Post by creature386 on May 3, 2020 23:52:10 GMT 5
Eosinopteryx brevipenna
©El fosilmaníaco
Temporal range: Late Jurassic[1]
Location: Tiaojishan Formation (Liaoning, China)[1]
Scientific classification:
Theropoda
Coelurosauria
Paraves
Anchiornithidae
Eosinopteryx
E. brevipenna[3]
Description:
Eosinopteryx brevipenna was a small theropod from the Oxfordian of China. It is known from a single well-preserved skeleton with fossilized feather impressions. The skeleton belongs to a specimen that was either adult or subadult, as fused sutures show, and reached a total length of about 30 cm. Much like Anchiornis, Eosinopteryx has a triangular skull with large orbitals. Unlike in Anchiornis, however, the snout is much shorter than the orbital in Eosinopteryx.
The teeth are, unlike in many other theropods, not serrated and the tail is comparatively short. The feet and toes are slender and sport short, straight claws. Unlike the curved claws of many related maniraptorans, the claws of Eosinopteryx were most likely neither suited for hunting nor for climbing.
The most distinctive feature of this genus, however, is its integument or rather the lack thereof. The feather integument of Eosinopteryx is significantly thinner than that of other maniraptorans from the Jurassic. Rectrices in the tail region are missing entirely, even though the phylogenetic placement of Eosinopteryx implies that they should be present. This is not the result of poor preservation, as far thinner tail feathers are preserved. It is likely, that Eosinopteryx retrices were secondarily lost in its evolution. Feathers in the foot region are entirely absent.
The longest remiges are 50% longer than the humerus. The combination of short humeri and long feathers likely resulted in a short wingspan and difficulties with flapping. In combination with the reduced tail and leg feathers, this implies that Eosinopteryx was a was a good runner and spent significant time on the ground. This in turn indicates that bird-like non-avian dinosaurs had already diversified into various niches relatively early and did not just use their feathers for flight, but also for insulation or for intimidating conspecifics.
The name "Eosinopteryx" can be freely translated into "Early Chinese Feather". The species name "brevipenna" means "short feather" and refers to the reduced plumage.[1]
Locality:
The holotype of E. brevipenna was discovered in the Tiaojishan Formation which is part of Liaoning, China. The specimen itself is part of the Yizhou Fossil and Geology Park under the catalogue number YFGP-T5197. The researches received it from a Chinese fossil trader. Tests of its authenticity reveal it to have neither been a fraud nor a chimera. The Tiaojishan Formation is difficult to date, owing to its heterogenous composition, which is why estimates for the age of E. brevipenna vary from 165 to 153 ma. The formation causes a variety of well-preserved fossils. Bird-like non-avian dinosaurs like Xiaotingia and Anchiornis had already been discovered in the past.[1]
Phylogenetic position:
The exact phylogenetic placement of Eosinopteryx brevipenna has been the subject of several revisions ever since its discovery. Initially (2013), Eosinopteryx was classified as a sister taxon to Anchiornis and as a basal troodontid. Even there, the researches warned that the classification was not very robust due to the various conversantly evolved traits among the taxa studied.[1]
Later researches (2014) classified Eosinopteryx as a basal avialae and as a sister taxon to Aurornis.[2] A phylogenetic analysis from the year 2017, however, classified Eosinopteryx as a amber of the family Anchiornithidae.[3]
Footnotes:
[1] Godefroit P, Demuynck H, Dyke G, Hu D, Escuillié FO, Claeys P (2013) Reduced plumage and flight ability of a new Jurassic paravian theropod from China. Nature Communications doi:10.1038/ncomms2389
[2] Lefèvre U, Hu D, Escuillié FO, Dyke G, Godefroit P (2014) A new long-tailed basal bird from the Lower Cretaceous of north-eastern China. Biological Journal of the Linnean Society. 113 (3): 790–804. doi:10.1111%2Fbij.12343
[3] Foth C, Rauhut OWM (2017) Re-evaluation of the Haarlem Archaeopteryx and the radiation of maniraptoran theropod dinosaurs. BMC Evolutionary Biology. 17 (1): 236 doi:10.1186%2Fs12862-017-1076-y
©El fosilmaníaco
Temporal range: Late Jurassic[1]
Location: Tiaojishan Formation (Liaoning, China)[1]
Scientific classification:
Theropoda
Coelurosauria
Paraves
Anchiornithidae
Eosinopteryx
E. brevipenna[3]
Description:
Eosinopteryx brevipenna was a small theropod from the Oxfordian of China. It is known from a single well-preserved skeleton with fossilized feather impressions. The skeleton belongs to a specimen that was either adult or subadult, as fused sutures show, and reached a total length of about 30 cm. Much like Anchiornis, Eosinopteryx has a triangular skull with large orbitals. Unlike in Anchiornis, however, the snout is much shorter than the orbital in Eosinopteryx.
