Timeline of tyrannosaur research
This timeline of tyrannosaur research is a chronological listing of events in the history of paleontology focused on the tyrannosaurs, a group of predatory theropod dinosaurs that began as small, long-armed bird-like creatures with elaborate cranial ornamentation but achieved apex predator status during the Late Cretaceous as their arms shrank and body size expanded. Although formally trained scientists did not begin to study tyrannosaur fossils until the :Category:19th century in paleontology|mid-19th century, these remains may have been discovered by Native Americans and interpreted through a mythological lens. The Montana Crow tradition about thunder birds with two claws on their feet may have been inspired by isolated tyrannosaurid forelimbs found locally. Other legends possibly inspired by tyrannosaur remains include Cheyenne stories about a mythical creature called the Ahke, and Delaware stories about smoking the bones of ancient monsters to have wishes granted.
Tyrannosaur remains were among the first dinosaur fossils collected in the United States. The first of these was named Deinodon horridus by Joseph Leidy. However, as this species was based only on teeth the name would fall into disuse. Soon after, Edward Drinker Cope described Laelaps aquilunguis from a partial skeleton in New Jersey. Its discovery heralded the realization that carnivorous dinosaurs were bipeds, unlike the lizardlike megalosaurs sculpted for the Crystal Palace. Laelaps was also among the first dinosaurs to be portrayed artistically as a vigorous, active animal, presaging the Dinosaur Renaissance by decades. 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.
Early in the :Category: 20th century in paleontology|20th century, Tyrannosaurus itself was discovered by Barnum Brown and named by Henry Fairfield Osborn, who would recognize it as a representative of a distinct family of dinosaurs he called the Tyrannosauridae. Tyrannosaur taxonomy would be controversial for many decades afterward. One controversy centered around the use of the name Tyrannosauridae for this family, as the name "Deinodontidae" had already been proposed. The name Tyrannosauridae came out victorious following arguments put forth by Dale Russell in 1970. The other major controversy regarding tyrannosaur taxonomy was the family's evolutionary relationships. Early in the history of paleontology, it was assumed that the large carnivorous dinosaurs were all part of one evolutionary lineage, while the small carnivorous dinosaurs were part of a separate lineage. 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 :Category:1990s in paleontology|1990s, when the application of cladistics to tyrannosaur systematics confirmed the doubts of early workers and found tyrannosaurs to be large-bodied coelurosaurs.
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 Tyrannosaurus that some, like Lawrence Lambe, were skeptical that it was even capable of hunting down live prey and assumed that it lived as a scavenger. This view continued to be advocated into the 1990s by 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.
Prescientific
- The Delaware people of what is now New Jersey or Pennsylvania had a tradition regarding a hunting party that returned with a piece of an ancient bone supposedly belonging to a monster that killed humans. One of the village's wise men instructed people to burn bits of the bone in clay spoons with tobacco and make a wish while the concoction was still smoking. This ritual could bestow such favors as success in hunting, long life, and health for one's children. This tale might be inspired by local fossils, which include Dryptosaurus, ankylosaurs, Coelosaurus, and Hadrosaurus.
- The Cheyenne believed that a mythical creature called an Ahke once lived in the prairies of the western United States. These creatures were thought to resemble giant buffalo, whose bones turned to stone. Ahke bones were found both on land as well as buried in the banks of streams. Tyrannosaurus fossils preserved in Hell Creek Formation strata may have been influences on this old legend. Its contemporary Triceratops is another possible influence, as well as the more recent Cenozoic fossils of Titanotherium and mastodons.
19th century
1850s
1856- Joseph Leidy described the new genus and species Deinodon horridus.
1860s
- Leidy described the new genus and species Tomodon horrificus.
- Edward Drinker Cope described the new genus and species Laelaps aquilunguis. This discovery proved that theropod dinosaurs walked on their hind limbs rather than on all fours like in earlier reconstructions. He also erected the family Deinodontidae.
