Aublysodon from the Upper Cretaceous of New Mexico. Journal of Paleontology 64 (6), 1026–32.Google Scholar
Lehman, T. M. & Woodward, H. N. 2008. Modeling growth rates for sauropod dinosaurs. Paleobiology 34 (2), 264–81.Google Scholar
Marsh, O. C. 1881. Classification of the Dinosauria. American Journal of Science (series 3) 21, 417–23.Google Scholar
Molnar, R. E. 1978. A new theropod dinosaur from the Upper Cretaceous of central Montana. Journal of Paleontology 52 (1), 7382.Google Scholar
Molnar, R. E. 1980. An albertosaur from the Hell Creek Formation of Montana. Journal of Paleontology 54 (1), 102–08.Google Scholar
Molnar, R. E. 1991. The cranial morphology of Tyrannosaurus rex. Palaeontographica A 217, 137176.Google Scholar
Molnar, R. E. & Carpenter, K. 1989. The Jordan theropod (Maastrichtian, Montana, U.S.A.) referred to the genus Aublysodon. Geobios 22 (4), 445–54.Google Scholar
Olshevsky, G. 1995. The origin and evolution of the tyrannosaurids. Kyoryugaku Saizensen (Dino Frontime) 9, 92119; 10, 75–99. [In Japanese with English translation.]Google Scholar
Osborn, H. F. 1906. Tyrannosaurus, Upper Cretaceous carnivorous dinosaur (second communication). American Museum of Natural History Bulletin 22, 281–96.Google Scholar
Parks, W. A. 1928. Albertosaurus arctunguis, a new species of theropodous dinosaur from the Edmonton Formation of Alberta. University of Toronto Geological Series 25. 42 pp.Google Scholar
Paul, G. S. 1988. Predatory Dinosaurs of the World. New York: Simon and Schuster.Google Scholar
Rowe, T., Cifelli, R. L., Lehman, T. M. & Weil, A. 1992. The Campanian Terlingua local fauna, with a summary of other vertebrates from the Aguja Formation, Trans-Pecos Texas. Journal of Vertebrate Paleontology 12 (4), 472–93.Google Scholar
Russell, D. A. 1970. Tyrannosaurs from the Late Cretaceous of western, Canada. Canadian National Museum of Natural Sciences, Publications in Paleontology 1, 134.Google Scholar
Samman, T., Powell, G. L., Currie, P. J. & Hills, L. V. 2005. Morphometry of the teeth of western North American tyrannosaurids and its applicability to quantitative classification. Acta Palaeontologica Polonica 50 (4), 757–76.Google Scholar
Sankey, J. T. 2001. Late Campanian southern dinosaurs, Aguja Formation, Big Bend, Texas. Journal of Paleontology 75 (1), 208–15.Google Scholar
Schubert, B. W. & Ungar, P. S. 2005. Wear facets and enamel spalling in tyrannosaurid dinosaurs. Acta Palaeontologica Polonica 50 (1), 9399.Google Scholar
Schwimmer, D. R. 2002. King of the Crocodylians. Bloomington: Indiana University Press. 220 pp.Google Scholar
Seeley, H. G. 1887. On the classification of the fossil animals commonly named Dinosauria. Proceedings of the Royal Society, London 43 (258–265), 165–71.Google Scholar
Sereno, P. C., Tan, L., Brusatte, S. L., Kriegstein, H. J., Zhao, X. & Cloward, K. 2009. Tyrannosaurid skeletal design first evolved at small body size. Science 236 (5951), 418–22.CrossRefGoogle Scholar
Sereno, P. C. & Brusatte, S. L. 2009. Comparative assessment of tyrannosaurid interrelationships. Journal of Systematic Palaeontology 7 (4), 455–70.Google Scholar
Smith, J. B., Vann, D. R. & Dodson, P. 2005. Dental morphology and variation in theropod dinosaurs: implications for the taxomomic identification of isolated teeth. The Anatomical Record 285A (2), 699736.Google Scholar
Standhardt, B. R. 1986. Vertebrate paleontology of the Cretaceous/Tertiary transition of Big Bend National Park, Texas. Ph.D. Dissertation, Louisiana State University, Baton Rouge. 299 pp.Google Scholar
Udden, J. A. 1907. A sketch of the geology of the Chisos country. University of Texas Bulletin 93, 101 pp.Google Scholar
Waggoner, K. J. 2006. Sutural form and shell morphology of Placenticeras, and systematic descriptions of Late Cretaceous ammonites from the Big Bend region, Texas. Unpublished Ph.D. Dissertation, Texas Tech University, Lubbock, Texas. 398 pp.Google Scholar
Wagner, J. R. & Lehman, T. M. 2009. An enigmatic new lambeosaurine hadrosaur (Reptilia: Dinosauria) from the upper shale member of the Campanian Aguja Formation of Trans-Pecos Texas. Journal of Vertebrate Paleontology 29 (2), 605–11.Google Scholar