Skip to main content
- Research Article
- Published:
The Tyrant Lizard King, Queen and Emperor: Multiple Lines of Morphological and Stratigraphic Evidence Support Subtle Evolution and Probable Speciation Within the North American Genus Tyrannosaurus
Evolutionary Biology (2022)
Abstract
All skeletal specimens of the North American dinosaur Tyrannosaurus and a number of trace fossils have been attributed to the single species: T. rex. Although an unusual degree of variation in skeletal robustness among specimens and variability in anterior dentary tooth form have been noted, the possibility of sibling species within the genus Tyrannosaurus has never been tested in depth in both anatomical and stratigraphic terms. New analysis, based on a dataset of over three dozen specimens, finds that Tyrannosaurus specimens exhibit such a remarkable degree of proportional variations, distributed at different stratigraphic levels, that the pattern favors multiple species at least partly separated by time; ontogenetic and sexual causes being less consistent with the data. Variation in dentary incisiform counts correlate with skeletal robusticity and also appear to change over time. Based on the current evidence, three morphotypes are demonstrated, and two additional species of Tyrannosaurus are diagnosed and named. One robust species with two small incisors in each dentary appears to have been present initially, followed by two contemporaneous species (one robust and another gracile) both of which had one small incisor in each dentary, suggesting both anagenesis and cladogenesis occurred. The geological/geographic forces underlying the evolution of multiple Tyrannosaurus species are examined. A discussion of the issues involving the recognition and designation of multiple morphotypes/species within dinosaur genera is included.
This is a preview of subscription content, access via your institution.
Data Availability
Not applicable.
Code Availability
Not applicable.
References
Bijiert, P. A., Soest, A. J., & Schulp, A. S. (2021). Natural frequency method: Estimating the preferred walking speed of Tyrannosaurus rex based on tail natural frequency. Royal Society Open Science, 8, 201441.
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, 22(Memoir 7), 1–138.
Brown, C. M., Boyd, C. A., & Russell, P. (2011). A new basal ornithopod dinosaur (Frenchman Formation), and implications for late Maastrichtian ornithischian diversity in North America. Zoological Journal, 163, 1157–1198.
Brusatte, S. L., & Carr, T. D. (2016). The phylogeny and evolutionary history of tyrannosaurid dinosaurs. Scientific Reports, 6, 20252.
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 of USA, 106, 17261–17266.
Burger, J., Rosnedahl, W., Loreille, O., Hemmer, H., Eriksson, T., Gotherstrom, A., et al. (2004). Molecular phylogeny of the extinct cave lion Panthera leo spelaea. Molecular Phylogenetics and Evolution, 30, 841–849.
Caneer, T., Molkestad, T., & Lucas, S. G. (2021). Tracks in the Upper Cretaceous of the Raton Basin possibly show tyrannosaurid rising from a prone position. New Mexico Museum of Natural History and Science Bulletin, 82, 29–37.
Carabajal, A. P., Currie, P. J., Dudgeon, T. W., Larsson, H. C. E., & Miyashita, T. (2021). Two braincases of Daspletosaurus: Anatomy and comparison. Canadian Journal of Earth Sciences, 58, 885–910.
Carpenter, K. (1990). Variation in Tyrannosaurus rex. In K. Carpenter & P. J. Currie (Eds.), Dinosaur systematics: Perspectives and approaches (pp. 141–145). Cambridge University Press.
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 University Press.
Carr, T. D. (2020). A high-resolution growth series of Tyrannosaurus rex obtained from multiple lines of evidence. PeerJ, 8, e9192.
Carr, T. D., Varrichio, D. J., Sedlmayr, J. C., Roberts, E. M., & Moore, J. R. (2017). A new tyrannosaur with evidence for anagenesis and crocodile-like facial sensory system. Scientific Reports, 7, 44942.
Carr, T. D., & Williamson, T. E. (2004). Diversity of Late Maastrichtian Tyrannosauridae from western North America. Zoological Journal of the Linnean Society, 142, 479–523.
Carrano, M. T., & Hutchinson, J. R. (2002). Pelvic and hindlimb musculature of Tyrannosaurus rex. Journal of Morphology, 253, 207–228.
Catuneanu, O., Sweet, A. R., & Miall, A. D. (2000). Reciprocal stratigraphy of the Campanian-Paleocene Western Interior of North America. Sedimentary Geology, 134, 235–255.
Chin, K., Tokaryk, T. T., Erickson, G. M., & Calk, L. C. (1998). A king-sized theropod coprolite. Nature, 393, 680–682.
Cost, I. N., Middleton, K. M., Sellers, K. C., Echols, M. S., Witmer, L. M., Davis, J. L., et al. (2019). Palatal biomechanics and its significance for cranial kinesis in Tyrannosaurus rex. Anatomical Record, 303, 999–1017.
