This timeline of tyrannosaur research is a chronological listing of events in the
Delaware stories about smoking the bones of ancient monsters to have wishes granted.[3]
Tyrannosaur remains were among the first dinosaur
Dinosaur Renaissance by decades.[6] Later in the century, Cope's hated rival Othniel Charles Marsh would discover that the name Laelaps had already been given to a parasitic mite, and would rename the dinosaur Dryptosaurus.[7]
Early in the
coelurosaurs). Tyrannosaurid anatomy led some early researchers like Matthew, Brown, and Huene, to cast doubt on the validity of this division. However, the traditional carnosaur-coelurosaur division persisted until the early 1990s, when the application of cladistics to tyrannosaur systematics confirmed the doubts of early workers and found tyrannosaurs to be large-bodied coelurosaurs.[10]
Another debate about tyrannosaurs would not be settled until the early 21st century: their diet. Early researchers were so overwhelmed by the massive bulk of
Jack Horner but was shown false by Kenneth Carpenter, who reported the discovery of a partially healed tyrannosaur bite wound on an Edmontosaurus annectens tail vertebra, proving that T. rex at least sometimes pursued living victims.[11]
Laelaps aquilunguis.[13] This discovery proved that theropod dinosaurs walked on their hind limbs rather than on all fours like in earlier reconstructions.[14] He also erected the family Deinodontidae.[9]
Gorgosaurus sternbergi.[13] They still regarded tyrannosaurs as members of the family Deinodontidae.[9]
Friedrich von Huene regarded tyrannosaurs as members of the family Deinodontidae[9] and advocated for the hypothesis that tyrannosaurs were more closely related to the small carnivores called coelurosaurs than to other large carnivorous dinosaurs like Allosaurus and Megalosaurus.[10]
Robert T. Bakker interpreted the "ornamentation" seen on the snouts and around the eyes of many tyrannosaurs were displays for other members of the same tyrannosaur species.[18]
Farlow and others studied tyrannosaur tooth biomechanics, finding them to be more resistant to forces in both the front-to-back and side-to-side planes than the more blade-like teeth of other carnivorous dinosaurs.[19]
Scotty the T. rex is discovered near Eastend, Saskatchewan.
Pérez-Moreno and others performed another phylogenetic analysis of the Tyrannosauridae and found additional support for reclassifying the family as coelurosaurs.[10] They found tyrannosaurids to lie outside of the Maniraptoriformes. In other words, they are less closely related to birds than the ostrich dinosaurs are.[10]
Thomas Holtz performed another phylogenetic analysis of the Tyrannosauridae and found additional support for reclassifying the family as coelurosaurs.[10] He found that within the coelurosaurs, tyrannosaurs were arctometatarsalians. In other words, they were more closely related to the ostrich dinosaurs than to birds.[10]
Horner interpreted tyrannosaurids as scavengers.[11]
Martin Lockley and Hunt described a possible Tyrannosaurus footprint.[19]
Emily B. Giffin observed that the brachial plexus of the tyrannosaurid neural canal was smaller than those of other theropods, suggesting that tyrannosaurids really did have reduced forlimb function.[19]
Farlow and others calculated that an adult T. rex running at 20 m/s or faster would sustain fatal injuries if it tripped, suggesting that they didn't actually run that fast.[21]
Holtz observed that tyrannosaurids had the longest limbs relative to their body size of any theropod dinosaurs apart from the ostrich dinosaurs and a small, slender
ceratosaur called Elaphrosaurus. Although the ostrich dinosaur on average had relatively longer limbs overall, the ratios of femur length to the length of the tibia and fibula were actually very close between the smaller tyrannosaurs and the largest ostrich dinosaurs. Holtz found ostrich dinosaurs and tyrannosaurs to have other traits of the hindlimb in common as well. Both groups had a pinched third metatarsal, called an arctometatarsus, that strengthened the foot. Holtz concluded that these traits indicated that tyrannosaurids were among the best adapted for running of all carnivorous dinosaurs.[19]
Erickson and Olson others calculated the bite force of T. rex, finding it to have some of the strongest jaws of any carnivorous vertebrate. By contrast, other carnivorous dinosaurs like Allosaurus had relatively weak jaws.[19]
Richard Cifelli and others reported teeth from Utah that exhibited the distinctive thickening characterizing tyrannosaurid teeth that date back to the Albian-Cenomanian boundary. As such, they were the oldest known tyrannosaurid teeth.[18]
