Alvarezsauridae

Alvarezsauridae
Graphic reconstruction of the skeleton and outline of Linhenykus monodactylus
Temporal occurrence
Oxfordium ( Upper Jurassic ) to Maastrichtium ( Upper Cretaceous )
163.5 to 66 million years
Locations
Asia North America South America
Systematics
Lizard dinosaur (Saurischia) Theropoda Coelurosauria Maniraptora Alvarezsauroidea Alvarezsauridae
Scientific name
Alvarezsauridae
Bonaparte , 1991

The Alvarezsauridae are a family group ( taxon ) of bird-like theropod dinosaurs within the Coelurosauria . They lived from the Upper Jurassic to the Upper Cretaceous in Asia , North and South America , and they may also have occurred in Australia and Europe .

features

The Alvarezsauriden were slender and long-legged animals that were half a meter to two meters long. The front legs were very short but strong. One finger, the thumb , is greatly enlarged and has a sharp claw, the other two fingers are reduced to tiny remains. It is believed, among other things, that the front legs were used to dig for state-forming insects such as termites . The Alvarezsauridae share a number of characteristics with birds. Her small breastbone (sternum) is provided with a sternum ridge that enlarges the attachment surface for the muscles of the front limbs. As in birds, the carpal and metacarpal bones are fused together ( Carpometacarpus ). In shuvuuia were spring-like structures found.

Systematics

Smaller Alvarezsauridae (Parvicursorinae) in size comparison ( from left to right ):
Parvicursor remotus
Ceratonykus oculatus
Shuvuuia deserti
Mononykus olecranus

The Alvarezsauridae were originally assigned very close to the birds , for example as a sister group of Archeopteryx . However, this notion was relativized by later discovered but more primitive forms such as Haplocheirus , Patagonykus and Alvarezsaurus , which do not show all the bird-like features of the first discovered genera Mononykus and Shuvuuia . The corresponding characteristics could therefore also have developed independently ( convergently ) in birds and the late Alvarezsauriden .

The systematic position of the Alvarezsauridae is still controversial and the subject of controversial debates. They are placed within the Coelurosauria to the Maniraptora or as a sister group of the Ornithomimosauria to the Ornithomimiformes .

• Alvarezsauroidea
  • Haplocheirus
• Alvarezsauridae
  • Alvarezsaurus
  • Heptasteornis ?
  • Kol ?
  • Patagonykinae
    • Achillesaurus ?
    • Bonapartenykus
    • Patagonykus
  • Parvicursorinae
    • "Ornithomimus" minutus
    • Parvicursor
    • Ceratonykini
      • Albinykus
      • Ceratonykus
      • Xixianykus
    • Mononykini
      • Albertonykus
      • Linhenykus
      • Mononykus
      • Shuvuuia

literature

Live reconstruction of Linhenykus

• David E. Fastovsky , David B. Weishampel : The Evolution and Extinction of the Dinosaurs. 2nd Edition. Cambridge University Press, Cambridge 2005, ISBN 0-521-81172-4 .

Individual evidence

1. ^ ^{A b} Jonah N. Choiniere, Xing Xu, James M. Clark , Catherine A. Forster, Yu Guo, Fenglu Han: A basal alvarezsauroid theropod from the Early Late Jurassic of Xinjiang, China. In: Science . Vol. 327, No. 5965, 2010, pp. 571-574, doi : 10.1126 / science.1182143 .
2. ^ ^{A b} Thomas R. Holtz Jr .: Dinosaurs. Random House, New York NY 2007, ISBN 978-0-375-82419-7 , pp. 136-138.
3. ^ Alan H. Turner, Sterling J. Nesbitt, Mark A. Norell : A Large Alvarezsaurid from the Late Cretaceous of Mongolia (= American Museum Novitates. No. 3548). American Museum of Natural History, New York NY 2009, digital copy (PDF; 2.97 MB) .

Web links

Commons : Alvarezsauridae  - Collection of images, videos and audio files

• Alvarezsauridae in Mikko's Phylogeny Archive (English)