Tyrannosaurus rex Osborn 1905
Creators: name: Peterson, Joseph E.
name: Karsen N. Daus
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Reptilia
Dinosauria
Tyrannosauridae
Tyrannosaurus
Tyrannosaurus rex

description: Here we report on the presence of feeding traces on the caudal vertebra of a hadrosaurid dinosaur (BMR P2007.4.1, ‘‘Constantine’’). Based on the shape and orientation of the traces, and the known fauna of the Hell Creek Formation, they are interpreted to be feeding traces of a large theropod dinosaur, such as <i>Tyrannosaurus rex</i> (<i>Erickson &amp; Olson, 1996</i>; <i>Horner, Goodwin &amp; Myhrvold, 2011</i>). By comparing the dimensions and spacing of the traces with the maxillae and dentaries of specimens of <i>Tyrannosaurus rex</i> of different ontogenetic stages, we interpret these tooth marks to be feeding traces from a juvenile <i>Tyrannosaurus rex</i> and discuss the insights the specimen provides for juvenile tyrannosaur feeding behavior. Geologic setting Specimen BMR P2007.4.1 is a partial hadrosaurid skeleton collected from the Upper Cretaceous Hell Creek Formation of Carter County, southeastern Montana in the Powder River Basin (Fig. 1). This specimen was collected on public lands under BLM Permit # M96842-2007 issued to Northern Illinois University and is accessioned at the Burpee Museum of Natural History in Rockford, IL. Exact coordinates for the location are on file in the paleontology collections at the Burpee Museum of Natural History (BMR), where the specimen is reposited. The collection locality is composed of a 4 m fine-grained, gray-tan lenticular sandstone within a larger surrounding blocky mudstone unit (Fig. 2). The sandstone lacks bedforms, resulting from either (a) rapid accumulation (resulting in a lack of sedimentary structures), or (b) sedimentary structures that were obliterated by later currents or bioturbation, and is rich in rounded and weathered microvertebrate remains. The site is stratigraphically positioned approximately 44 m above the underlying Fox Hills–Hell Creek contact and overlies 0.5 m of siderite, which sits above a 5 m blocky mudstone. Grains are subrounded to subangular. Microvertebrate and fragmented macrovertebrate fossils are abundant and heavily rounded and abraded (<i>Peterson, Scherer &amp; Huffman, 2011</i>). The fine-grained composition suggests a channel-fill deposit, overlying a floodplain deposit (<i>Murphy, Hoganson &amp; Johnson, 2002</i>; <i>Peterson, Scherer &amp; Huffman, 2011</i>). The taphonomic distribution of the elements and their stratigraphic position suggests the skeleton was subaerially exposed on a floodplain for a considerable period of time prior to burial, allowing for weathering, disarticulation, and removal of many skeletal elements. MATERIALS &amp; METHODS Specimen BMR P2007.4.1 consists of weathered pelvic elements (sacrum, left and right ilia), three dorsal vertebrae, and two proximal caudal vertebrae (Fig. 3, Table 1). The dorsal vertebrae were too weathered for collection, though their dimensions and relative locations within the quarry assemblage were measured and documented. Additionally, a series of heavily-weathered bone fragments and a small shed theropod tooth (<i>Saurornithoides sp.</i>) were also collected. The ilium of BMR P2007.4.1 possesses a number of hadrosaurid characters such as (1) a shallow morphology, (2) a ∼ 23 ◦ preacetabular process in medial view relative to the main body, and (3) a well-developed supra-acetabular process caudal to the acetabulum. While these characters are common among hadrosaurids, the stratigraphic position of BMR P2007.4.1 suggests it is attributable to the Late Cretaceous hadrosaurid <i>Edmontosaurus</i> (i.e., <i>Brett-Surman &amp; Wagner, 2007</i>; <i>Campione, 2014</i>). The centra of the two caudal vertebrae lack any evidence for hemal arch attachments, suggesting they are among the more cranial-positioned caudal