Kirkland and others reported teeth from Utah that exhibited the distinctive thickening characterizing tyrannosaurid teeth that date back to the Albian-Cenomanian boundary. As such, they were the oldest known tyrannosaurid teeth.[18]
Sereno concluded that the evolutionary history of tyrannosaurids suggested a relatively complex history of biogeographic dispersal between Asia and North America.[18]
Horner and Dobb interpreted tyrannosaurids as scavengers.[11]
Sereno performed another phylogenetic analysis of the Tyrannosauridae and found additional support for reclassifying the family as coelurosaurs. He defined the tyrannosauridae as all tyrannosauroids closer to Tyrannosaurus than to Alectrosaurus, Aublysodon, or Nanotyrannus.[10]
Catherine Forster and others performed another phylogenetic analysis which provided further support for the idea that tyrannosaurs are coelurosaurs, but less closely related to birds than ornithomimosaurs.[10]
Peter Makovicky and Hans-Dieter Sues performed another phylogenetic analysis which provided further support for the idea that tyrannosaurs are coelurosaurs, but less closely related to birds than ornithomimosaurs.[10]
Karen Chin and others reported a coprolite preserved in the Frenchman Formation of Saskatchewan that may have been left behind by Tyrannosaurus. The coprolite contained the partially digested bone fragments of the ornithischian dinosaurs it fed upon.[18] These bones composed 30–50% of its total volume.[19]
Holtz found that within the coelurosaurs, tyrannosaurs were arctometatarsalians. In other words, they were more closely related to the ornithomimosaurs than to birds.[10]
Santanaraptor placidus.[12]Santanaraptor is a possible tyrannosauroid. If so, it is the only known member of the group that would have inhabited the super continent of Gondwana.[22]
Thomas Carr argued that Nanotyrannus was actually just a young Tyrannosaurus.[10] He noticed that adult T. rex had fewer and more widely spaced teeth in the front tip of their jaws than juvenile T. rex or tyrannosaurs of other species, suggesting differences in feeding within and between tyrannosaur species.[19]
Sereno performed another phylogenetic analysis of the Tyrannosauridae. He found that tyrannosaurs were closer to maniraptorans than Ornithomimosaurs were. He called the Tyrannosaur-Maniraptoran clade "
Günter P. Wagner and Gauthier performed a phylogenetic analysis of the tyrannosaurs but found them equally related to the ornithomimosaurs and maniraptorans.[10]
Carpenter reported a partially healed bite wound on a tail vertebra of an Edmontosaurus annectens, the size and shape of which suggested that it had been inflicted by Tyrannosaurus rex.[19]
Carr and Williamson observed that tyrannosaurines were the most common type of tyrannosaurid in the southwestern US during the Campanian and Maastrichtian.[18]
Phil Currie reported the discovery of at least nine Albertosaurus of different age groups preserved together in the same deposit. He speculated that if these animals were part of a social group, that members of different ages might perform different tasks in the course of a hunt. This interpretation derives by analogy from the behavior of modern pack hunting carnivorous mammals.[18]
Mark Norell and others found tyrannosaurids to lie outside of the Maniraptoriformes. In other words, they are less closely related to birds than the ostrich dinosaurs are.[10]
Thomas Lehman observed that during the Campanian and Maastrichtian the distribution of albertosaurines and tyrannosaurines was strongly correlated with the distributions of their respective ornithischian prey.[18]
David Varrichio and others reported a Daspletosaurus specimen from the Two Medicine Formation of Montana. This specimen notably preserved the contents of the animal's gut when it died, including fragments of bone from young ornithischian dinosaurs.[18]
Foster and others observed that no other theropod inhabiting Asia or North America during the Campanian or Maastrichtian achieved a body size within "two orders of magnitude" of contemporary tyrannosaurs.~paleobio133-134~ They further speculated that this gap in body size may be attributable to juvenile tyrannosaurs occupying the ecological niches once exploited by other medium-to-large sized theropods.[18]
Holtz found that within the coelurosaurs, tyrannosaurs were arctometatarsalians; meaning they were closer to ornithomimosaurs than to birds.[10]
recent common ancestor with it than with Aublysodon."[27]
Holtz considered these definitions only tentative due to the scant remains representing most taxa in the Aublysodontinae.
