page_title: Timeline of dromaeosaurid research
section_title: 1990s
hierarchical_section_title: Timeline of dromaeosaurid research / 20th century / 1990s
caption_attribution_description: Size chart for Utahraptor ostrommaysorum. Proportions follow the related Achillobator. Figure scaled based on the specimen BYU 15465. Erickson, Rauhut, Zhou, Turner, Inouye, Hu and Norell, 2009. Was dinosaurian physiology inherited by birds? Reconciling slow growth in Archaeopteryx. PLoS ONE. 4(10), e7390. doi:10.1371/journal.pone.0007390
context_page_description: This timeline of dromaeosaurid research is a chronological listing of events in the history of paleontology focused on the dromaeosaurids, a group of sickle-clawed, bird-like theropod dinosaurs including animals like Velociraptor. Since the Native Americans of Montana used the sediments of the Cloverly Formation to produce pigments, they may have encountered remains of the dromaeosaurid Deinonychus hundreds of years before these fossils came to the attention of formally trained scientists.
  In 1922 Matthew and Brown named the new genus and species Dromaeosaurus albertensis, considering it a new type within the family Deinodontidae, a now-defunct family name that once applied to the tyrannosaurs. Not long after, Velociraptor was discovered in Mongolia by the Central Asiatic Expedition. Dromaeosaur research was fairly quiet until the 1960s, when John Ostrom described the new genus and species Deinonychus antirrhopus. This discovery played a major role in setting off the Dinosaur Renaissance because Deinonychus was obviously a vigorous, active animal, and exhibited characteristics linking it to the origin of birds.
context_section_description: 1990
  Ostrom published further arguments building a case for a close evolutionary relationship between dromaeosaurids and birds.
  1993
  Kirkland, Burge, and Gaston described the new genus and species Utahraptor ostrommaysi.
  Osmolska challenged Kielan-Jaworowska and Barsbold's 1972 interpretation of an associated skeleton of Velociraptor and Protoceratops as being of two animals killed and preserved while locked in mortal combat. She reinterpreted the association as a Velociraptor that had been killed while scavenging an already dead Protoceratops.
  1994
  Ostrom speculated that Deinonychus hunted in packs to subdue prey larger than itself based on an association between several Deinonychus skeletons and a specimen of the ornithopod Tenontosaurus.
  1995
  Currie followed Barsbold's division of Dromaeosauridae into Dromaeosaurinae and Velociraptorinae. However, he proposed differing definitions for these subfamilies and argued that they had different members than were included under Barsbold's classification scheme.
  Maxwell and Ostrom reported on the association of Deinonychus teeth and Tenontosaurus remains and argued that these provided further support for the hypothesis that Deinonychus was a pack hunter.
  Unwin and others followed the fighting-to-the-death interpretation of the fighting dinosaurs specimen.
  1997
  Novas and Puerta described the new genus and species Unenlagia comahuensis.
  Chatterjee argued that dromaeosaurids lived in trees based on the anatomy of their hands and the backward orientation of the pubic bones in their pelvis.
  Reid examined histological sections of the bones of Saurornitholestes to see whether or not they were consistent with the idea that dromaeosaurids were warm blooded. However, the results of his study were inconclusive.
  Ruben and others attempted to reconstruct the way air would flow through the snouts of dromaeosaurids during respiration to see whether or not it was consistent with the airflow patterns of modern cold or warm-blooded animals. They found that the probable course of airflow through the snout of a living, breathing dromaeosaurid would have been more consistent with that of a cold blooded animal. However, the anatomical reconstructions the researchers used to draw these conclusions have been criticized for positioning the choana too far forward and for excluding the animals' secondary palate.
  1998
  Le Leouff and Buffetaut described the new genus and species Variraptor mechinorum.
  Novas described the new genus and species Megaraptor namunhuaiquii.
  D. L. Brinkman and others reinterpreted the association between several Deinonychus specimens and a Tenontosaurus as preserving the aftermath of an ancient feeding frenzy rather than as evidence of pack hunting behavior in Deinonychus as argued by Ostrom.
  1999
  Clark and others argued that it was impossible to know whether or not Velociraptor was a predator of Protoceratops based on the famous "fighting dinosaurs" specimen, since this was only one specimen.
  Altangerel Perle, Norell and Clark described the new genus and species Achillobator giganticus.
  Xu, Wang, and Wu described the new genus and species Sinornithosaurus millenii. The specimen actually preserved the remains of the feathers that covered the animal in life. The presence of a feathery covering is consistent with the idea that dromaeosaurids were warm-blooded. They also performed a cladistic analysis of the Dromaeosauridae, finding more support for dividing the family into Dromaeosaurinae and Velociraptorinae. The researchers found both groups to be monophyletic clades, with Sinornithosaurus milenii the sister group to both, and therefore the most primitive known dromaeosaurid.
caption: Illustration of a Utahraptor with a human to scale
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