Haopterus

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Haopterus
Haopterus gracilis (Holotype IVPP V11726)

Haopterus gracilis (Holotype IVPP V11726)

Temporal occurrence
Lower Cretaceous ( Barremium to Lower Aptium )
~ 130 to ~ 122 million years
Locations
Systematics
Archosauria
Ornithodira
Flugsaurier (Pterosauria)
Short-tailed pterosaur (Pterodactyloidea)
Ornithocheiroidea
Haopterus
Scientific name
Haopterus
Wang & Lü , 2001
Art
  • Haopterus gracilis

Haopterus is a genus of short-tailed pterosaurs from the group of Ornithocheiroidea . The only known species of the so far monotypical genus is Haopterus gracilis from the Yixian formation ( Jehol group ) of Liaoning in northeast China .

Etymology and history of research

The generic name honors the Chinese paleontologist Hao Yichun for her contributions to the research of the Jehol biota in combination with the ending " -pterus ", which is often used by representatives of the pterosaurs , latinized from the ancient Greek πτερόν ( pterón ) "wing". The additional species “ gracilis ” ( Latin : “slim”, “thin”, “fine”) refers to both the excellent state of preservation of the holotype and its tiny metatarsals .

The holotype and so far the only fossil record of Haopterus gracilis was found during the 1998 excavation season near Sihetun in the Shangyuan community near Beipiao in the west of Liaoning Province in the deeper Yixian Formation. The first description of the genus and type species was carried out in 2001 by Wang Xiaolin and Lu Junchang . The original fossil is kept at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences (IVPP) under inventory number IVPP V11726.

At the time of the first description, Haopterus was the first known remnant of a pterosaur with a largely intact skull for the Jehol group.

Fossil evidence and age rating

IVPP V11726 comprises a well-preserved partial skeleton with a largely complete skull including the lower jaw, cervical and dorsal vertebrae, the shoulder girdle and both front limbs, as well as the sternum and individual rib fragments and gastralia . The cross and tail vertebrae are not preserved. There is only a small fragment of the left ischium of the pelvic girdle , and apart from the tarsus , metatarsal and some toe bones, most of the skeletal elements of the hind limbs are missing.

The epiphyses of the preserved long bones are comparatively little ossified and the fossil is interpreted as the remains of a subadult specimen.

The find comes from the fossil-rich Jianshangou member of the Yixian formation as part of the Jehol group . The age of the Yixian formation could be limited in time with the help of the 39 Ar- 40 Ar method . A basaltic lava flow at the base of the formation has a radiometric age of 129.7 ± 0.5  Ma . The minimum age of the formation is given by dating a tufa layer in the most lying parts of the overlying Jiufotang formation with 122.1 ± 0.3 Ma. The period between these two boundary marks corresponds to the Barremium to the Lower Aptium of the Lower Cretaceous .

features

(The description is based on the initial description.)

With a wingspan of 1.35 meters, Haopterus gracilis is a rather small to medium-sized representative of the pterosaurs.

The skull is relatively large with a length of 14.5 cm, elongated and with a pointed rostrum . There are no sagittal crests on the skull. The nasoantorbital window, a cranial window that consists of the fusion of the outer nostril and the antorbital window , is elongated and elliptical and takes up a little more than a quarter of the total length of the skull. Both the upper and lower jaws are equipped with twelve posteriorly curved, pointed teeth up to about the middle of the nasoantorbital window .

The front extremities are very robust. The humerus bones are short, straight and strong. The " crista deltopectoralis " ("deltopectoral crest"), a bone ridge on the humerus, which serves as a muscle attachment and is particularly strong in pterosaurs, is extensive and semicircular. The metacarpal bone of the flying finger is a good third longer than the humerus and the individual phalanxes of the flying finger are also each longer than the corresponding metacarpal bone.

The metatarsals are slender and small. The sternum , on the other hand, is large, fan-shaped, as long as it is wide, and has a clearly developed keel.

Systematics

Haopterus gracilis was originally interpreted as a representative of the Pterodactylidae by the first descriptors. The find would not only have been the first evidence of this controversial family in Asia, but also their youngest representative. Immediately after the first description was published, however, this assignment was called into question again and David Unwin placed Haopterus in the group of the ornithocheiroidea.

In a much noticed and often cited analysis of the phylogenesis and evolutionary history of the pterosaurs, Unwin specified his first assessment of Haopterus in 2003 and evaluates him as a representative of the Ornithocheiridae within the Ornithocheiroidea. In fact, in this work he defines the taxon of the Ornithocheiridae as “the youngest common ancestor of Haopterus gracilis and Ornithocheirus simus and all of its descendants.” However, later phylogenetic analyzes identified Haopterus gracilis as a “rogue taxon”, i.e. the taxon that was analyzed no stable systematic position could be assigned, alternately within the Pterodactyloidea , the Ornithocheiroidea, the Pteranodontoidea , the Istiodactylidae or as sister taxon of the Ornithocheiroidea. Two analyzes published independently in 2019 found Haopterus to be consistent within the group of Ornithocheiroidea, but differing once as a sister taxon to a common clade from Hongshanopterus + Istiodactylidae and in the other case as more closely related to the Annexueridae than to the Istiodactylidae.

Accordingly, Haopterus is rated here as a representative of the ornithocheiroidea. The inner systematics of the short-tailed pterosaurs is still strongly in flux and the systematic position of Haopterus has by no means been conclusively clarified.

