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Johnson-Ransom E, Li F, Xu X, Ramos R, Midzuk AJ, Thon U, Atkins-Weltman K, Snively E. Comparative cranial biomechanics reveal that Late Cretaceous tyrannosaurids exerted relatively greater bite force than in early-diverging tyrannosauroids. Anat Rec (Hoboken) 2024; 307:1897-1917. [PMID: 37772730 DOI: 10.1002/ar.25326] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Revised: 08/20/2023] [Accepted: 09/05/2023] [Indexed: 09/30/2023]
Abstract
Tyrannosaurus has been an exemplar organism in feeding biomechanical analyses. 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 (Teratophoneus), and large (Tarbosaurus, Daspletosaurus, Gorgosaurus, and Yutyrannus) tyrannosauroids, and incorporation of tyrannosaurines at different ontogenetic stages (small juvenile Tarbosaurus, Raptorex, and mid-sized juvenile Tyrannosaurus). We used jaw muscle force calculations and finite element analysis to comprehend the cranial performance of our tyrannosauroids. Scaled subtemporal fenestrae areas and calculated jaw muscle forces show that broad-skulled tyrannosaurines (Tyrannosaurus, Daspletosaurus, juvenile Tyrannosaurus, and Raptorex) exhibited higher jaw muscle forces than other similarly sized tyrannosauroids (Gorgosaurus, Yutyrannus, and Proceratosaurus). The large proceratosaurid Yutyrannus 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 muscle 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.
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Affiliation(s)
- Evan Johnson-Ransom
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, Illinois, USA
| | - Feng Li
- Tianjin Natural History Museum, Tianjin, China
| | - Xing Xu
- Centre for Vertebrate Evolutionary Biology, Yunnan University, Kunming, China
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
| | - Raul Ramos
- Illustration Department, Rocky Mountain College of Art and Design, Lakewood, Colorado, USA
| | - Adam J Midzuk
- Evolutionary Studies Institute, School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Ulrike Thon
- Informatik Department, Mannheim University of Applied Sciences, Mannheim, Germany
| | - Kyle Atkins-Weltman
- College of Osteopathic Medicine, Oklahoma State University, Tulsa, Oklahoma, USA
| | - Eric Snively
- Oklahoma State University College of Osteopathic Medicine-Cherokee Nation, Tahlequah, Oklahoma, USA
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2
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Therrien F, Zelenitsky DK, Tanaka K, Voris JT, Erickson GM, Currie PJ, DeBuhr CL, Kobayashi Y. Exceptionally preserved stomach contents of a young tyrannosaurid reveal an ontogenetic dietary shift in an iconic extinct predator. SCIENCE ADVANCES 2023; 9:eadi0505. [PMID: 38064561 PMCID: PMC10846869 DOI: 10.1126/sciadv.adi0505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 10/31/2023] [Indexed: 12/18/2023]
Abstract
Tyrannosaurids were large carnivorous dinosaurs that underwent major changes in skull robusticity and body proportions as they grew, suggesting that they occupied different ecological niches during their life span. Although adults commonly fed on dinosaurian megaherbivores, the diet of juvenile tyrannosaurids is largely unknown. Here, we describe a remarkable specimen of a juvenile Gorgosaurus libratus that preserves the articulated hindlimbs of two yearling caenagnathid dinosaurs inside its abdominal cavity. The prey were selectively dismembered and consumed in two separate feeding events. This predator-prey association provides direct evidence of an ontogenetic dietary shift in tyrannosaurids. Juvenile individuals may have hunted small and young dinosaurs until they reached a size when, to satisfy energy requirements, they transitioned to feeding on dinosaurian megaherbivores. Tyrannosaurids occupied both mesopredator and apex predator roles during their life span, a factor that may have been key to their evolutionary success.
