Anchors

Anchors
Graphic representation of Anchiornis
Temporal occurrence
Upper Jurassic ( Oxfordium )
163.5 to 157.3 million years
Locations
Tiaojishan Formation ( People's Republic of China )
Systematics
Dinosaur (dinosauria) Lizard dinosaur (Saurischia) Theropoda Deinonychosauria Paraves Anchors
Scientific name
Anchors
Xu et al. , 2009

Anchiornis was a small, bird-like dinosaur from the Paraves group that lived in the early Upper Jurassic ( Oxfordian ). The animal had well-developed feathers on arms and legs and thus four wings, similar to the dromaeosaur Microraptor .

The first description is based on an almost complete fossil that was found in the Tiaojishan Formation in Jianchang in the Chinese province of Liaoning . The fossil is now in the Liaoning Paleontological Museum. There is only one kind of anchiornis huxleyi .

features

Skeletal reconstruction

Fossil with the easily recognizable wings

Size comparison with a modern human based on the largest type specimen found so far

Anchiornis had a triangular skull, seen from the side, with a large front skull window that was only separated from the skull window in front of the eyes by a small bone brace. His teeth weren't sawed.

The postcranial skeleton (skeleton behind the skull) is similar to that of the troodontids . The front legs, however, were longer than those of the troodontids and similar in length to those of the dromaeosaurids and basal birds. Clear fletching can be seen on the well-preserved type specimen. The forearm had ten long flight feathers, the hand had eleven, the lower leg twelve to thirteen, the foot ten to eleven. Hand and arm swings were about the same length. In contrast to the conditions in the "primeval bird" Archeopteryx and Microraptor , the wider part of the wing was proximal (towards the center of the body) in Anchiornis . In addition to the wing feathers on the limbs, Anchiornis had two other types of feathers. Down-like tufted feathers, the filaments of which all converged at the base, and contour feathers, the filaments of which were arranged along a long and firm quill. Despite these properties, the authors of the first description do not believe that Anchiornis was able to fly. The very long lower legs are more an indication of a running lifestyle.

In February 2010, a study was published in the journal Science , in which melanosomes preserved from fossils in the feathers of Anchiornis are reported. Melanosomes give the feathers of today's birds their color. Anchiornis is said to have been of a gray basic color, had a red-brown feather comb like an irokes cut on its head and white contour feathers with black ribbons on the front and rear legs.

Evolution and systematics

The discovery of Anchiornis is especially important because it is a bird-like dinosaur that is older than Archeopteryx . Until then, it was considered problematic that the bird-like dinosaurs were geologically younger than Archeopteryx .

All advanced theropods probably developed very quickly in the early and middle Upper Jurassic . As Anchiornis , the basal dromaeosaur Microraptor and the basal bird Pedopenna show, wing feathers first emerged on the distal (away from the body center) parts of the front legs, hind legs and tail. In the course of further evolution they then migrated to the center of the body. The large wing feathers on the tail and hind legs were initially reduced and then completely lost.

The position of Anchiornis within the bird-like dinosaurs shows the following cladogram :

Paraves	Scansoriopterygidae     † Xiaotingia     † Yixianosaurus     † Pedopenna     † Aurornis     † Sericornus     † Eosinopteryx     † Anchiornis  Eumaniraptora  † Troodontidae     † Dromaeosauridae     Avialae

literature

• Dongyu Hu, Lianhai Hou, Lijun Zhang, Xing Xu : A pre-Archeopteryx troodontid theropod from China with long feathers on the metatarsus. In: Nature . Vol. 461, No. 7264, 2009, pp. 640-643, doi : 10.1038 / nature08322 .

Individual evidence

1. ↑ Dongyu Hu, Lianhai Hou, Lijun Zhang, Xing Xu: A pre-Archeopteryx troodontid theropod from China with long feathers on the metatarsus. In: Nature. Vol. 461, No. 7264, 2009, pp. 640-643, doi : 10.1038 / nature08322 .
2. ↑ Quanguo Li, Ke-Qin Gao, Jakob Vinther, Matthew D. Shawkey, Julia A. Clarke, Liliana D'Alba, Qingjin Meng, Derek EG Briggs , Long Miao, Richard O. Prum: Plumage Color Patterns of an Extinct Dinosaur. In: Science . Vol. 327, No. 5971, 2010, pp. 1369-1372, doi : 10.1126 / science.1186290 .
3. ↑ Ulysse Lefèvre, Andrea Cau, Aude Cincotta, Dongyu Hu, Anusuya Chinsamy, François Escuillié & Pascal Godefroit (2017). A new Jurassic theropod from China documents a transitional step in the macrostructure of feathers. The Science of Nature, 104: 74. doi: 10.1007 / s00114-017-1496-y

Web links

Commons : Anchiornis  - collection of images, videos and audio files