Haplocheirus
| Haplocheirus | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
The holotype of haplocheirus |
||||||||||||
| Temporal occurrence | ||||||||||||
| Upper Jurassic ( Oxfordium ) | ||||||||||||
| 163.5 to 157.3 million years | ||||||||||||
| Locations | ||||||||||||
|
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Haplocheirus | ||||||||||||
| Choiniere , Xu , Clark , Forster , Yu & Han , 2010 | ||||||||||||
Haplocheirus ( Gr .: haplocheir = simple hand) was a small dinosaur from the Upper Jurassic ( Oxfordium ). A very well preserved three-dimensional fossil was found in the Shishugou Formation in the Junggar Basin in Xinjiang (China). Haplocheirus is related to the Alvarezsauridae .
The only type is haplocheirus sollers . The type epithet soller ( Latin : = talented) was given because the forehand was still able to grasp .
features
Haplocheirus was about 1.90 to 2.30 meters long, the exact size is unknown because the end of the tail is missing. Its graceful, low skull is 14 cm long. Of all Alvarezsauriden, of which there are almost complete skeletons , it is the largest genus.
There are 30 teeth on the maxillary , more than on any other Alvarez saurid. The teeth are not conical, as in other Alvarezsauriden, but curved back and slightly serrated. The teeth decrease in size from front to back. This also applies to the teeth on the dentary , which has some large, unsawed teeth in front. Haplocheirus probably still fed on the meat of larger animals, while the later Alvarezsauridae were insect eaters.
In contrast to developed Alvarezsauriden, whose third and fourth fingers of the forehand were greatly reduced and whose enlarged claw of the second finger was converted into a grave claw, Haplocheirus could still grip with his hand. However, the hand of Haplocheirus already shows the later development, the second finger was thickened, the other two thin, the third very much elongated.
Systematics
Haplocheirus is a close relative of the Alvarezsauridae, small, bird-like dinosaurs whose systematic position was previously very uncertain. His find extends the stratigraphic evidence of the group by 63 million years into the past and shows that the Alvarezsauridae were not birds, as was often assumed shortly after their discovery, but that the bird-like features developed several times within the Maniraptora .
The systematic position shows the following cladogram :
| Maniraptora |
|
|||||||||||||||||||||||||||||||||||||||||||||
|
|
literature
- 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 .
Individual evidence
- ^ Gregory S. Paul : The Princeton Field Guide To Dinosaurs. Princeton University Press, Princeton NJ 2010, ISBN 978-0-691-13720-9 , pp. 125–126, Online ( Memento of the original of July 13, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked . Please check the original and archive link according to the instructions and then remove this notice. .
