Timeline of ornithomimosaur research

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,[1] 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.[2] Thus the ornithomimid ornithomimosaurs were one of the first major Mesozoic theropod groups to be recognized in the fossil record.[3] The description of a second ornithomimosaur genus did not happen until nearly 30 years later, when Henry Fairfield Osborn described Struthiomimus in 1917.[2] 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.[3] More Asian discoveries took place even later in the 20th century, including the disembodied arms of Deinocheirus mirificus and the new genus Gallimimus bullatus.[3] The formal naming of the Ornithomimosauria itself was performed by Rinchen Barsbold in 1976.[2]

Early research into ornithomimosaur evolution was based on comparative anatomy.[2] 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.[3] Subsequent research and discoveries during the 1990s refined science's knowledge of ornithomimosaur evolution.[2] 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.[3]

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.[4] 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.[5]

19th century

Holotype material of Ornithomimus velox

1860s

1865

1890s

1890

1892

20th century

Cast of a Struthiomimus altus skeleton at the Royal Ontario Museum

1900s

1902

1910s

An early restoration of S. altus published in a 1921 issue of the magazine Natural History

1917

1920s

1920

1926

1928

1930s

Skeletal mount of "Ornithmomimus" (now Archaeornithomimus) asiaticus

1933

1960s

1960

1965

1970s

Holotype of Deinocheirus mirificus on display

1970

1972

Life restoration of Gallimimus

1976

1980s

1981

1982

1984

Artistic restoration of Harpymimus okladnikovi

1985

1988

1990s

The beaks of ornithomimosaurs had deeper tips than ratites like the skull this ostrich.

1990

1991

1993

Estimated size of Pelecanimimus, compared to a human
The femur of Timimus

1994

1995

1997

1998

Artistic restoration of Elaphrosaurus bambergii.

1999

21st century

Skull of Gallimimus

2000s

2001

2002

2003

2006

2009

2010s

Skeletal mount of Beishanlong

2010

2011

2012

Artist's restoration of Deinocheirus

2014

2016

See also

Footnotes

  1. 1 2 3 4 5 6 7 8 Makovicky, Kobayashi, and Currie (2004); "Table 6.1: Ornithomimosauria", page 139.
  2. 1 2 3 4 5 6 Makovicky, Kobayashi, and Currie (2004); "Introduction", page 137.
  3. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 Makovicky, Kobayashi, and Currie (2004); "Systematics and Evolution", page 146.
  4. 1 2 3 4 5 6 7 8 9 10 Makovicky, Kobayashi, and Currie (2004); "Paleobiology", page 149.
  5. Makovicky, Kobayashi, and Currie (2004); "Paleobiology", pages 149-150.
  6. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Makovicky, Kobayashi, and Currie (2004); "Table 6.1: Ornithomimosauria", page 138.
  7. 1 2 3 4 Makovicky, Kobayashi, and Currie (2004); "Systematics and Evolution", page 147.
  8. 1 2 3 4 5 6 7 8 Makovicky, Kobayashi, and Currie (2004); "Paleobiology", page 150.
  9. For date, see Khan (2014). For expedition, see Lee et al. (2014); "Abstract," page 257.
  10. 1 2 3 4 5 Makovicky, Kobayashi, and Currie (2004); "Systematics and Evolution", page 148.
  11. Makovicky, Kobayashi, and Currie (2004); "Biogeography", page 149.
  12. 1 2 Hurum (2001); "Abstract," page 34.
  13. Hurum (2001); "Abstract," page 35.
  14. Hurum (2001); "Conclusions," page 40.
  15. 1 2 For date and catalogue number, see Lee et al. (2014); "Abstract," page 257. For expedition, see Hecht (2014).
  16. 1 2 Khan (2014).
  17. Buffetaut, Suteethorn, and Tong (2009); "Abstract", page 229.
  18. Makovicky et al. (2010); "Abstract", page 191.
  19. 1 2 3 Hecht (2014); "Fossil smugglers".
  20. Joyce (2014).
  21. Jiji (2014).
  22. Xu et al. (2011); "Abstract", page 213.
  23. Jin, Chen, and Godefroit (2012); "Abstract", page 467.
  24. Lee et al. (2014); "Abstract," page 257.

References

External links

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