vertebrae, such as C1–C4 (<i>Campione, 2014</i>). One of the caudal vertebrae possesses three v-shaped indentations on the ventral surface of the centrum (Figs. 4A–4E; Figs. S1 and S2). These traces feature collapsed cortical bone within the indentation, producing puncture marks (<i>sensu Binford, 1981</i>). The punctures penetrate 5 mm deep, are spaced 68 mm apart from their apical centers, show no signs of healing, and are inferred to have been created postmortem as feeding traces (e.g., <i>Noto, Main &amp; Drumheller, 2012</i>; <i>Hone &amp; Tanke, 2015</i>; <i>McLain et al., 2018</i>). The v-shape preserved in each puncture indicates that the original teeth would have possessed a prominent keel, though no striations from serration marks are present in the traces (<i>sensu D’Amore &amp; Blumensehine, 2009</i>). The large size and shape of the punctures suggests that they were produced by a largeto medium-bodied carnivore. Such carnivores from the Hell Creek Formation include tyrannosaurs such as <i>Tyrannosaurus rex</i> (<i>Erickson &amp; Olson, 1996</i>; <i>Horner, Goodwin &amp;</i> <i>Myhrvold, 2011</i>), medium-sized dromaeosaurids such as <i>Dakotaraptor steini</i> (<i>DePalma et al., 2015</i>), and crocodylians such as <i>Borealosuchus sternbergii</i>, <i>Brachychampsa montana</i>, and <i>Thoracosaurus neocesariensis</i> (<i>Matsumoto &amp; Evans, 2010</i>). By comparing the shape and orientation of the traces to the teeth of these carnivores from the Hell Creek Formation, they are hypothesized to be bite marks from a large theropod dinosaur, such as <i>Tyrannosaurus rex</i> (<i>Erickson &amp; Olson, 1996</i>); crocodylian teeth are circular in cross-section and too small, and dromaeosaurid teeth—even large dromaeosaurids such as <i>D. steini</i> —are too small and laterally-compressed to have produced the punctures observed on BMRP2007.4.1. To test this hypothesis, the punctures on the caudal vertebra of BMR P2007.4.1 were first coated in ReboundTM 25 platinum-cure silicone rubber (Smooth-On) in order to make a silicone peel of the punctures in order to better visualize the morphology and dimensions of the teeth responsible for the traces (Figs. 5A–5B; Figs. S3 and S4). These ‘‘teeth’’ were then compared with the dental dimensions and spacing of two <i>Tyrannosaurus</i> maxillae and dentaries. To approximate the ontogenetic stage of the tyrannosaur, a late-stage juvenile specimen (BMR P2002.4.1, ‘‘Jane’’) histologically determined to be approximately 11–12 years old at the time of death (<i>Erickson et al., 2006</i>) that possesses laterally compressed, sharp crowns, and a mature specimen (BHI 3033, ‘‘Stan’’) with robust, blunt crowns were utilized. All specimens were digitized via triangulated laser texture scanning with a NextEngine 3D Laser Scanner, capturing data at seven scanning divisions in high-definition (2.0k points/in 2). The resulting digital models were built with the NextEngine ScanStudio HD Pro version 2.02, and finalized as STL models (Figs. S1–S8). Scanning was conducted at the Department of Geology at the University of Wisconsin-Oshkosh in Oshkosh, WI. The tooth spacing of both adult and late-stage juvenile tyrannosaur maxillae and dentaries were measured for both immediately-adjacent teeth and teeth from alternating replacement positions (i.e., <i>Zahnreihen</i>), and compared with the spacing of the punctures (Figs. 6A–6B), similar to <i>Fahlke</i> ’s (<i>2012</i>) investigation of likely <i>Basilosaurus</i> bite marks on specimens the smaller whale <i>Dorudon</i>. Furthermore, the cross-sectional morphology of adult and late-stage juvenile tyrannosaur maxillae and dentaries were measured labiolingually and mesiodistally at a 5 mm apical depth for each tooth crown, and plotted with measurements from the punctures found on BMR P2007.4.1 (Fig. 7). RESULTS The mesiodistal width measurements from the silicone peel taken from BMR P2007.4.1 average 7.8 