This timeline of ornithomimosaur research is a chronological listing of events in the history of paleontology focused on the ornithomimosaurs, a group of bird-like theropods popularly known as the ostrich dinosaurs. Although fragmentary, probable, ornithomimosaur fossils had been described as far back as the 1860s, the first ornithomimosaur to be recognized as belonging to a new family distinct from other theropods was Ornithomimus velox, described by Othniel Charles Marsh in 1890. Thus the ornithomimid ornithomimosaurs were one of the first major Mesozoic theropod groups to be recognized in the fossil record. The description of a second ornithomimosaur genus did not happen until nearly 30 years later, when Henry Fairfield Osborn described Struthiomimus in 1917. Later in the 20th century, significant ornithomimosaur discoveries began occurring in Asia. The first was a bonebed of "Ornithomimus" (now Archaeornithomimus) asiaticus found at Iren Debasu. More Asian discoveries took place even later in the 20th century, including the disembodied arms of Deinocheirus mirificus and the new genus Gallimimus bullatus. The formal naming of the Ornithomimosauria itself was performed by Rinchen Barsbold in 1976. Early research into ornithomimosaur evolution was based on comparative anatomy. In 1972, Dale Russell argued that the Jurassic Elaphrosaurus of Africa was an ancestral relative of ornithomimids. The descriptions of Garudimimus and Harpymimus in the 1980s revealed the existence of primitive ornithomimosaurs outside of the Ornithomimidae proper. Subsequent research and discoveries during the 1990s refined science's knowledge of ornithomimosaur evolution. In 1994, Pelecanimimus polyodon was described from Europe, the first known ornithomimosaur from that continent and apparently a very evolutionarily primitive taxon. From the late 1990s into the early 21st century cladistic evidence mounted against Russell's hypothesis that ornithomimosaurs were descended from a close relative of Elaphrosaurus, and favored an ancestry close to Pelecanimimus. Paleontologists found that within the theropod family tree, ornithomimosaurs were primitive coelurosaurs closely related to, but outside of, the maniraptorans. The juxtaposition of apparent evolutionary affinities to carnivorous dinosaurs with the possession of toothless beaks has led to controversy among paleontologists trying to reconstruct the diet of ornithomimosaurs. Osborn hypothesized in 1917 that ornithomimosaurs may have eaten plants, social insects, or aquatic invertebrates. In the 1970s paleontologists Russell, Halszka Osmolska, and her colleagues considered ornithomimosaurs carnivores that may have fed on insects, small vertebrates, or eggs. In the early to mid 1980s, however Russell and Elizabeth Nicholls began advocating a reinterpretation of ornithomimosaurs as herbivores. With the 1999 report of gastroliths in the new genus Sinornithomimus, came further support for reinterpreting ornithomimosaurs as herbivores or filter feeders rather than carnivores. In 2001, Mark Norell reported a comb-like structure in the beak of Gallimimus that may have been used for filter feeding, bringing renewed credibility to one of Osborn's 1917 hypotheses. If this interpretation of the evidence is correct, Gallimimus would be the largest terrestrial filter feeder in history.
19th century
1860s
1865 Joseph Leidy described the new species Coelosaurus antiquus.
1890s
1890 Othniel Charles Marsh described the new genus and species Ornithomimus velox. He also described the new species Ornithomimus tenuis and erected a new family to house them, the Ornithomimidae.
1892 Marsh described the new species Ornithomimus sedens.
20th century
1900s
1902 Lawrence Lambe described the new species Ornithomimus altus.
1910s
1917 Henry Fairfield Osborn reported the discovery of a more complete "Ornithomimus" altus specimen in Dinosaur Provincial Park, Alberta. He erected a new genus, Struthiomimus, for this species. Osborn put forth early speculations on the diet of ornithomimosaurs. He considered three possible diets: plants, social insects, and aquatic invertebrates.
1920s
1920 Charles Whitney Gilmore described the new species Coelosaurus affinis.
1926 William Arthur Parks described the new species Struthiomimus brevitertius.
1928 Parks described the new species Struthiomimus samueli.
1930s
1933 Gilmore described the new species Ornithomimus asiaticus. This was the first known ornithomimosaur to be discovered in Asia. The remains of multiple individuals were recovered from a bonebed at Iren Dabasu. Parks described the new species Struthiomimus currelli. Parks described the new species Struthiomimus ingens. Sternberg described the new species Ornithomimus edmontonicus.
1960s
1960 Lapparent described the new species Elaphrosaurus gautieri.
1965 July: The type specimen of the dinosaur that would later be named Deinocheirus mirificus was discovered by Polish–Mongolian Palaeontological Expedition in Mongolia.
1970s
1970 Osmolska and Roniewicz, and Barsbold described the new genus and species Deinocheirus mirificus.
1972 Russell published a review of the Late Cretaceous ornithomimids from North America. He also described the new genus Dromiceiomimus and classified two different species therein. Russell described the new genus Archaeornithomimus. Russell regarded a Late Jurassic theropod from Tanzania called Elaphrosaurus bambergi to be a primitive ornithomimosaur. This species would later be shown to be a coelophysoid. Russell concluded based on ornithomimid pelvic and leg anatomy that they could achieve similar running speeds to modern ostriches, but would not have been as maneuverable. He also observed that since the ornithomimosaur pelvic canal is wide compared to that of other dinosaur groups they may have laid only a few large eggs or even gave birth to live young.
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