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 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 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 ("carnosaurs"), while the small carnivorous dinosaurs were part of a separate lineage (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.

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

1865 Leidy described the new genus and species Tomodon horrificus.

1866 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.

1868 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

1876 Cope described the new species Laelaps incrassatus and Laelaps falculus. He also described Aublysodon lateralis. Cope described the new species Laelaps hazenianus.

1877 Othniel Charles Marsh described the new genus Dryptosaurus to house the species Laelaps aquilunguis.

1880s

1884 Joseph Burr Tyrrell discovered a partial Albertosaurus skull near Kneehills Creek in Alberta, Canada. This specimen is now catalogued as CMN 5600.

1890s

1890 Marsh described the new species Ornithomimus grandis.

1892 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.

1902 Barnum Brown found a substantially complete skeleton of Tyrannosaurus in the Hell Creek Formation of Montana.

1905 Henry Fairfield Osborn named the Tyrannosauridae. Osborn described the new genus and species Albertosaurus sarcophagus. Osborn described the new genus and species Tyrannosaurus rex. Osborn described the new genus and species Dynamosaurus imperiosus.

1910s

1914 Lawrence Lambe described the new genus and species Gorgosaurus libratus. Barnum Brown emended Cope's "Dinodontidae" to "Deinodontidae".

1917 Lambe interpreted tyrannosaurids as scavengers.

1920s

1922 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 Gorgosaurus sternbergi. They still regarded tyrannosaurs as members of the family Deinodontidae. Friedrich von Huene regarded tyrannosaurs as members of the family Deinodontidae 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.

1928 William Parks described the new species Albertosaurus arctunguis.

1930s

1930 Anatoly Nikolaevich Riabinin described the new species Albertosaurus periculosus.

1932 Von Huene classified tyrannosaurs as carnosaurs.

1933 Charles Whitney Gilmore described the new genus and species Alectrosaurus olseni.

1940s

1946 Gilmore described the new species Gorgosaurus lancensis.

1950s

1955 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.

1956 Alfred Sherwood Romer classified tyrannosaurs as carnosaurs.

1958 Young described the new genus and species Chingkankosaurus fragilis.

1960s

1964 Walker named the Tyrannosauroidea. He regarded tyrannosaurs as carnosaurs.

1970s

1970 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.

1974 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 Labocania anomala.

1975

1976 Sergei Mikhailovich Kurzanov described the new genus and species Alioramus remotus as well as the new genus and species Itemirus medullaris.

1977 Dong described the new genus and species Shanshanosaurus huoyanshanensis.

1978 Paul Colinvaux interpreted tyrannosaurids as scavengers.

1979 Dong described the new genus and species Tyrannosaurus luanchuanensis.

1980s

1980 Halszka Osmólska reported multiple Tarbosaurus of different life stages found preserved together in the same deposit.

1981 Lambert Beverly Halstead and his wife Jennifer Middleton interpreted tyrannosaurids as scavengers.

1983 Rinchen Barsbold interpreted tyrannosaurids as scavengers.

1986 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.

1988 Bakker described the new genus Nanotyrannus lancensis to house the species Gorgosaurus lancensis. Gregory S. Paul described the new species Albertosaurus megagracilis and Aublysodon molnari.

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 found at the time, discovered on August 12, 1990 on the Cheyenne River Indian Reservation in South Dakota.Chicago Field Museum - All About Sue

1991 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.

1992 Kenneth Carpenter described the new genus Maleevosaurus.