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Affiliation(s)
| | - Darla K. Zelenitsky
- Department of Earth, Energy, and Environment, University of Calgary, Calgary, Alberta, Canada
| | - Kohei Tanaka
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Jared T. Voris
- Department of Earth, Energy, and Environment, University of Calgary, Calgary, Alberta, Canada
| | - Gregory M. Erickson
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Philip J. Currie
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Christopher L. DeBuhr
- Department of Earth, Energy, and Environment, University of Calgary, Calgary, Alberta, Canada
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3
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Peterson JE, Tseng ZJ, Brink S. Bite force estimates in juvenile Tyrannosaurus rex based on simulated puncture marks. PeerJ 2021; 9:e11450. [PMID: 34141468 PMCID: PMC8179241 DOI: 10.7717/peerj.11450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 04/22/2021] [Indexed: 11/20/2022] Open
Abstract
Background Bite marks attributed to adult Tyrannosaurus rex have been subject to numerous studies. However, few bite marks attributed to T. rex have been traced to juveniles, leaving considerable gaps in understanding ontogenetic changes in bite mechanics and force, and the paleoecological role of juvenile tyrannosaurs in the late Cretaceous. Methods Here we present bite force estimates for a juvenile Tyrannosaurus rex based on mechanical tests designed to replicate bite marks previously attributed to a T. rex of approximately 13 years old. A maxillary tooth of the juvenile Tyrannosaurus specimen BMR P2002.4.1 was digitized, replicated in dental grade cobalt chromium alloy, and mounted to an electromechanical testing system. The tooth was then pressed into bovine long bones in various locations with differing cortical bone thicknesses at varying speeds for a total of 17 trials. Forces required to replicate punctures were recorded and puncture dimensions were measured. Results Our experimentally derived linear models suggest bite forces up to 5,641.19 N from cortical bone thickness estimated from puncture marks on an Edmontosaurus and a juvenile Tyrannosaurus. These findings are slightly higher than previously estimated bite forces for a juvenile Tyrannosaurus rex of approximately the same size as BMR P2002.4.1 but fall within the expected range when compared to estimates of adult T. rex. Discussion The results of this study offer further insight into the role of juvenile tyrannosaurs in late Cretaceous ecosystems. Furthermore, we discuss the implications for feeding mechanisms, feeding behaviors, and ontogenetic niche partitioning.
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Affiliation(s)
- Joseph E Peterson
- Department of Geology, University of Wisconsin Oshkosh, Oshkosh, Wisconsin, United States of America
| | - Z Jack Tseng
- Department of Integrative Biology and Museum of Paleontology, University of California Berkeley, Berkeley, California, United States of America
| | - Shannon Brink
- Department of Geological Sciences, East Carolina University, Greenville, North Carolina, United States of America
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Marshall CR, Latorre DV, Wilson CJ, Frank TM, Magoulick KM, Zimmt JB, Poust AW. Absolute abundance and preservation rate of Tyrannosaurus rex. Science 2021; 372:284-287. [PMID: 33859033 DOI: 10.1126/science.abc8300] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 03/16/2021] [Indexed: 12/12/2022]
Abstract
Although much can be deduced from fossils alone, estimating abundance and preservation rates of extinct species requires data from living species. Here, we use the relationship between population density and body mass among living species combined with our substantial knowledge of Tyrannosaurus rex to calculate population variables and preservation rates for postjuvenile T. rex We estimate that its abundance at any one time was ~20,000 individuals, that it persisted for ~127,000 generations, and that the total number of T. rex that ever lived was ~2.5 billion individuals, with a fossil recovery rate of 1 per ~80 million individuals or 1 per 16,000 individuals where its fossils are most abundant. The uncertainties in these values span more than two orders of magnitude, largely because of the variance in the density-body mass relationship rather than variance in the paleobiological input variables.