mm and the labiolingual depth average was 5.2 mm. Maxillary and dentary teeth of the adult <i>Tyrannosaurus</i> (BHI 3033) were found to be too large and widely spaced to have produced the punctures (Figs. 7, 8A and 8B; Figs. S4 and S5; Tables 2A–2C). For BHI 3033, the average dentary tooth crown mesiodistal width at 5 mm depth was 7.13 mm, and the average dentary tooth crown labiolingual depth at 5 mm was 4.10 mm. The average maxillary crown mesiodistal width at 5 mm were 7.72 mm, and the average maxillary crown labiolingual depth at 5 mm averaged to 4.21 mm. However, the teeth of BMR P2002.4.1 produced similarly shaped punctures at 5 mm apical depth (Figs. 7 and 9; Figs. S7 and S8; Tables 2B–2C). The puncture measurements taken from the peel, BMR P2007.4.1 demonstrate a mesiodistal width and labiolingual depth consistent with the measurements taken from the maxillary and dentary teeth of the late-stage juvenile <i>Tyrannosaurus</i>. When plotted against the mesiodistal width and labiolingual depth of the maxillary teeth, measurements from the peel taken from BMR P2007.4.1 fall well within the cluster radius created by the late-stage juvenile <i>Tyrannosaurus</i>, BMR P2002.4.1 (Fig. 7). Furthermore, the inferred crown spacing of the punctures closely matched those of the late-stage juvenile tyrannosaur maxilla (Tables 3A–3B). DISCUSSION AND CONCLUSIONS While feeding traces and bite marks attributed to mature tyrannosaurids are welldocumented in common Late Cretaceous taxa such as hadrosaurids and ceratopsians (i.e., <i>Fiorillo, 1991</i>; <i>Erickson et al., 1996</i>; <i>Erickson &amp; Olson, 1996</i>; <i>Jacobsen, 1998</i>; <i>Farlow &amp; Holtz, 2002</i>; <i>Fowler &amp; Sullivan, 2006</i>; <i>Peterson et al., 2009</i>; <i>Bell &amp; Currie, 2009</i>; <i>Fowler et al., 2012</i>; <i>DePalma et al., 2013</i>; <i>McLain et al., 2018</i>), the identification of juvenile tyrannosaur feeding traces adds insight into the role of juvenile theropods in Cretaceous ecosystems. The dimensions and spacing of the punctures closely matches the maxillary teeth of BMR P2002.4.1, a late-stage juvenile (11–12 yr old) tyrannosaur which incidentally itself possesses morphologically similar craniofacial lesions previously interpreted as a conspecific bite (<i>Peterson et al., 2009</i>). <i>Longrich et al. (2010)</i> reported on evidence of cannibalism in <i>T. rex</i> based on a number of bitten and scored remains of <i>Tyrannosaurus rex</i>, some attributed to juvenile or subadult individuals. However, many of these traces resemble the ‘puncture and pull’ bite marks that have previously been attributed to <i>T. rex</i> (<i>Erickson et al., 1996</i>; <i>Erickson &amp; Olson, 1996</i>), and also include furrows and scores (<i>sensu Binford, 1981</i>). Correlating traces in bone, such as tooth marks, to specific taxa and ontogenetic stages usually requires direct comparisons (e.g., <i>Peterson et al., 2009</i>; <i>Fahlke, 2012</i>). However, in cases where direct comparisons are not available, estimates can be made for tooth size, morphology, and spacing based on ontogenetic trajectories. While bite marks and feeding traces attributable to younger juvenile and hatchling tyrannosaurs have not yet been identified, the punctures present on the caudal vertebra of BMR P2007.4.1 provide direct evidence that late-stage juvenile <i>Tyrannosaurus rex</i> such as BMR P2002.4.1 possessed—at least in part—a similar diet as adults. While bite marks resulting from active predation cannot easily be distinguished from postmortem feeding traces, the ventral position of the punctures in the caudal centrum of BMR P2007.4.1 suggests that the feeding was taking place postmortem with the hadrosaur already on its side (<i>Chure, Fiorillo &amp; Jacobsen, 1998</i>). The afflicted vertebra is from the cranial-most part of the tail. Observations of the feeding behaviors of carnivoran mammals and birds indicate that