- Leidy described the new genus and species Aublysodon mirandus.
- Leidy described the new genus Diplotomodon for the species Tomodon horrificus.
- Cope described the new species Laelaps macropus.
1870s
- Cope described the new species Laelaps incrassatus and Laelaps falculus. He also described Aublysodon lateralis.
- Cope described the new species Laelaps hazenianus.
- Othniel Charles Marsh described the new genus Dryptosaurus to house the species Laelaps aquilunguis.
1880s
- Joseph Burr Tyrrell discovered a partial Albertosaurus skull near Kneehills Creek in Alberta, Canada. This specimen is now catalogued as CMN 5600.
1890s
- Marsh described the new species Ornithomimus grandis.
- Cope described the new genus and species Manospondylus gigas.
- Marsh described the new species Aublysodon amplus and A. cristatus.
- Oliver Perry Hay described the new species Dryptosaurus kenabakides.
20th century
1900s
1900- Barnum Brown found a partial skeleton of Tyrannosaurus in eastern Wyoming.
- Barnum Brown found a substantially complete skeleton of Tyrannosaurus in the Hell Creek Formation of Montana.
- Henry Fairfield Osborn named the Tyrannosauridae. Osborn described the new genus and species Albertosaurus sarcophagus. Osborn described the new genus and species Tyrannosaurus. Osborn described the new genus and species Dynamosaurus imperiosus.
1910s
- Lawrence Lambe described the new genus and species Gorgosaurus libratus.
- Barnum Brown emended Cope's "Dinodontidae" to "Deinodontidae".
- Lambe interpreted tyrannosaurids as scavengers.
1920s
- Matthew and Brown named the Tyrannosaurinae. Despite still classifying tyrannosaurs as members of the family Deinodontidae, they proposed that, contrary to researchers who regarded tyrannosaurs as carnosaurs related to other large carnivorous dinosaurs like Allosaurus and Megalosaurus, the tyrannosaurs were actually more closely related to the small carnivores known as coelurosaurs.
1923
- Matthew and Brown described the new species
- William Parks described the new species
1930s
1930- Anatoly Nikolaevich Riabinin described the new species Albertosaurus periculosus.
- Von Huene classified tyrannosaurs as carnosaurs.
- Charles Whitney Gilmore described the new genus and species Alectrosaurus olseni.
1940s
- Gilmore described the new species Gorgosaurus lancensis.
1950s
- Colbert classified tyrannosaurs as carnosaurs.
- Evgeny Maleev described the new genus and species Tarbosaurus bataar. He also described the species T. efremovi. He also described the species Gorgosaurus lancinator.
- Maleev described the new species of Maleevosaurus, Albertosaurus, Aublysodon, Deinodon novojilovi.
- Alfred Sherwood Romer classified tyrannosaurs as carnosaurs.
- Young described the new genus and species Chingkankosaurus fragilis.
1960s
- Walker named the Tyrannosauroidea. He regarded tyrannosaurs as carnosaurs.
1970s
- Dale Russell described the new genus and species Daspletosaurus torosus. He classified it in the family Tyrannosauridae rather than the historical home of tyrannosaurs, the Deinodontidae, setting a trend among paleontologists that would see the latter familial name fall into disuse in favor of the former. He observed that Daspletosaurus and Gorgosaurus lived at the same time and place, while Daspletosaurus was less common. He also noticed that hadrosaurs and ceratopsians were both present in the same deposits, with ceratopsians being less common. He speculated that this parallel may have been due to niche partitioning between the tyrannosaurs as each specialized in prey, with the lighter built and more common Gorgosaurus feeding on hadrosaurs and the more rugged and less common Daspletosaurus specializing in the rarer and more dangerous ceratopsians. He noted that while adult tyrannosaurs may have fed on such large prey, very young individuals would be limited to quarry like birds, frogs, mammals, and small reptiles.
- Rodney Steel classified tyrannosaurs as carnosaurs.