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Affiliation(s)
- Charles R Marshall
- Department of Integrative Biology, University of California, Berkeley, CA, USA. .,University of California Museum of Paleontology, University of California, Berkeley, CA, USA
| | - Daniel V Latorre
- Department of Integrative Biology, University of California, Berkeley, CA, USA.,University of California Museum of Paleontology, University of California, Berkeley, CA, USA
| | - Connor J Wilson
- Department of Integrative Biology, University of California, Berkeley, CA, USA.,University of California Museum of Paleontology, University of California, Berkeley, CA, USA
| | - Tanner M Frank
- Department of Integrative Biology, University of California, Berkeley, CA, USA.,University of California Museum of Paleontology, University of California, Berkeley, CA, USA
| | - Katherine M Magoulick
- Department of Integrative Biology, University of California, Berkeley, CA, USA.,University of California Museum of Paleontology, University of California, Berkeley, CA, USA
| | - Joshua B Zimmt
- Department of Integrative Biology, University of California, Berkeley, CA, USA.,University of California Museum of Paleontology, University of California, Berkeley, CA, USA
| | - Ashley W Poust
- Department of Integrative Biology, University of California, Berkeley, CA, USA.,University of California Museum of Paleontology, University of California, Berkeley, CA, USA.,San Diego Natural History Museum, San Diego, CA, USA
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Rowe AJ, Snively E. Biomechanics of juvenile tyrannosaurid mandibles and their implications for bite force: Evolutionary biology. Anat Rec (Hoboken) 2021; 305:373-392. [PMID: 33586862 DOI: 10.1002/ar.24602] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 02/01/2021] [Accepted: 02/02/2021] [Indexed: 12/25/2022]
Abstract
The tyrannosaurids are among the most well-studied dinosaurs described by science, and analysis of their feeding biomechanics allows for comparison between established tyrannosaurid genera and across ontogeny. 3D finite element analysis (FEA) was used to model and quantify the mechanical properties of the mandibles (lower jaws) of three tyrannosaurine tyrannosaurids of different sizes. To increase evolutionary scope and context for 3D tyrannosaurine results, a broader sample of validated 2D mandible FEA enabled comparisons between ontogenetic stages of Tyrannosaurus rex and other large theropods. It was found that mandibles of small juvenile and large subadult tyrannosaurs experienced lower stress overall because muscle forces were relatively lower, but experienced greater simulated stresses at decreasing sizes when specimen muscle force is normalized. The strain on post-dentary ligaments decreases stress and strain in the posterior region of the dentary and where teeth impacted food. Tension from the lateral insertion of the looping m. ventral pterygoid muscle increases compressive stress on the angular but may decrease anterior bending stress on the mandible. Low mid-mandible bending stresses are congruent with ultra-robust teeth and high anterior bite force in adult T. rex. Mandible strength increases with size through ontogeny in T. rex and phylogenetically among other tyrannosaurids, in addition to that tyrannosaurid mandibles exceed the mandible strength of other theropods at equivalent ramus length. These results may indicate separate predatory strategies used by juvenile and mature tyrannosaurids; juvenile tyrannosaurids lacked the bone-crunching bite of adult specimens and hunted smaller prey, while adult tyrannosaurids fed on larger prey.
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Affiliation(s)
- Andre J Rowe
- School of Earth Sciences, University of Bristol, Bristol, United Kingdom
| | - Eric Snively
- College of Osteopathic Medicine, Oklahoma State University, Tulsa, Oklahoma, USA
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Griffin CT, Stocker MR, Colleary C, Stefanic CM, Lessner EJ, Riegler M, Formoso K, Koeller K, Nesbitt SJ. Assessing ontogenetic maturity in extinct saurian reptiles. Biol Rev Camb Philos Soc 2020; 96:470-525. [PMID: 33289322 DOI: 10.1111/brv.12666] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 10/09/2020] [Accepted: 10/28/2020] [Indexed: 01/06/2023]
Abstract
Morphology forms the most fundamental level of data in vertebrate palaeontology because it is through interpretations of morphology that taxa are identified, creating the basis for broad evolutionary and palaeobiological hypotheses. Assessing maturity is one of the most basic aspects of morphological interpretation and provides the means to study the evolution of ontogenetic changes, population structure and palaeoecology, life-history strategies, and heterochrony along evolutionary lineages that would otherwise be lost to time. Saurian reptiles (the least-inclusive clade containing Lepidosauria and Archosauria) have remained an incredibly diverse, numerous, and disparate clade through their ~260-million-year history. Because of the great disparity in this group, assessing maturity of saurian reptiles is difficult, fraught with methodological and terminological ambiguity. We compiled a novel database of literature, assembling >900 individual instances of saurian maturity assessment, to examine critically how saurian maturity has been diagnosed. We review the often inexact and inconsistent terminology used in saurian maturity assessment (e.g. 'juvenile', 'mature') and provide routes for better clarity and cross-study coherence. We describe the various methods that have been used to assess maturity in every major saurian group, integrating data from both extant and extinct taxa to give a full account of the current state of the field and providing method-specific pitfalls, best practices, and fruitful directions for future research. We recommend that a new standard subsection, 'Ontogenetic Assessment', be added to the Systematic Palaeontology portions of descriptive studies to provide explicit ontogenetic diagnoses with clear criteria. Because the utility of different ontogenetic criteria is highly subclade dependent among saurians, even for widely used methods (e.g. neurocentral suture fusion), we recommend that phylogenetic context, preferably in the form of a phylogenetic bracket, be used to justify the use of a maturity assessment method. Different methods should be used in conjunction as independent lines of evidence when assessing maturity, instead of an ontogenetic diagnosis resting entirely on a single criterion, which is common in the literature. Critically, there is a need for data from extant taxa with well-represented growth series to be integrated with the fossil record to ground maturity assessments of extinct taxa in well-constrained, empirically tested methods.
