Testing Utility

Developing an Assessment to Evaluate Tyrannosaurus rex Forelimb Use Cases





Tyrannosaurs, Forelimbs, Use Cases, Biomechanics, Use Tests


Tyrannosaurus rex is infamous for its large body size and seemingly mismatched forelimbs, which are extremely small relative to body size. Since its first description by Osborn in 1905, the diminutive size of this attribute has fueled an arms race of sorts wherein specialists have advanced numerous theories seeking to prove a seemingly single-track use or non-use for the arms. While the overall debate on the evolutionary processes behind the small limb size are not addressed here, previous functional theories are reviewed within a functionalist perspective. This paper contends that Tyrannosaurus rex would have used its limbs for whatever purposes possible and that selecting one function to the exclusion of others is not a realistic approach to understanding the lifeways of the Tyrant King. Rather, a functionality assessment is suggested and tested using existing theories with the aim of providing a tool to assess future use case theories.


Download data is not yet available.


Agnolin, F. L., & Chiarelli, P. (2010). The position of the claws in Noasauridae (Dinosauria: Abelisauroidea) and its implications for abelisauroid manus evolution. Paläontologische Zeitschrift, 84(2), 293-300. http://dx.doi.org/10.1007%2Fs12542-009-0044-2

Benton, M.J., & Harper, D.A.T. (2013). Introduction to paleobiology and the fossil record. Wiley-Blackwell.

Bonaparte, J.F., Novas, F.E., & Coria, R.A. (1990). Carnotaurus sastrei Bonaparte, the horned, lightly built carnosaur from the Middle Cretaceous of Patagonia. Contributions in Science, 416, 1–41.

Brochu, C. R. (2003). Osteology of Tyrannosaurus rex: insights from a nearly complete skeleton and high-resolution computed tomographic analysis of the skull. Society of Vertebrate Paleontology Memoirs, 22(4), 1–138. https://doi.org/10.1080/02724634.2003.10010947

Burch, S., & Carrano, M. (2012). An articulated pectoral girdle and forelimb of the abelisaurid theropod Majungasaurus crenatissimus from the Late Cretaceous of Madagascar. Journal of Vertebrate Paleontology, 32 (1), 1-16. https://doi.org/10.1080/02724634.2012.622027

Carpenter, K. (2002). Forelimb biomechanics of nonavian theropod dinosaurs in predation. Senckenbergiana lethaea, 82, 59–75. https://doi.org/10.1007/BF03043773

Carpenter, K., & Smith, M. (2001). Forelimb osteology and biomechanics of Tyrannosaurus rex. In D. Tanke, & K. Carpenter (Eds.), Mesozoic Vertebrate Life (pp. 90-116). Indiana, USA: Indiana University Press.

Carpenter, K. (1998). Evidence of predatory behavior by carnivorous dinosaurs, Gaia, 15, 135-144.

Fastovsky, D.E., & Weishampel, D.B. (2005). The evolution and extinction of the dinosaurs. Cambridge University Press.

Gould, S.J. (2010). The panda's thumb: More reflections in natural history. New York: W.W. Norton & Company.

Hanna, R. (2003). Dinosaurs got hurt too. In G. Paul (Ed.), The Scientific American Book of Dinosaurs (pp. 119-126). New York: St. Martin’s Press.

Holtz, T. (2007). Dinosaurs: The most complete, up-to-date encyclopedia for dinosaur lovers of all ages. New York: Random House.

Hone, D. (2016). The tyrannosaur chronicles: The biology of the tyrant dinosaurs. London, UK: Bloomsbury Publishing.

Horner, J. R., & Lessem, D. (1993). The complete T. Rex. New York: Simon & Schuster.