in most cases, consumption of the axial skeleton occurs after limbs and viscera have been consumed (e.g., <i>Hill, 1980</i>; <i>Haglund, 1997</i>; <i>Carson, Stefan &amp; Powell, 2000</i>; <i>Behrensmeyer, Stayton &amp; Chapman, 2003</i>). Hadrosaur tails had substantial muscles such as m. ilio-ischocaudalis and m. caudofemoralis longus (<i>Persons &amp; Currie, 2014</i>) that might be a target of early stage consumption. However, the ventral bite traces on BMR P2007.4.1 suggest that the tyrannosaur was feeding after the haemal complexes and most of the superficial hypaxial muscles and m. caudofemoralis longus had been removed. As such the punctures on BMR P2007.4.1 suggest later-stage carcass consumption and postmortem feeding behaviors. The identification of penetrating bite marks attributable to not only <i>Tyrannosaurus rex</i>, but an individual of 11–12 years of age can potentially allow for the determination of the ontogeny of bite force in <i>Tyrannosaurus rex</i> and for comparison with other theropods (e.g., <i>Barrett &amp; Rayfield, 2006</i>; <i>Gignac et al., 2010</i>; <i>Bates &amp; Falkingham, 2012</i>). Studies on the estimated bite forces of an adult <i>Tyrannosaurus rex</i> have yielded a wide range of results. Estimates based on muscle volume proposed bite forces between 8,526 and 34,522 N, coupled with tooth pressures of 718–2,974 MPa, and a unique tooth morphology and arrangement to promote fine fragmentation of bone during osteophagy (<i>Gignac &amp; Erickson, 2017</i>). However, estimates incorporating likely muscle fiber length produced results over 64,000 N for adult <i>T. rex</i> (<i>Bates &amp; Falkingham, 2018</i>). Juvenile <i>T. rex</i> such as BMR P2002.4.1 have much narrower and blade-like tooth morphologies and were unlikely to have been able to withstand similar bite forces at this ontogenetic stage. <i>Bates &amp; Falkingham (2012)</i> estimated a maximum bite force for BMR P2002.4.1 at 2,400–3,850 N, and hypothesized that an increase in bite force during growth could indicate a change in feeding behavior and dietary partitioning while approaching adulthood. Observations on extant crocodylians have documented a wide variety of dietary partitioning during ontogeny (e.g., <i>Tucker et al., 1996</i>; <i>Platt et al., 2006</i>; <i>Platt et al., 2013</i>). In the American crocodile (<i>Crocodylus acutus</i>), hatchling and small juveniles have a dietary overlap of over 80%, commonly feeding upon insects and crustaceans (<i>Platt et al., 2013</i>). Alternatively, larger juveniles, subadults, and adults possess a dietary overlap of over 75%, consisting of more birds, mammals, fish, and other reptiles (<i>Platt et al., 2013</i>). Comparable ontogenetic dietary partitions were also observed in Morelet’s crocodile (<i>Crocodylus moreletii</i>) (<i>Platt et al., 2006</i>), and in Australian freshwater crocodiles (<i>Crocodylus johnstoni</i>) (<i>Tucker et al., 1996</i>). However, crocodylians are less discriminant of food sources when scavenging (e.g., <i>Antunes, 2017</i>). While the punctures present on BMR P2007.4.1 are likely from postmortem scavenging behaviors of a juvenile tyrannosaur, the degree of dietary overlap or partitioning between juvenile and adult tyrannosaurs remains unresolved. Despite not yet possessing the same feeding mechanisms of an adult <i>Tyrannosaurus rex</i> (i.e., bone-crushing and osteophagy), the punctures present on BMR P2007.4.1 demonstrate that late-stage juvenile and subadult tyrannosaurs were already biomechanically capable of puncturing bone during feeding, and were doing so without the large, blunt dental crowns of adults. Further identification of tyrannosaur feeding traces from different ontogenetic stages coupled with experimental studies of the biomechanics of tyrannosaur bite forces may reveal more insight into dynamic dietary trends and ecological role of <i>Tyrannosaurus rex</i> throughout ontogeny.
