Protopteryx

Protopteryx
Temporal occurrence
	Upper Hauterivium to Lower Barremium
	approx. 131 million years
Locations
	Sichakou Basin , Hebei , China ;
Systematics
	Birds (aves, avialae)
	Enantiornithes
	Protopterygiformes
	Protopterygidae
	Protopteryx
Scientific name
	Protopteryx
	Zhang & Zhou , 2000
Art
	Protopteryx fengningensis;

Protopteryx is a genus of birds in the Jehol Biota. The only known species of the so far monotypical genus is Protopteryx fengningensis from the Huajiying Formation in the Fengning Autonomous Countyin the northeast of the Chinese province of Hebei . He is considered one of the oldest and most primitive representatives of the enantiornithes .

Etymology and history of research

The generic name is made up of the ancient Greek words πρώτος ( protos = "the first", "first") and πτέρυξ ( ptéryx = "wing", "swing", "feather"). The additional species " fengningensis " refers to the place where it was found in the Fengning Autonomous County . According to the first descriptor, the generic name can be translated as "primitive feather".

From protopteryx fengningensis far only two copies are known: The holotype (IVPP V 11665) and a Paratypus (IVPP V 11844). Both specimens show largely complete, articulated skeletons with feather prints and are each in the form of a plate and counterplate. The first description of the genus and type species was carried out in 2000 by Zhang & Zhou .

In 2006, Zhou & Zhang established their own new family ( Protopterygidae ) within their own new order ( Protopterygiformes ) for Protopteryx fengningensis . In the same year, He et al. absolute age data for the fossil-bearing horizon (“ Protopteryx horizon”) based on Ar-Ar dating on potash feldspars from volcanic tufa layers and assigned an age of 130.7 ± 1.4 Ma. This roughly corresponds to the boundary between the uppermost Hauterivium and the lowest Barremium within the Lower Cretaceous .

In the publications mentioned above, the found layer ("Stratum typicum") of Protopteryx fengningensis is given differently, on the one hand the Yixian formation and on the other hand the Dabeigou formation . In 2008, Jin et al. the find horizon within the Huajiying Formation.

features

Protopteryx was roughly the size of a star, whereby the authors of the first description use this size comparison to refer to the white-cheeked star ( Spodiopsar cineraceus = Sturnus cineraceus ), which is very common in East Asia and is slightly larger than the common starling ( Sturnus vulgaris ), which is better known in Europe ).

The most striking feature of Protopteryx are two long central tail feathers . These have a long shaft ( rachis ) that has no feathers made of feather branches at the proximal end . The shaft itself appears flattened like a ribbon. The distal end of the tail feathers is not preserved. Analogous types of feathers ("Proximally Ribbon-like Pennaceous Feathers"; "PRPFs") are also from other basic representatives of the enantiornithes, at least partially also from the genus Confuciusornis, which does not belong to the enantiornithes, and which does not belong to the birds, and from representatives of the Maniraptora known as Epidexipteryx .

The anatomy of Protopteryx generally shows a mixture of primal ("primitive") and more developed ("advanced") features.

As with most representatives of the enantiornithes, teeth are still present, but seem to be greatly reduced in number. Only two pointed, conical, smooth teeth in the area of the premaxilla of the upper jaw and one tooth each in the anterior and middle areas of the lower jaw bone are fossilized.

The hand bones are longer than those of other enanthiornith birds. All three fingers of the hand have strong claws. Thumb wings , important for aerodynamics during slow flight and takeoff, are available. The coracoid already has a small procoracoid. Protopteryx thus has the anatomical prerequisites for a three- bone hole ( foramen triosseum ; "triosseal canal"). In modern birds, a tendon runs through this opening in the shoulder girdle and connects the supracoracoid muscle attached to the sternum with the humerus; a significant adaptation for flight through active wing flapping. Protopteryx could probably fly better than Archeopteryx or Confuciusornis . However, the distal carpal bones and metacarpal bones have not yet completely fused to form the carpometacarpus and are still strongly reminiscent of the anatomical relationships in Archeopteryx .

The synsacrum is made up of seven fused vertebrae. The pygostyle is, like most representatives of the Enantiornithes, with the exception of Cruralispennia , rod-shaped and does not yet show the typical ploughshare shape of the Ornithuromorpha .

The fibula ( fibula ) is similar to Archeopteryx , Confuciusornis and Pengornithidae that with protopteryx not yet greatly reduced most closely related group of basal Enantiornithes but extends almost to the lateral condyle of the Tibiotarsus . Both in modern birds and their closest, extinct relatives (ornithuromorpha), as well as in the more advanced representatives of the enantiornithes, the fibula is, however, greatly shortened and usually only reaches half the length of the tibiotarsus.

Paleecology

For Protopteryx , as for most representatives of the Enantiornithes, a tree-dwelling way of life is assumed.

The rocks of the Huajiying Formation were deposited in the Sichakou sedimentary basin in the northeast of Hebei Province in a lacustrine environment , with volcanic ash and pyroclastics being repeatedly brought into the sedimentation area by a nearby volcanic area .