Currie, P. J. (2003). Allometric growth in tyrannosaurids from the Upper Cretaceous of North America and Asia. Canadian Journal of Earth Sciences, 40, 651–665.
Dean, C. D., Chiarenza, A. A., & Maindment, S. C. R. (2020). Formation binning: A new method for increased temporal resolution in regional studies, applied to the Late Cretaceous dinosaur fossil record of North America. Palaeontology, 63, 881–901.
DePalma, R. A., Burnham, D. A., Martin, L. D., Rothschild, B. M., & Larson, P. L. (2013). Physical evidence of predatory behavior in Tyrannosaurus rex. Proceedings of the National Academy of Sciences of USA, 110, 12560–12564.
Difley, R. (2007). Biostratigraphy of the North Horn Formation at North Horn Mountain, Emery County, Utah. In G.C. Willis (Ed.) Central Utah: Diverse geology of a dynamic landscape (pp. 439–454). Utah Geological Association.
Erickson, G. M., & Currie, P. J. (2006). Tyrannosaur life tables: An example of nonavian dinosaur population biology. Science, 313, 213–217.
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, 772–775.
Forster, C. A. (1996). Species resolution in Triceratops: Cladistic and morphological approaches. Journal of Vertebrate Paleontology, 16, 259–270.
Fowler, D. W. (2017). Revised geochronology, correlation, and dinosaur stratigraphic ranges, correlation, and dinosaur stratigraphic ranges of the Santonian-Maastrichtian formations of the Western Interior of North America. PLoS ONE, 12, e0188426.
Fowler, D. W. (2020). The Hell Creek Formation, Montana: A stratigraphic review and revision based on a sequence stratigraphic approach. Geosciences, 10, 435.
Gates, T. A., Prieto-Márquez, A., & Zanno, L. E. (2012). Mountain building triggered Late Cretaceous North American megaherbivore dinosaur radiation. PLoS ONE, 7, e42135.
Gignac, P., & Erickson, G. M. (2017). The biomechanics behind extreme osteophagy in Tyrannosaurus rex. Scientific Reports, 7, 2012.
Gould, S. J. (2002). The structure of evolutionary theory. Harvard University Press.
Happ, J. (2008). An analysis of predator–prey behavior in a head-to-head encounter between Tyrannosaurus rex and Triceratops. In P. Larson & K. Carpenter (Eds.), Tyrannosaurus rex: The tyrant king (pp. 355–368). Indiana University Press.
Holtz, T. R., Jr. (2008). A critical reappraisal of the obligate scavenging hypothesis for Tyrannosaurus rex and other tyrant dinosaurs. In P. Larson & K. Carpenter (Eds.), Tyrannosaurus rex: The tyrant king (pp. 371–396). Indiana University Press.
Hone, D. (2016). The tyrannosaur chronicles: The biology of the tyrant dinosaurs. Bloomsbury Publishing.
Horner, J. R. (1994). Steak knives, beady eyes, and tiny little arms, a portrait of Tyrannosaurus as a scavenger. Paleontological Society Special Publications, 7, 157–164.
Hunt, G., Hopkins, M. J., & Lidguard, S. (2015). Simple versus complex models of trait evolution. Proceedings of the National Academy of Sciences of USA, 112, 4885–4890.
Hutchinson, J. R., Anderson, F. C., Blemker, S. S., & Delp, S. L. (2005). Analysis of hindlimb muscle moment arms in Tyrannosaurus rex using a three-dimensional musculoskeletal computer model: Implications for stance, gait, and speed. Paleobiology, 31, 676–701.
Hutchinson, J. R., Bates, K. T., Molnar, J., Allen, V., & Makovicky, P. J. (2011). A computational analysis of limb and body dimensions in Tyrannosaurus rex with implications for locomotion, ontogeny, and growth. PLoS ONE, 6, e26037.
Johnson, K. (2008). How old is T. rex? Challenges with the dating of terrestrial strata deposited during the Maastrichtian stage of the Cretaceous period. In P. Larson & K. Carpenter (Eds.), Tyrannosaurus rex: The tyrant king (pp. 63–65). Indiana University Press.
Kaskes, P., Schulp, A. S., Larson, P. L., Smith, J., Kuiper, K. F., & Abels, H. A. (2016). Placing Naturalis' Tyrannosaurus rex specimen in a taphonomic, paleoenvironmental, and integrated stratigraphic framework: Hell Creek Formation, Eastern Montana. In Society of Vertebrate Paleontology 2016 annual meeting abstracts (p. 313).
Larson, P. (1994). Tyrannosaurus sex. Paleontological Society Special Publications, 7, 139–155.