- Madsen described the new genus and species Stokesosaurus clevelandi. This is the oldest known tyrannosauroid.
- Maleev still classified tyrannosaurs in the family Deinodontidae.
- Ralph Molnar described the new genus and species
1976
- Sergei Mikhailovich Kurzanov described the new genus and species
- Dong described the new genus and species
- Paul Colinvaux interpreted tyrannosaurids as scavengers.
- Dong described the new genus and species
1980s
1980- Halszka Osmólska reported multiple Tarbosaurus of different life stages found preserved together in the same deposit.
- Lambert Beverly Halstead and his wife Jennifer Middleton interpreted tyrannosaurids as scavengers.
1983
- Rinchen Barsbold interpreted tyrannosaurids as scavengers.
- Jacques Gauthier classified tyrannosaurs as carnosaurs.
- 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.
- Bakker described the new genus
1990s
1990- José Bonaparte and others classified tyrannosaurs as carnosaurs.
- Molnar classified tyrannosaurs as carnosaurs.
- Sue, catalog name FMNH PR 2081, the largest and most complete T.rex skeleton yet found, discovered on August 12, 1990 on the Cheyenne River Indian Reservation in South Dakota.
- 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.
- Scotty the T.Rex is discovered near Eastend, Saskatchewan.
- Kenneth Carpenter described the new genus Maleevosaurus.
- William Abler studied tyrannosaur tooth biomechanics. He concluded that the serrations on tyrannosaur teeth did not function like the serrations on a saw blade. Instead he thought the serrations may have caught pieces of rotting meat inside them, sustaining bacterial colonies that make its bite likely to transmit deadly infections to potential prey items. Similar use of decaying meat trapped in tooth serrations as a vector for infected prey had been reported in monitor lizards.
- Fernando Emilio Novas performed a phylogenetic analysis of the tyrannosauridae, finding tyrannosaurs to actually be coelurosaurs, as advocated by a few contrarian workers during the 1920s, rather than carnosaurs as had been generally supposed for decades. Novas found them equally related to the ornithomimosaurs and maniraptorans.
- Bernardino Pérez Pérez-Moreno and others performed another phylogenetic analysis of the Tyrannosauridae and found additional support for reclassifying the family as coelurosaurs. They found that within the coelurosaurs, tyrannosaurs were arctometatarsalians. In other words, they were more closely related to the ostrich dinosaurs than to birds.
- Farlow found that the ancient ecology of tyrannosaur habitats were inconsistent with the idea that they were scavengers.
- Horner and Donald Lessem interpreted tyrannosaurids as scavengers.
- Pérez-Moreno and others performed another phylogenetic analysis of the Tyrannosauridae and found additional support for reclassifying the family as coelurosaurs. They found tyrannosaurids to lie outside of the maniraptoriformes. In other words, they are less closely related to birds than the ostrich dinosaurs are.
- Thomas Holtz performed another phylogenetic analysis of the Tyrannosauridae and found additional support for reclassifying the family as coelurosaurs. He found that within the coelurosaurs, tyrannosaurs were arctometatarsalians. In other words, they were more closely related to the ostrich dinosaurs than to birds.
- Horner interpreted tyrannosaurids as scavengers.
- Martin Lockley and Hunt described a possible Tyrannosaurus footprint.
- 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.
- 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.
- 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
- Osmólska described the new genus and species
- 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.
- 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.
- Sereno concluded that the evolutionary history of tyrannosaurids suggested a relatively complex history of biogeographic dispersal between Asia and North America.
- Horner and Dobb interpreted tyrannosaurids as scavengers.
- 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
- 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. These bones composed 30–50% of its total volume.
- Holtz found that within the coelurosaurs, tyrannosaurs were arctometatarsalians. In other words, they were more closely related to the ornithomimosaurs than to birds.
- Alexander Kellner described the new genus and species Santanaraptor placidus. 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.
- Thomas Carr argued that Nanotyrannus was actually just a young Tyrannosaurus. 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.