The teeth are, unlike in many other theropods, not serrated and the tail is comparatively short. The feet and toes are slender and sport short, straight claws. Unlike the curved claws of many related maniraptorans, the claws of Eosinopteryx were most likely neither suited for hunting nor for climbing.
The most distinctive feature of this genus, however, is its integument or rather the lack thereof. The feather integument of Eosinopteryx is significantly thinner than that of other maniraptorans from the Jurassic. Rectrices in the tail region are missing entirely, even though the phylogenetic placement of Eosinopteryx implies that they should be present. This is not the result of poor preservation, as far thinner tail feathers are preserved. It is likely, that Eosinopteryx retrices were secondarily lost in its evolution. Feathers in the foot region are entirely absent.
The longest remiges are 50% longer than the humerus. The combination of short humeri and long feathers likely resulted in a short wingspan and difficulties with flapping. In combination with the reduced tail and leg feathers, this implies that Eosinopteryx was a was a good runner and spent significant time on the ground. This in turn indicates that bird-like non-avian dinosaurs had already diversified into various niches relatively early and did not just use their feathers for flight, but also for insulation or for intimidating conspecifics.
The name "Eosinopteryx" can be freely translated into "Early Chinese Feather". The species name "brevipenna" means "short feather" and refers to the reduced plumage.[1]
Locality:
The holotype of E. brevipenna was discovered in the Tiaojishan Formation which is part of Liaoning, China. The specimen itself is part of the Yizhou Fossil and Geology Park under the catalogue number YFGP-T5197. The researches received it from a Chinese fossil trader. Tests of its authenticity reveal it to have neither been a fraud nor a chimera. The Tiaojishan Formation is difficult to date, owing to its heterogenous composition, which is why estimates for the age of E. brevipenna vary from 165 to 153 ma. The formation causes a variety of well-preserved fossils. Bird-like non-avian dinosaurs like Xiaotingia and Anchiornis had already been discovered in the past.[1]
Phylogenetic position:
The exact phylogenetic placement of Eosinopteryx brevipenna has been the subject of several revisions ever since its discovery. Initially (2013), Eosinopteryx was classified as a sister taxon to Anchiornis and as a basal troodontid. Even there, the researches warned that the classification was not very robust due to the various conversantly evolved traits among the taxa studied.[1]
Later researches (2014) classified Eosinopteryx as a basal avialae and as a sister taxon to Aurornis.[2] A phylogenetic analysis from the year 2017, however, classified Eosinopteryx as a amber of the family Anchiornithidae.[3]
Footnotes:
[1] Godefroit P, Demuynck H, Dyke G, Hu D, Escuillié FO, Claeys P (2013) Reduced plumage and flight ability of a new Jurassic paravian theropod from China. Nature Communications doi:10.1038/ncomms2389
[2] Lefèvre U, Hu D, Escuillié FO, Dyke G, Godefroit P (2014) A new long-tailed basal bird from the Lower Cretaceous of north-eastern China. Biological Journal of the Linnean Society. 113 (3): 790–804. doi:10.1111%2Fbij.12343
[3] Foth C, Rauhut OWM (2017) Re-evaluation of the Haarlem Archaeopteryx and the radiation of maniraptoran theropod dinosaurs. BMC Evolutionary Biology. 17 (1): 236 doi:10.1186%2Fs12862-017-1076-y