Larson, N. L. (2008a). One hundred years of Tyrannosaurus rex: The skeletons. In P. Larson & K. Carpenter (Eds.), Tyrannosaurus rex: The tyrant king (pp. 1–55). Indiana University Press.
Larson, P. (2008b). Variation and sexual dimorphism in Tyrannosaurus rex. In P. Larson & K. Carpenter (Eds.), Tyrannosaurus rex: The tyrant king (pp. 103–130). Indiana University Press.
Larson, P., & Carpenter, K. (Eds.) (2008). Tyrannosaurus rex, the tyrant king. Indiana University Press.
Larson, P., & Frey, E. (1992). Sexual dimorphism in the abundant Upper Cretaceous theropod Tyrannosaurus rex. Journal of Vertebrate Paleontology, 12, 38A.
LeCain, R. (2010). Magnetostratigraphy of the Hell Creek and lower Fort Union Formations in northeast Montana. Masters Thesis, University of New Hampshire.
Long, K. L., Prothero, D. L., & Syverson, V. J. P. (2020). How do small birds evolve in response to climate change? Data from the long-term record at La Brea tar pits. Integrated Zoology, 15, 249–261.
Mallon, J. C. (2017). Recognizing sexual dimorphism in the fossil record: Lessons from nonavian dinosaurs. Paleobiology, 43, 495–507.
Mallon, J. C. (2019). Competition structured a Late Cretaceous megaherbivorous dinosaur assemblage. Scientific Reports, 9, 15447.
Marshall, C. R., Latorre, D. V., Wilson, C. J., Frank, T. M., Magoulick, K. M., Zimmt, J. B., et al. (2021). Absolute abundance and preservation rate of Tyrannosaurus rex. Science, 372, 284–287.
Molnar, R. E. (1991). The cranial morphology of Tyrannosaurus rex. Palaeontographica A, 217, 137–176.
Molnar, R. E. (2008). Reconstruction of the jaw musculature of Tyrannosaurus rex. In P. Larson & K. Carpenter (Eds.), Tyrannosaurus rex: The tyrant king (pp. 254–281). Indiana University Press.
Myhrvold, N. (2013). Revisiting the estimation of dinosaur growth rates. PLoS ONE, 8, e81917.
Osborn, H. F. (1905). Tyrannosaurus and other Cretaceous carnivorous dinosaurs. Bulletin of the American Museum of Natural History, 21, 259–265.
Paul, G. S. (1988). Predatory dinosaurs of the world. Simon & Schuster.
Paul, G. S. (2008). The extreme lifestyles and habits of the gigantic tyrannosaurid superpredators of the Late Cretaceous of North America and Asia. In P. Larson & K. Carpenter (Eds.), Tyrannosaurus rex: The tyrant king (pp. 307–353). Indiana University Press.
Paul, G. S. (2016). Princeton field guide to dinosaurs. Princeton University Press.
Persons, W. S., & Currie, P. J. (2011). The tail of Tyrannosaurus: Reassessing the size and locomotive importance of the m. caudofemoralis in non-avian theropods. Anatomical Record, 294, 119–131.
Persons, W. S., & Currie, P. J. (2016). An approach to scoring cursorial limb proportions in carnivorous dinosaurs and an attempt to account for allometry. Scientific Reports, 6, 19828.
Persons, W. S., Currie, P. J., & Erickson, G. M. (2019). An older and exceptionally large adult specimen of Tyrannosaurus rex. Anatomical Record, 303, 656–672.
Roloson, M. J., Bamforth, E. L., Scannella, J. B., & Mallon, J. (2021). Triceratops from the uppermost Maastrichtian Frenchman Formation of southern Saskatchewan, and implications for the anagenesis hypothesis. In Society of Vertebrate Paleontology 2021 annual meeting abstracts (p. 221).
Russell, D. A. (1970). Tyrannosaurs from the Late Cretaceous of western Canada. National Museum of Natural Sciences Publications in Paleontology, 1, 1–34.
Ryan, M. J., & Evans, D. C. (2005). Ornithischian dinosaurs. In P. J. Currie & E. B. Koppelhus (Eds.), Dinosaur Provincial Park: A spectacular ancient ecosystem revealed (pp. 312–348). Indiana University Press.
Saitta, E. T., Stockdale, M. T., Longrich, N. E., Bonhomme, V., Benton, M. J., Cuthill, I. C., et al. (2020). An effect size statistical framework for investigating sexual dimorphism in non-avian dinosaurs and other extinct taxa. Biological Journal of the Linnean Society, 131, 231–273.
Salem, B. S., Lamanna, M. C., O'Conner, P., El-Qot, G. M., Shaker, F., Thabet, W. A., et al. (2021). First definitive record of abelisauridae from the Bahariya Formation, Bahariya Oasis, western desert of Egypt increases diversity of large bodied theropods in the middle Cretaceous of northeastern Africa. In Society of Vertebrate Paleontology 2021 annual meeting abstracts (pp. 225–226).