sexual morph of another kind of tyrannosaur.[29] Holtz also expressed the taxonomic opinion that Nanotyrannus lancensis was a juvenile T. rex.[10]
The results of his phylogenetic analysis of the Tyrannosauridae are reproduced below:
William L. Abler studied tyrannosaur tooth serration biomechanics.
tooth serrations are so thin that they are practically a shallow crack in the tooth.[30] However, at the base of each serration is round void called an ampulla which would have functioned to distribute force over a larger surface area, hindering the ability of the "crack" formed by the serration to propagate through the tooth.[30] This form resembles techniques used by guitar makers to "impart alternating regions of flexibility and rigidity" to wood.[31] As a proof of concept demonstrated that a plexiglass bar bearing regular incisions ending in drilled holes was more than 25% stronger than one with only regularly placed incisions.[32] Abler interpreted tyrannosaurid teeth as holdfasts for pulling meat off a body, rather than knife-like cutting implements.[33]
formation's tyrannosaurids, like Gorgosaurus, Daspletosaurus, or Aublysodon.[36] All of the marks on the jawbone seem to have been left by the same animal because the serration marks all share the same morphology.[37]
Brochu observed that the only distinguishing character of Aublysodon was the lack of serrations on its teeth, and that this condition might actually be due to damage sustained after the death of the animal. As such, he deemed that Aublysodon made a poor choice of anchor taxon for the Tyrannosauridae.[10]
Farlow and Holtz published a study concluding that the ancient ecology of tyrannosaur habitats and morphology of tyrannosaur bodies were inconsistent with the idea that they were scavengers.[19]
Holtz published a study concluding that the ancient ecology of tyrannosaur habitats and morphology of tyrannosaur bodies were inconsistent with the idea that they were scavengers.[19] He also suggested that the tyrannosaur skull was subjected to greater torsional forces hunting and/or feeding than the skulls of other large carnivorous dinosaurs like allosaurs and ceratosaurs. He interpretd the breadth of the tyrannosaur skull and high development of its secondary palate as adaptations for enduring these forces.[19] He theorized that tyrannosaurids exploited a similar hunting tactic to modern wolves and hyenas by running after prey and attacking it with their jaws. This tactic would distinguish tyrannosaurid hunting behavior from that of modern big cats, who depend more heavily on their forelimbs to take down prey.[19]
Carrano and Hutchinson tried to reconstruct the life musculature of T. rex.[19]
Hutchinson and Garcia used the reconstruction of T. rex musculature produced by Carrano and Hutchinson to ascertain its running abilities. They found that T. rex was not muscular enough for its body size to run quickly.[19]
Currie interpreted Nanotyrannus lancensis as a juvenile T. rex.[10] Currie argued that the type specimen of Alectrosaurus olseni was too incomplete to ascertain its position in the tyrannosaur family tree.[10]
paleoneurological description of Dilong paradoxus, comparing it with large tyrannosaurids, will be published by Kundrát et al. (2019).[60]
A study on the agility and turning capability of tyrannosaurids and other large theropods is published by Snively et al. (2019), who argue that tyrannosaurids could turn with greater agility, thus pivoting more quickly, than other large theropods, which enhanced their ability to pursue and subdue prey.[61]
A study on the tooth replacement patterns in tyrannosaurid theropods, as indicated by data from a juvenile specimen of Tarbosaurus bataar, will be published by Hanai & Tsuihiji (2019).[62]
A study on the complexity and modularity of the skull of Tyrannosaurus rex is published by Werneburg et al. (2019).[63]
Traces preserved on a tail vertebra of a
Upper Cretaceous Hell Creek Formation (Montana, United States) are described by Peterson & Daus (2019), who interpret their finding as feeding traces produced by a late-stage juvenile Tyrannosaurus rex.[64]
A large specimen of Tyrannosaurus rex (RSM P2523.8) with an estimated body mass exceeding other known T. rex specimens and representatives of all other gigantic terrestrial theropods is described by Persons, Currie & Erickson (2019).[65]
The tyrannosaur Suskityrannus originally found 1998 in the Moreno Hill Formation was described in May 2019. The genus serves as a gap between the smaller tyrannosaurids and the larger ones.[66]
Voris and others describe a juvenile Daspletosaurus postorbital and reidentify the only juvenile Daspletosaurus skeleton (TMP 1994.143.1) as a juvenile Gorgosaurus[67].