description: Published as part of <i>Joseph E. Peterson &amp; Karsen N. Daus, 2019, Feeding traces attributable to juvenile Tyrannosaurus rex offer insight into ontogenetic dietary trends, pp. 1-17 in PeerJ (e 6573) (e 6573) 7 (3)</i> on pages 2-13, DOI: 10.7717/peerj.6573, http://zenodo.org/record/3749254
description: {"references": ["Erickson GM, Olson KH. 1996. Bite marks attributable to Tyrannosaurus rex: a preliminary description and implications. Journal of Vertebrate Paleontology 16 (1): 175 - 178 DOI 10.1080 / 02724634.1996.10011297.", "Horner JR, Goodwin MB, Myhrvold N. 2011. Dinosaur census reveals abundant Tyrannosaurus and rare ontogenetic stages in the Upper Cretaceous Hell Creek Formation (Maastrichtian), Montana, USA. PLOS ONE 6 (2): e 16574 DOI 10.1371 / journal. pone. 0016574.", "Peterson JE, Scherer RP, Huffman KM. 2011. Methods of microvertebrate sam- pling and their influences on taphonomic interpretations. Palaios 26 (2): 81 - 88 DOI 10.2110 / palo. 2010. p 10 - 080 r.", "Murphy EC, Hoganson JW, Johnson KR. 2002. Lithostratigraphy of the Hell Creek Formation in North Dakota. In: Hartman JH, Johnson KR, Nichols DJ, eds. The hell creek formation and the cretaceous-tertiary boundary in the Northern great plains: an integrated continental record of the end of the cretaceous. Geological Society of America Special Papers 361, Boulder, Colorado: Geological Society of America, 9 - 34.", "Brett-Surman MK, Wagner JR. 2007. Discussion of character analysis of the appendicular anatomy of Campanian and Maastrichtian North American hadrosauridsvariation and ontogeny. In: Carpenter K, ed. Horns and beaks-ceratopsian and ornithopod dinosaurs. Bloomington: Indiana University Press, 135 - 169.", "Campione NE. 2014. Postcranial anatomy of Edmontosaurus regalis (Hadrosauridae) from the Horseshoe Canyon Formation, Alberta, Canada. In: Ebert DA, Evans DE, eds. Hadrosaurs. Bloomington and Indianapolis: Indiana University Press, 208 - 244.", "Binford LR. 1981. Bones: ancient men and modern myths. New York: Academic Press, 320.", "Noto CR, Main DJ, Drumheller SK. 2012. Feeding traces and paleobiology of a Cretaceous (Cenomanian) crocodyliform: example from the Woodbine Formation of Texas. Palaios 27 (2): 105 - 115 DOI 10.2110 / palo. 2011. p 11 - 052 r.", "Hone DWE, Tanke DH. 2015. Pre- and postmortem tyrannosaurid bite marks on the remains of Daspletosaurus (Tyrannosaurinae: Therpoda) from Dinosaur Provincial Park, Alberta, Canada. PeerJ 3: e 885 DOI 10.7717 / peerj. 885.", "McLain MA, Nelsen D, Snyder K, Griffin CT, Siviero B, Brand LR, Chadwick AV. 2018. Tyrannosaur cannibalism: a case of a tooth-traced tyrannosaurid bone in the Lance Formation (Maastrichtian), Wyoming. Palaios 33 (4): 164 - 173 DOI 10.2110 / palo. 2017.076.", "D'Amore DC, Blumensehine RJ. 2009. Komodo monitor (Varanus komodoensis) feeding behavior and dental function reflected through tooth marks on bone surfaces, and the application to ziphodont paleobiology. Paleobiology 35 (4): 525 - 552 DOI 10.1666 / 0094 - 8373 - 35.4.525.", "DePalma RA, Burnham DA, Martin LD, Larson PT, Bakker RT. 2015. The first giant raptor (Theropoda: Dromaeosauridae) from the Hell Creek Formation. Paleontological Contributions 14: 1 - 16 DOI 10.17161 / paleo. 