Timeline of therizinosaur research

Reconstructed skeleton of the therizinosaur Nothronychus mckinleyi

This timeline of therizinosaur research is a chronological listing of events in the history of paleontology focused on the therizinosaurs, unusually long-necked, pot-bellied, and large-clawed herbivorous theropod dinosaurs closely related to birds. The early history of therizinosaur research occurred in three phases. The first phase was the discovery of scanty and puzzling fossils in Asia by the Central Asiatic Expeditions of the 1920s and Soviet-backed research in the 1950s. This phase resulted in the discovery of the Therizinosaurus cheloniformis type specimen. Soviet paleontologist Evgeny Maleev interpreted these unusual remains as belonging to some kind of gigantic turtle.[1]

The second major phase of therizinosaur research followed the discovery of better preserved remains in the 1970s by collaborative research between the Soviets and Mongolians. These finds revealed the true nature of therizinosaurs as bizarre dinosaurs.[1] However, the exact nature and classification of therizinosaurs within Dinosauria was controversial as was their paleobiology. When Rozhdestventsky first reinterpreted therizinosaurs as dinosaurs he argued that they were unusual theropods that may have used their clawed arms to break open termite mounds or collect fruit.[2] Osmolska and Roniewicz also considered therizinosaurs to be theropods.[1]

In 1979, Altangerel Perle named the new species Segnosaurus galbinensis, which although he recognized was an unusual theropod, he did not recognize as a therizinosaur. Consequently he named the new family Segnosauridae and, in 1980, Segnosauria.[1] Two years later, Perle recognized commonalities between Therizinosaurus and segnosaurs, reclassifying the former as a member of the latter. From hereout therizinosaur research was considered "segnosaur" research.[3] Perle himself thought that his "segnosaurs" were semi-aquatic fish-eaters. However, in the early 1990s, researchers like Rinchen Barsbold and Maryanska cast doubt on the connection between therizinosaurs and segnosaurs altogether.[3]

Nevertheless, the description Alxasaurus elsitaiensis provided more evidence for a close relationship between the therizinosaurs and "segnosaurs" and led to a revision of their classification. The discovery of this and other primitive therizinosaurs in China formed the beginnings of the third major wave of therizinosaur research.[1] That same year Russell and Russell reinterpreted therizinosaurs as herbivorous foragers like mammalian chalicotherium.[2] Other significant finds of the 1990s include therizinosaur eggs with embryos preserved inside[4] and the first known therizinosaur with feathers, Beipiaosaurus, which was described from China in 1999.[5]

20th century

1950s

1954

1970s

Artist's restoration of Segnosaurus galbinensis

1970

1976

1979

1980s

Skeletal reconstruction of Erlikosaurus andrewsi
Artist's restoration of a male Enigmosaurus mongoliensis courting a female

1980

1981

1982

1983

1984

1986

1989

1990s

Artistic restoration of E. andrewsi with a prosauropod-like body plan
Mounted skeleton of Alxasaurus elesitaiensis
Artistic restoration of Beipiaosaurus inexpectus
Artist's restoration of two Nanshiungosaurus bohlini

1990

1992

1993

1994

1995

1996

1997

1998

1999

21st century

2000s

Eshanosaurus mandible

2000

2001

2002

2005

2007

2010s

2012

2013

See also

Footnotes

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 Clark, Maryanska, and Barsbold (2004); "Systematics and Evolution", page 160.
  2. 1 2 3 4 5 6 7 8 9 Clark, Maryanska, and Barsbold (2004); "Stratigraphy, Paleoecology, and Biogeography", page 163.
  3. 1 2 3 4 5 Clark, Maryanska, and Barsbold (2004); "Systematics and Evolution", page 161.
  4. 1 2 3 4 5 6 Clark, Maryanska, and Barsbold (2004); "Eggs", page 159.
  5. 1 2 3 4 5 6 7 8 Clark, Maryanska, and Barsbold (2004); "Introduction", page 151.
  6. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Clark, Maryanska, and Barsbold (2004); "Table 7.1: Therizinosauroidea", page 152.
  7. Clark, Maryanska, and Barsbold (2004); "Systematics and Evolution", pages 160–161.
  8. Clark, Maryanska, and Barsbold (2004); "Stratigraphy, Paleoecology, and Biogeography", page 164.
  9. Kirkland et al. (2005); "Abstract", page 84.
  10. Li et al. (2007); "Abstract", page 539.
  11. Senter, Kirkland and Deblieux (2012); "Abstract", page 1.
  12. Pu et al. (2013); "Abstract", page 1.

References

This article is issued from Wikipedia - version of the 5/19/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.