page_title: Timeline of tyrannosaur research
section_title: 2000s
hierarchical_section_title: Timeline of tyrannosaur research / 21st century / 2000s
caption_attribution_description: English: Pieces known from the theropod dinosaur Eotyrannus lengi (the holotype MIWG 1997.550).[1] The holotype are from a subadult, complete to abort 40&#160;%. Sources ↑ Martill D.M., Newbery P et.al. (2001), "A preliminary account of a new tyrannosauroid theropod from the Wessex Formation (Early Cretacous) of Southern England", Cretacous Research 22(2): p.227-242. Skull fragments. Skull fragments (compared with other coelurosaurs (Eotyrannus is H)). Humerus (upper arm bone). Partial skeletal diagram. Skeletal diagram. Skeletal diagram by Scott Hartman. More reading.
context_page_description: 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.
context_section_description: 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.
  2001
  Stephen Hutt and others described the new genus and species Eotyrannus lengi.
  Kenneth Carpenter and Matt Smith published a detailed description of the osteology and biomechanics of T. rex forelimbs. They concluded that T. rex arms were actually rather strong, but with a much smaller range of motion than other carnivorous dinosaurs like Allosaurus and Deinonychus. They concluded that while the arms of Tyrannosaurus would have been useless for actually killing prey, they may have been used to hold on to prey while the tyrannosaur killed it with bites. They dismissed notions that the forelimbs were useless or that Tyrannosaurus rex was an obligate scavenger. This study was the complete description of Tyrannosaurus forelimbs in the scientific literature.
  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.
  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.
  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.
  Holtz found that within the coelurosaurs, tyrannosaurs were arctometatarsalians; meaning they were closer to ornithomimosaurs than to birds.
  Thomas R. Holtz, Jr. published a cladistic analysis of the Tyrannosauridae. Holtz defined the Tyrannosauridae in his analysis as "all descendants of the most recent common ancestor of Tyrannosaurus and Aublysodon." He concluded that the Tyrannosauridae had two subfamilies, a more primitive Aublysodontinae and the tyrannosaurinae. He defined the former as "Aublysodon and all taxa sharing a more recent common ancestor with it than with Tyrannosaurus." 
   He observed that these dinosaurs were distinguished by their unserrated premaxillary teeth.  The Tyrannosaurinae he defined as "Tyrannosaurus and all taxa sharing a more recent common ancestor with it than with Aublysodon."
  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"
caption: Known skeletal elements of Eotyrannus lengi.
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