1808.18764.", "Matsumoto R, Evans SE. 2010. Choristoderes and the freshwater assemblages of Laurasia. Journal of Iberian Geology 36 (2): 253 - 274 DOI 10.5209 / rev _ JIGE. 2010. v 36. n 2.11.", "Erickson GM, Currie PJ, Inouye BD, Winn AA. 2006. Tyrannosaur life tables: An example of nonavian dinosaur population biology. Science 313: 213 - 217 DOI 10.1126 / science. 1125721.", "Fiorillo AR. 1991. Prey bone utilization by predatory dinosaurs. Palaeogeography, Palaeoclimatology, Palaeoecology 88 (3 - 4): 157 - 166 DOI 10.1016 / 0031 - 0182 (91) 90062 - V.", "Jacobsen AR. 1998. Feeding behavior in carnivorous dinosaurs determined by tooth marks on dinosaur bones. Historical Biology 13: 17 - 26 DOI 10.1080 / 08912969809386569.", "Farlow JO, Holtz TR. 2002. The fossil record of predation in dinosaurs. In: Kowalewski M, Kelley PH, eds. Paleontological Society Paper 8. New York: Cambridge University Press, 251 - 265.", "Fowler DW, Sullivan RM. 2006. A ceratopsid pelvis with toothmarks from the Upper Cretaceous Kirtland Formation, New Mexico: evidence of late Campanian tyrannosaurid feeding behavior. New Mexico Museum of Natural History and Science Bulletin 35: 127 - 130.", "Peterson JE, Henderson MD, Scherer RP, Vittore CP. 2009. Face biting on a juvenile tyrannosaurid and behavioral implications. Palaios 24: 780 - 784 DOI 10.2110 / palo. 2009. p 09 - 056 r.", "Bell PR, Currie PJ. 2009. A tyrannosaur jaw bitten by a confamilial: scavenging or fatal agonism? Lethaia 43 (2): 278 - 281 DOI 10.1111 / j. 1502 - 3931.2009.00195. x.", "Fowler DW, Scannella JB, Goodwin MB, Horner JR. 2012. How to eat a Triceratops: large sample sample of toothmarks provides new insight into the feeding behavior of Tyrannosaurus [Abstract S 96 A]. Journal of Vertebrate Paleontology 32.", "DePalma RA, Burnham DA, Martin LD, Rothschild BM, Larson PL. 2013. Physical evidence of predatory behavior in Tyrannosaurus rex. Proceedings of the Na- tional Academy of Sciences of the United States of America 110 (31): 12560 - 12564 DOI 10.1073 / pnas. 1216534110.", "Longrich NR, Horner JR, Erickson GM, Currie PJ. 2010. Cannibalism in Tyrannosaurus rex. PLOS ONE 5 (10): e 13419 DOI 10.1371 / journal / pone. 0013419.", "Fahlke JM. 2012. Bite marks revisited-evidence for middle-to-late Eocene Basilosaurus isis predation on Dorudon atrox (both Cetacea, Basilosauridae). Palaeontologica Electronica 15 (3): 32 A, 16 p. palaeo-electronica. org / content / 2012 - issue- 3 - articles / 339 - archaeocete-predation.", "Chure DJ, Fiorillo AR, Jacobsen A. 1998. Prey bone utilization by predatory dinosaur sin the Late Jurassic of North America, with comments on prey bone use by dinosaurs throughout the