^ abMayor (2005); "Smoking the Monster's Bone: An Ancient Delaware Fossil Legend," pages 68–69.
^Horner (2001); "History of Dinosaur Collecting in Montana," page 44.
^For the implications of Dryptosaurus for theropod gait, see Holtz (2004); "Introduction", page 111. For a characterization of the Crystal Palace theropods, see Bakker (2004); page 3.
^For the discovery of T. rex, see Horner (2001); "History of Dinosaur Collecting in Montana," page 48. For the erection of the Tyrannosauridae, see Holtz (2004); "Introduction", page 114.
Abler, W. L. (2001). "A kerf-and-drill model of tyrannosaur tooth serrations". In Tanke, D. H.; Carpenter, K. (eds.). Mesozoic Vertebrate Life. Life of the Past. Indiana University Press. pp. 84–89.
Bakker, R. T. (2004). "Dinosaurs acting like birds, and vice versa – an homage to the Reverend Edward Hitchcock, first director of the Massachusetts Geological Survey". In Currie, P. J.; Koppelhus, E. B.; Shugar, M. A.; Wright, J. L. (eds.). Feathered Dragons. Life of the Past. Bloomington: Indiana University Press. pp. 1–11.
Brett-Surman, M. K. (1999). "Appendix: A Chronological History of Dinosaur Paleontology". In Farlow, J.O.; Brett-Surman, M.K. (eds.). The Complete Dinosaur. Indiana University Press. pp. 707–720.
Carpenter, K.; Miles, C.; Cloward, K. (2005). "New small theropod from the Upper Jurassic Morrison Formation of Wyoming". In Carpenter, K. (ed.). The Carnivorous Dinosaurs. Life of the Past. Indiana University Press. pp. 23–48.
Carpenter, K.; Smith, M. (2001). "Forelimb osteology and biomechanics of Tyrannosaurus rex". In Tanke, D. H.; Carpenter, K. (eds.). Mesozoic Vertebrate Life. Life of the Past. Indiana University Press. pp. 90–116.
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): 1–16.
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): 119–143.
Thomas D. Carr, Thomas E. Williamson, Brooks B. Britt and Ken Stadtman (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): 241–246.
Holtz, T. R. (2001). "The phylogeny and taxonomy of the Tyrannosauridae". In Tanke, D. H.; Carpenter, K. (eds.). Mesozoic Vertebrate Life. Life of the Past. Indiana University Press. pp. 64–83.
Horner, John R. (2001). Dinosaurs Under the Big Sky. Mountain Press Publishing Company.
David W. E. Hone, Kebai Wang, Corwin Sullivan, Xijin Zhao, Shuqing Chen, Dunjin Li, Shuan Ji, Qiang Ji and Xing Xu (2011). "A new, large tyrannosaurine theropod from the Upper Cretaceous of China". Cretaceous Research. 32 (4): 495–503.
Jacobsen, A. R. (2001). "Tooth-marked small theropod bone: An extremely rare trace". In Tanke, D. H.; Carpenter, K. (eds.). Mesozoic Vertebrate Life. Life of the Past. Indiana University Press. pp. 58–63.
Sereno, P.; Tan, L.; Brusatte, S. L.; Kriegstein, H. J.; Zhao, X. & Cloward, K. (2009). "Tyrannosaurid skeletal design first evolved at small body size".
Tanke, D. H. (2010). "Lost in plain sight: rediscovery of William E. Cutler's missing Eoceratops". In Ryan, M. J.; Chinnery-Allgeier, B. J.; Eberth, D. A. (eds.). New Perspectives on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian Symposium. Life of the Past. Bloomington: Indiana University Press. pp. 541–550.