Hutchinson, J., Bates, K., Molnar, J., Allen, V., & Makovicky, P. (2011). A computational analysis of limb and body dimensions in Tyrannosaurus rex with implications for locomotion, ontogeny, and growth. PLoS ONE, 6(10), e26037. https://doi.org/10.1371/journal.pone.0097055

Krauss, D., & Robinson, J. (2013). The biomechanics of a plausible hunting strategy for Tyrannosaurus rex. In M. Parrish, R. Molnar, P. Currie, & E. Koppelhus (Eds.), Tyrannosaurid paleobiology (pp. 251-264). Indiana, USA: Indiana University Press.

Lacovara, K. (2017). Why dinosaurs matter. New YorkSimon and Schuster.

Lipkin, C., & Carpenter, K. (2008). Looking again at the forelimb of Tyrannosaurus rex. In P. Larson, & K. Carpenter (Eds.), Tyrannosaurus rex, The Tyrant King (pp. 167-190). Indiana, USA: Indiana University Press.

Lockley, M., Kukihara, R., & Mitchell, L. (2008). Why Tyrannosaurus rex had puny arms: An integral morphodynamic solution to a simple puzzle in theropod paleobiology In P. Larson and K. Carpenter (Eds.), Tyrannosaurus rex, the Tyrant King (pp. 131-166). Indiana, USA: Indiana University Press.

Mattison, R., & Griffin, E. (1989). Limb use and disuse in ratites and tyrannosaurids. Journal of Vertebrate Paleontology, 13(3), 49A.

Newman, B. (1970). Stance and gait in the flesh-eating Tyrannosaurus. Biological Journal of the Linnaean Society, 2(2), 119–123. https://doi.org/10.1111/j.1095-8312.1970.tb01707.x

Osborn, H.F., & Brown, B. (1906). Tyrannosaurus, Upper Cretaceous carnivorous dinosaur. Bulletin of the American Museum of Natural History, 22(16), 281–296.

Paul, G. (1988). Predatory dinosaurs of the world. New York: Simon and Schuster.

Pickrell, J. (2017). T. rex’s tiny arms may have been vicious weapons. Retrieved from https://news.nationalgeographic.com/2017/11/tyrannosaurus-rex-arms-weapons-paleontology-science/

Reichel, M., & Hans-Dieter, S. (2012). The variation of angles between anterior and posterior carinae of tyrannosaurid teeth. Canadian Journal of Earth Sciences, 49(3), 477–491. https://doi.org/10.1139/e11-068

Rothschild, B. (2013). Clawing their way to the top: Tyrannosaurid pathology and lifestyle. In M. Parrish, R. Molnar, P. Currie, & E. Koppelhus (Eds.). Tyrannosaurid paleobiology (pp. 211-222). Indiana, USA: Indiana University Press.

Ruiz, J., Torices, A., Serrano, H., & López, V. (2011). The hand structure of Carnotaurus sastrei (Theropoda, Abelisauridae): implications for hand diversity and evolution in abelisaurids. Palaeontology, 54(6), 1271–1277. https://doi.org/10.1111/j.1475-4983.2011.01091.x

Senter, P. (2010). Vestigial skeletal structures in dinosaurs. Journal of Zoology, 280(4), 60–71. https://doi.org/10.1111/j.1469-7998.2009.00640.x

Stanley, S. (2017). Evidence that the arms of Tyrannosaurus rex were not functionless but adapted for vicious slashing. Geological Society of America Abstracts with Programs, 49(6). https://doi.org/10.1130/abs/2017AM-297346

Wang, C., & Cai, D. (2016). Hand tool handle design based on hand measurements. MATEC Web of Conferences, 119, 01044. Retrieved from https://www.matec-conferences.org/articles/matecconf/pdf/2017/33/matecconf_imeti2017_01044.pdf

Weishampel, D.B. (1995). Fossils, function, and phylogeny. In J.J. Thomason (Ed.), Functional Morphology in Vertebrate Paleontology (pp. 34-54). Cambridge: Cambridge University Press.




How to Cite

Arp, D. (2020). Testing Utility: Developing an Assessment to Evaluate Tyrannosaurus rex Forelimb Use Cases. Biosis: Biological Systems, 1(3), 102–108. https://doi.org/10.37819/biosis.001.03.0060