Mesozoic. Gaia 15: 227 - 232.", "Hill AP. 1980. Early postmortem damage to the remains of some contemporary East African mammals. In: Behrensmeyer AK, Hill AP, eds. Fossils in the making. Vertebrate taphonomy and paleoecology. Chicago: University of Chicago Press, 131 - 152.", "Haglund WD. 1997. Dogs and coyotes: postermorem involvement with human remains. In: Haglund WD, Sorg MH, eds. Forensic taphonomy. Boca Raton: CRC Press, 367 - 382.", "Carson EA, Stefan VH, Powell JF. 2000. Skeletal manifestations of bear scavenging. Journal of Forensic Sciences 45 (3): 515 - 526.", "Behrensmeyer AK, Stayton CT, Chapman RE. 2003. Taphonomy and ecology of modern avifaunal remains from Amboseli Park, Kenya. Paleobiology 29 (1): 52 - 70 DOI 10.1666 / 0094 - 8373 (2003) 029 &lt;0052: TAEOMA&gt; 2.0. CO; 2.", "Persons WS, Currie PJ. 2014. Duckbills on the run: the cursorial abilities of hadrosaurs and implications for hadrosaur-avoidance strategies. In: Eberth DA, Evans DE, eds. Hadrosaurs. Bloomington and Indianapolis: Indiana University Press, 449 - 458.", "Barrett PM, Rayfield EJ. 2006. Ecological and evolutionary implications of di- nosaur feeding behavior. Trends in Ecology and Evolution 21 (4): 217 - 224 DOI 10.1016 / j. tree. 2006.01.002.", "Gignac PM, Makovicky PJ, Erickson GM, Walsh RP. 2010. A description of Deinonychus antirrhopus bite marks and estimates of bite force using tooth indentation simulations. Journal of Vertebrate Paleontology 30 (4): 1169 - 1177 DOI 10.1080 / 02724634.2010.483535.", "Bates KT, Falkingham PL. 2012. Estimating maximum bite force in Tyrannosaurus rex using multi-body dynamics. Biology Letters 8: 660 - 664 DOI 10.1098 / rsbl. 2012.0056.", "Gignac PM, Erickson GM. 2017. The biomechanics behind extreme osteophagy in Tyrannosaurus rex. Scientific Reports 7 (2012): 1 - 10 DOI 10.1038 / s 41598 - 017 - 02161 - w.", "Bates KT, Falkingham PL. 2018. The importance of muscle architecture in biomechanical reconstructures of extinct animals: a case study using Tyrannosaurus rex. Journal of Anatomy 233: 635 - 635 DOI 10.1111 / joa. 12874.", "Tucker AD, Limpus CJ, McCallum HI, McDonald KR. 1996. Ontogenetic dietary partitioning by Crocodylus johnstoni during the dry season. Copeia 1996 (4): 978 - 988 DOI 10.2307 / 1447661.", "Platt SG, Rainwater TR, Finger AG, Thorbjarnarson JB, Anderson TA, McMurry ST. 2006. Food habits, ontogenetic dietary partitioning and observations of foraging behaviour of Morelet's crocodile (Crocodylus moreletii) in northern Belize. Herpetological Journal 16: 281 - 290.", "Platt SG, Thorbjarnarson JB, Rainwater TR, Martin DR. 2013. Diet of the American crocodile (Crocodylus acutus) in marine environments of coastal Belize. Journal of Herpetology 47 (1): 1 - 10 DOI 10.1670 / 12 - 077.", "Antunes MT. 2017. Huge miocene crocodilians from western Europe: predation, comparisons with the '' False Gharial' ' and size. Anuario do Instituto de Geociencias 40 (3): 117 - 130 DOI 10.11137 / 2017.3.117.130."]}