- Sereno performed another phylogenetic analysis of the Tyrannosauridae. He found that tyrannosaurs were maniraptorans.
- Günter P. Wagner and Gauthier performed a phylogenetic analysis of the tyrannosaurs but found them equally related to the ornithomimosaurs and maniraptorans.
21st century
2000s
2000- Oliver Walter Mischa Rauhut reported the presence of Stokesosaurus or an extremely close relative in Portugal.
- 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.
- Carr and Williamson observed that tyrannosaurines were the most common type of tyrannosaurid in the southwestern US during the Campanian and Maastrichtian.
- 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.
- Darren Tanke and Currie reported that many specimens of Gorgosaurus and Daspletosaurus preserve evidence of bite wounds inflicted by members of the same tyrannosaur species. This is suggestive of face biting behavior of the sort seen in many kinds of modern predator like crocodilians, monitor lizards, and wolves.
- 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.
- Stephen Hutt and others described the new genus and species
Holtz considered these definitions only tentative due to the scant remains representing most taxa in the Aublysodontinae. Holtz also noted that the lack of serrations on aublyodontines' premaxillary teeth could have been caused by tooth wear in life, postmortem abrasion, or digestion. Alternatively "Aublysodontine"-type teeth could be from an ontogenetic stage or sexual morph of another kind of tyrannosaur. Holtz also expressed the taxonomic opinion that Nanotyrannus lancensis was a juvenile T. rex. The results of his phylogenetic analysis of the Tyrannosauridae are reproduced below:
- William L. Abler studied tyrannosaur tooth serration biomechanics. He observed that Albertosaurus tooth serrations are so thin that they are practically a shallow crack in the tooth. 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. . This form resembles techniques used by guitar makers to "impart alternating regions of flexibility and rigidity" to wood. 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. Abler interpreted tyrannosaurid teeth as holdfasts for pulling meat off a body, rather than knife-like cutting implements.
- A. R. Jacobsen published a description of a dentary referred to Saurornitholestes with tooth marks. The specimen was preserved in the Dinosaur Park Formation. Although a specific identification cannot be made, the shape of the preserved serration marks implicate a juvenile individual of one of the formation's tyrannosaurids, like Gorgosaurus, Daspletosaurus, or Aublysodon. 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.
- 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.
- 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.
- 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. 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. 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.
- Carrano and Hutchinson tried to reconstruct the life musculature of T. rex.
- 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.
- Hunt coined the name "Fusinasus".
2003
- Currie interpreted Nanotyrannus lancensis as a juvenile T. rex. Currie argued that the type specimen of Alectrosaurus olseni was too incomplete to ascertain its position in the tyrannosaur family tree.
- Rauhut described the new genus and species Aviatyrannis.
- Xu and others described the new genus and species Dilong paradoxus.
- T. D. Carr, T. E. Williamson, D. R. Schwimmer described the new genus and species Appalachiosaurus.
- K. Carpenter, C. Miles, and K. Cloward described the new genus and species
- Xu and others described the new genus and species
- Sereno et al. described the new genus and species
2010s
2010- Carr and Williamson described the new genus and species Bistahieversor sealeyi.
- Averianov and others, described the new genus and species Kileskus aristotocus.
- Li and others, described the new genus and species Xiongguanlong baimoensis.
- Carr and others described the new genus and species Teratophoneus curriei.
- Hone and others described the new genus and species
- Xu and others described the new genus and species
- Brusatte and Benson described the new genus and species
Cladogram of tyrannosaurs from Loewen et al. 2013
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2014
- Fiorillo and Tykoski described the new genus and species
- The National Geographic Channel aired a documentary,
- Brusatte and others described the new genus and species
- Brusatte and others described the new species
- McDonald and others described the new genus and species
- Zanno and others described the new genus and species
2020s
2020- Wu and others described the new genus and species Jinbeisaurus wangi.
- Voris and others describe Thanatotheristes degrootorum.
Footnotes