In addition to Protopteryx , the " Protopteryx horizon" also provided fossils of other early bird representatives such as Eoconfuciusornis , Eopengornis , Cruralispennia and Archaeornithura . Representatives of all three Mesozoic large groups of Pygostylia ( Confuciusornithidae , Enantiornithes and Ornithuromorpha) were already present in this habitat .

There are also two fish from the sturgeon-like order ( Peipiaosteus fengningensis and Yanosteus longidorsalis ), as well as salamanders and mammals. In addition to the remains of vertebrates, there are also fossils of plants and invertebrates (various molluscs , mussel shells , ostracods , but also insects and spiders ). Plant and insect remains are particularly common. The fauna society of the " Protopteryx horizon" is sometimes also referred to as " Peipiaosteus fengningensis - Protopteryx fengningensis Assemblage".

literature

Mee-mann Chang (Ed.): The Jehol Fossils. The Emergence of Feathered Dinosaurs, Beaked Birds and Flowering Plants. Academic Press, Amsterdam et al. 2008, ISBN 978-0-12-374173-8 .
Luis M. Chiappe & Meng Qingjin: Birds of Stone: Chinese Avian Fossils from the Age of Dinosaurs , 304 S., Johns Hopkins University Press, Baltimore, 2016, ISBN 9781421420240 (reading sample)

Individual evidence

^ ^A ^b ^c F. Jin, F. Zhang, Z. Li, J. Zhang, Ch. Li & Z. Zhou: On the horizon of Protopteryx and the early vertebrate fossil assemblages of the Jehol Biota. In: Chinese Science Bulletin Vol. 53, No. 18, pp. 2820–2827, 2008. (digitized version )

↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j F. Zhang & Z. Zhou: A Primitive Enanthiornithine Bird and the Origin of Feathers. In: Science , Vol. 290, pp. 1955–1959, 2000. (digitized version)

^ ^A ^b Z. Zhou & F. Zhang: Mesozoic Birds of China - A Synoptic Review. In: Vertebrata Palasiatica , Vol. 44, pp. 74–98, 2006. (digitized version )
↑ ^a ^b H. Y. He, XL Wang, F. Jin, ZH Zhou, F. Wang, LK Yang, X. Ding, A. Boven & RX Zhu: The ⁴⁰ Ar / ³⁹ Ar dating of the early Jehol Biota from Fengning, Hebei Province, northern China. In: G³ - Geochemistry, Geophysics, Geosystems , Vol. 7, Issue 4, 8 S., 2006. doi : 10.1029 / 2005GC001083
↑ ^a ^b X. Xu. X. Zheng & H. You: Exceptional dinosaur fossils show ontogenetic development of early feathers. In: Nature , Vol. 464, pp. 1338-1341, 2010. doi : 10.1038 / nature08965
↑ ^a ^b ^c M. Wang, JK O'Connor, Y. Pan & Z. Zhou: A bizarre Early Cretaceous enantiornithine bird with unique crural feathers and an ornithuromorph plow-shaped pygostyle. In: Nature Communications , 12 pp., 2017. doi : 10.1038 / ncomms14141
↑ JK O'Connor, LM Chiappe, Ch.-M. Chuong, DJ Bottjer & H. You: Homology and Potential Cellular and Molecular Mechanisms for the Development of Unique Feather Morphologies in Early Birds. In: Geosciences , Vol. 2012, No. 2, pp. 157-177, 2012. doi : 10.3390 / geosciences2030157
^ ^A ^b M. Wang, X. Zheng, JK O'Connor, GT Lloyd, X. Wang, Y. Wang, X. Zhang & Z. Zhou: The oldest record of ornithuromorpha from the early cretaceous of China. In: Nature Communications , 9 pp., 2015. doi : 10.1038 / ncomms7987
↑ F. Zhang, Z. Zhou & MJ Benton: A primitive confuciusornithid bird from China and its implications for early avian flight. In: Science in China Series D: Earth Sciences , Vol. 51, No. 5, pp. 625–639, 2008. (digitized version )

^ X. Wang, JK O'Connor, X. Zheng, M. Wang, H. Hu & Z. Zhou: Insights into the evolution of rachis dominated tail feathers from a new basal enantiornithine (Aves: Ornithothoraces). In: Biological Journal of the Linnean Society , Vol. 113, pp. 805-819, 2014. doi : 10.1111 / bij.12313

[Jin_et_al.,_2008-1] A ^b ^c F. Jin, F. Zhang, Z. Li, J. Zhang, Ch. Li & Z. Zhou: On the horizon of Protopteryx and the early vertebrate fossil assemblages of the Jehol Biota. In: Chinese Science Bulletin Vol. 53, No. 18, pp. 2820–2827, 2008. (digitized version )

[Zhang_&_Zhou,_2000-2] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j F. Zhang & Z. Zhou: A Primitive Enanthiornithine Bird and the Origin of Feathers. In: Science , Vol. 290, pp. 1955–1959, 2000. (digitized version)