Sampson, S. D., & Loewen, M. A. (2005). Tyrannosaurus rex from the upper Cretaceous North Horn Formation of Utah: Biogeographic and paleoecologic implications. Journal of Vertebrate Paleontology, 25, 469–472.
Scannella, J. B., Fowler, D. W., Goodwin, M. B., & Horner, J. R. (2014). Evolutionary trends in Triceratops from the Hell Creek Formation, Montana. Proceedings of the National Academy of Sciences of USA, 111, 10245–10250.
Schweitzer, M. H., Sou, Z., Avci, R., Asara, J. M., Allen, M. A., Arce, F. T., et al. (2007). Analyses of soft tissue from Tyrannosaurus rex suggest the presence of protein. Science, 316, 277–280.
Schweitzer, M. H., Zheng, W., Zanno, L., Werning, S., & Sugiyama, T. (2016). Chemistry supports the identification of gender-specific reproductive tissue in Tyrannosaurus rex. Scientific Reports, 6, 23099.
Schweitzer, M. H., Wittmeyer, J. L., & Horner, J. R. (2005). Gender-specific reproductive tissue in ratites and Tyrannosaurus rex. Science, 308, 1456–1460.
Sereno, P. C., Tan, L., Brusatte, S., & Kriegstein, H. J. (2009). Tyrannosaurid skeletal design first evolved at small body size. Science, 326, 418–422.
Snively, E., O'Brien, H., Henderson, D. M., Mallison, H., Surring, L. A., Burns, M. E., et al. (2019). Lower rotational inertia and larger leg muscles indicate more rapid turns in tyrannosaurids than in other large theropods. PeerJ, 7, e6432.
Stein, W. W. (2019a). Taking count: a census of dinosaur fossils recovered from the Hell Creek and Lance Formations. Journal of Paleontological Sciences. https://doi.org/10.13140/RG.2.2.13123.55844
Stein, W. W. (2019b). Taking count: A census of dinosaur fossils recovered from the Hell Creek and Lance Formations. Journal of Paleontological Science. https://doi.org/10.13140/RG.2.2.13123.55844
Ullmann, P. V., Macauley, K., Ash, R. D., Shoup, B., & Scannella, J. B. (2021). Taphonomic and diagenetic pathways to protein preservation, Part I: The case of Tyrannosaurus rex specimen MOR 1125. Biology, 10, 1193.
Wick, S. L. (2014). New evidence for the possible occurrence of Tyrannosaurus in West Texas, and discussion of Maastrichtian tyrannosaurid dinosaurs from Big Bend National Park. Cretaceous Research, 50, 52–58.
Wilson, G. P., Dechesne, M., & Anderson, I. R. (2010). New latest Cretaceous mammals from northeastern Colorado with biochronologic and biogeographic implications. Journal of Vertebrate Paleontology, 30, 499–520.
Woodward, H. N., Tremaine, K., Williams, S. A., Zanno, L. E., Horner, J. R., & Myhrvold, N. (2020). Growing up Tyrannosaurus rex: Osteohistology refutes the pygmy “Nanotyrannus” and supports ontogenetic niche partitioning in juvenile Tyrannosaurus. Science. Advances, 6, eaax6250.
Acknowledgements
Our thanks go to Philip Currie, Peter Larson, Ralph Molnar, Kenneth Carpenter, Asier Larramendi, Thomas Carr, James Farlow, Donald Glut, John Horner, Halszka Osmolska, Robert Bakker, Carl Mehling, Mark Loewen, Michael Brett-Surman, Dale Russell, John Scannella, Wes Long, Kevin Seymour, Michael Greenwald, John Harris, Tim Tokaryk, and anonymous reviewers.
Funding
There was no funding for this study.
Author information
Affiliations
Corresponding author
Ethics declarations
Conflict of interest
The authors declare they have no conflict of interest.
Supplementary Information
Below is the link to the electronic supplementary material.
Rights and permissions
About this article
Cite this article
Paul, G.S., Persons, W.S. & Van Raalte, J. The Tyrant Lizard King, Queen and Emperor: Multiple Lines of Morphological and Stratigraphic Evidence Support Subtle Evolution and Probable Speciation Within the North American Genus Tyrannosaurus. Evol Biol (2022). https://doi.org/10.1007/s11692-022-09561-5
Received
Accepted
Published
DOIhttps://doi.org/10.1007/s11692-022-09561-5
Keywords
- Tyrannosaurus
- Theropod
- Dinosaur
- Paleospecies
- Biostratigraphy
- Cretaceous
- Maastrichtian
No comments:
Post a Comment