Eosinopteryx
| Eosinopteryx | ||||||||||||
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Live reconstruction of Eosinopteryx brevipenna |
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| Temporal occurrence | ||||||||||||
| Upper Jurassic ( Oxfordian to Kimmeridgian ) | ||||||||||||
| 165 to 153 million years | ||||||||||||
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| Scientific name | ||||||||||||
| Eosinopteryx | ||||||||||||
| Godefroit , Demuynck , Dyke , Hu , Escuillié & Claeys , 2013 | ||||||||||||
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Eosinopteryx was a genus of theropod dinosaur from the Oxfordium of China . The genus represents one of many mosaic forms between birds and dinosaurs. It is very similar to Anchiornis , but probably had a weaker plumage and less pronounced ability to fly than comparable taxa.
description
Eosinopteryx is known for a single well-preserved skeleton with fossilized feather prints . It comes from a specimen that was either adult or subadult during its lifetime, as the closed bone sutures show, and which reached a body length of approximately 30 cm. Similar to Anchiornis , Eosinopteryx has a triangular skull with a large eye socket when viewed from the side . In contrast to Anchiornis , the snout is significantly shorter than the eye socket.
Unlike many other theropods, the teeth are not serrated and the tail is comparatively short. The feet and toes are slender and have short, straight claws that, unlike the curved claws of many related maniraptors, may have been less suitable for hunting or climbing.
However, what sets this genus apart from other bird-like dinosaurs is the feathering. The plumage of Eosinopteryx is thinner than that of other Maniraptora from the Jurassic period . Feathers (Engl. Retrices) are missing, for example, entirely by the tail, although the relationships of Eosinopteryx indicate that they should be present. This is not due to poor preservation, as prints of much more fragile feathers have been preserved all over the tail. It is believed that Eosinopteryx regressed its control feathers secondarily. Feathers are completely absent in the foot region.
The longest hand wings are about 50% longer than the humerus . This combination of short humerus bones and long feathers presumably resulted in a relatively small wing span and difficulties in flapping the wings. This, combined with the reduced leg and tail feathers, suggests that Eosinopteryx was a good runner who spent a lot of time on the ground. This in turn shows that bird-like dinosaurs occupied various niches early on and developed their feathers not only for flying, but also for insulating or impressing fellows.
The name "Eosinopteryx" can be freely translated as "early Chinese feather". The species name "brevipenna" means "short feather" and refers to the greatly reduced plumage.
Location
The holotype of E. brevipenna was found in the Daohugou strata , which are located in Liaoning ( China ). The specimen is part of the Yizhou Fossil and Geology Park under catalog number YFGP-T5197. The researchers obtained it from a Chinese fossil dealer and research has shown that it is neither a fake nor a chimera . The Daohugou strata are difficult to date due to their heterogeneous composition, which is why calculations for the age of E. brevipenna range from 165 to 153 million years . The formation has a variety of well-preserved fossils. Other bird-like dinosaurs such as Xiaotingia and Anchiornis had been discovered in it in the past .
Systematics
The exact classification of Eosinopteryx brevipenna in the theropod family tree has been revised several times since its discovery. Originally (2013) Eosinopteryx was classified as the sister taxon of Anchiornis and as a basal troodontid . At that point in time, however, the researchers warned that the classification was not very robust in the animals examined because of the numerous convergent characteristics .
Later researchers (2014) classified Eosinopteryx as basal paraves and sister taxons of Aurornis . A phylogenetic analysis from 2017 classifies Eosinopteryx as a member of the Anchiornithidae family .
Individual evidence
- ↑ a b c d P. Godefroit, H. Demuynck, G. Dyke, D. Hu, FO Escuillié, P. Claeys: Reduced plumage and flight ability of a new Jurassic paravian theropod from China . In: Nature Communications . 4, 2013, p. 1394. bibcode : 2013NatCo ... 4E1394G . doi : 10.1038 / ncomms2389 . PMID 23340434 .
- ↑ U. Lefèvre, D. Hu, FO Escuillié, G. Dyke, P. Godefroit: A new long-tailed basal bird from the Lower Cretaceous of north-eastern China . In: Biological Journal of the Linnean Society . 113, No. 3, 2014, pp. 790-804. doi : 10.1111 / bij.12343 .
- ^ C. Foth, OWM Rauhut: Re-evaluation of the Haarlem Archeopteryx and the radiation of maniraptoran theropod dinosaurs . In: BMC Evolutionary Biology . 17, No. 1, 2017, p. 236. doi : 10.1186 / s12862-017-1076-y . PMID 29197327 . PMC 5712154 (free full text).