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Affiliation(s)
- Christopher T Griffin
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
| | - Michelle R Stocker
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
| | - Caitlin Colleary
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Vertebrate Paleontology, Cleveland Museum of Natural History, 1 Wade Oval Drive, Cleveland, OH, 44106, U.S.A
| | - Candice M Stefanic
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Anatomical Sciences, Stony Brook University, 100 Nicolls Road, Stony Brook, NY, 11794, U.S.A
| | - Emily J Lessner
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Pathology and Anatomical Sciences, University of Missouri, 1 Hospital Drive, Columbia, MO, 65212, U.S.A
| | - Mitchell Riegler
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Geological Sciences, University of Florida, 241 Williamson Hall, Gainesville, FL, 32611, U.S.A
| | - Kiersten Formoso
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Earth Sciences, University of Southern California, 3651 Trousdale Pkwy, Los Angeles, CA, 90089, U.S.A
- Dinosaur Institute, Natural History Museum of Los Angeles County, 900 W Exposition Boulevard, Los Angeles, CA, 90007, U.S.A
| | - Krista Koeller
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Biology, University of Florida, 220 Bartram Hall, Gainesville, FL, 32611, U.S.A
| | - Sterling J Nesbitt
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
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Woodward HN, Tremaine K, Williams SA, Zanno LE, Horner JR, Myhrvold N. Growing up Tyrannosaurus rex: Osteohistology refutes the pygmy " Nanotyrannus" and supports ontogenetic niche partitioning in juvenile Tyrannosaurus. SCIENCE ADVANCES 2020; 6:eaax6250. [PMID: 31911944 PMCID: PMC6938697 DOI: 10.1126/sciadv.aax6250] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 11/01/2019] [Indexed: 06/10/2023]
Abstract
Despite its iconic status as the king of dinosaurs, Tyrannosaurus rex biology is incompletely understood. Here, we examine femur and tibia bone microstructure from two half-grown T. rex specimens, permitting the assessments of age, growth rate, and maturity necessary for investigating the early life history of this giant theropod. Osteohistology reveals these were immature individuals 13 to 15 years of age, exhibiting growth rates similar to extant birds and mammals, and that annual growth was dependent on resource abundance. Together, our results support the synonomization of "Nanotyrannus" into Tyrannosaurus and fail to support the hypothesized presence of a sympatric tyrannosaurid species of markedly smaller adult body size. Our independent data contribute to mounting evidence for a rapid shift in body size associated with ontogenetic niche partitioning late in T. rex ontogeny and suggest that this species singularly exploited mid- to large-sized theropod niches at the end of the Cretaceous.
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Affiliation(s)
- Holly N. Woodward
- Department of Anatomy and Cell Biology, Oklahoma State University Center for Health Sciences, 1111 W. 17th St., Tulsa, OK 74104, USA
| | - Katie Tremaine
- Department of Earth Science, Montana State University, P.O. Box 173480, Bozeman, MT 59717, USA
- Museum of the Rockies, Montana State University, 600 W. Kagy Blvd., Bozeman, MT 59717, USA
| | - Scott A. Williams
- Museum of the Rockies, Montana State University, 600 W. Kagy Blvd., Bozeman, MT 59717, USA
| | - Lindsay E. Zanno
- Paleontology, North Carolina Museum of Natural Sciences, 11 W. Jones St., Raleigh, NC 27601, USA
- Department of Biological Sciences, North Carolina State University, 3510 Thomas Hall, Campus Box 7614, Raleigh, NC 2769, USA
| | - John R. Horner
- Chapman University, 1 University Dr., Orange, CA 92866, USA
| | - Nathan Myhrvold
- Intellectual Ventures, 3150 139th Avenue Southeast, Bellevue, WA 98005, USA
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