Paleecology

The slender, sharp teeth in the front jaw area are taken as an indication of a piscivorous diet of Haopterus . The well-developed shoulder girdle and the equally strong front limbs indicate a good flier. The filigree metatarsal bones, on the other hand, allow the conclusion that Haopterus moved quadruped on the ground or assumed a resting position hanging on the hind legs.

The volcanic sedimentary sequence of the Yixian Formation was deposited in the area of ​​a rift valley ("Fuxin-Yixian Basin"). The sedimentary basin was far back haopterus characterized by extended, very deep in some freshwater lakes and the impact of frequent volcanic eruptions. The particularly fossil-rich Jianshangou member from the area around Sihetun represents the deposits of such a lake ("Lake Sihetun"), interspersed with numerous layers of volcanic ash . "Lake Sihetun" was at least temporarily a meromictic body of water and the lack of oxygen at the bottom of the lake favored the formation of fossils. Not only were the inhabitants of the lake preserved, but also remnants of fauna and flora from the adjacent land areas.

The area around the lake was probably densely forested. Conifers , pteridophytes and representatives of the Bennettitales and Ginkgoales dominate the fossil plant remains of the Jianshangou member . Early, herbaceous representatives of the Bedecktsamer , such as Archaefructus or Hyrcantha , on the other hand, were probably restricted to shallow water areas near the banks . The paleobotanical findings can be interpreted as mesophytic to semi- xerophytic forests in a humid to partially sub-humid, subtropical climate.

Haopterus shared this habitat, among others, with at least two other genera of pterosaurs ( Dendrorhynchoides and Jeholopterus ), the early bird Confuciusornis and Liaoningornis , the feathered dinosaurs Sinosauropteryx , Caudipteryx , PROTARCHAEOPTERYX , Sinornithosaurus and Huaxiagnathus and mammals Jeholodens , Zhangheotherium and repenomamus .

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 .

Individual evidence

  1. ↑ a b c d e f g h i j X. Wang & J. Lü: Discovery of a pterodactylid pterosaur from the Yixian Formation of western Liaoning, China. In: Chinese Science Bulletin , Volume 46, Number 13, 2001, pp. 1112-1117, ( digitized ).
  2. ^ X. Wang & Z. Zhou: Pterosaurs. In: M. 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 , pp. 99-108 ( reading sample ).
  3. ↑ a b Y. Wang, PE Olsen, J. Sha, X. Yao, H. Liao, Y. Pan, S. Kinney, X. Zhang and X. Rao: Stratigraphy, correlation, depositional environments, and cyclicity of the Early Cretaceous Yixian and? Jurassic-Cretaceous Tuchengzi formations in the Sihetun area (NE China) based on three continuous cores. In: Palaeogeography, Palaeoclimatology, Palaeoecology , Volume 464, 2016, pp. 110-133, ( digitized version ).
  4. ^ S. Chang, H. Zhang, PR Renne & Y. Fang: High-precision 40 Ar / 39 Ar age for the Jehol Biota. In: Palaeogeography, Palaeoclimatology, Palaeoecology , Volume 280, Numbers 1-2, 2009, pp. 94-104, ( abstract ).
  5. ^ DM Unwin: An overview of the pterosaur assemblage from the Cambridge Greensand (Cretaceous) of Eastern England. In: Mitteilungen Museum für Naturkunde Berlin, Geoscientific Series , Volume 4, 2001, pp. 189–221, ( digitized version ).
  6. ↑ DM Unwin: On the phylogeny and evolutionary history of pterosaurs. In: E. Buffetaut & J.-M. Mazin (Ed.): Evolution and Palaeobiology of Pterosaurs , Geological Society of London - Special Publications, Number 217, 2003, pp. 139-190, ( digitized ).
  7. ↑ B. Andres & TS Myers: Lone Star Pterosaurs. In: Earth and Environmental Science Transactions of the Royal Society of Edinburgh , Volume 103, 2013, pp. 383-398, ( digitized ).
  8. ↑ X. Zhou, RV Pêgas, MEC Leal & N. Bonde: Nurhachius luei, a new istiodactylid pterosaur (Pterosauria, Pterodactyloidea) from the Early Cretaceous Jiufotang Formation of Chaoyang City, Liaoning Province (China) and comments on the Istiodactylidae. In: PeerJ , 7: e7688, 2019, doi : 10.7717 / peerj.7688 .
  9. ↑ B. Holgado, RV Pêgas, JI Canudo, J. Fortuny, T. Rodrigues, J. Company & AWA Kellner: On a new crested pterodactyloid from the early Cretaceous of the Iberian peninsula and the radiation of the clade Appendixueria. In: nature: Scientific Reports , Volume 9, Article Number 4940, 2019, 10 pp., Doi : 10.1038 / s41598-019-41280-4 .
  10. ^ W. Lin & Q. Wang: Late Mesozoic extensional tectonics in the North China block: a crustal response to subcontinental mantle removal ?. In: Bulletin de la Societe Geologique de France , Volume 177, Number 6, 2006, pp. 287-297, ( digitized ).
  11. ↑ M. Hethke, FT Fürsich, B. Jiang & R. Klaus: Oxygen deficiency in Lake Sihetun; formation of the Lower Cretaceous Liaoning fossil site (China). In: Journal of the Geological Society , Volume 170, 2013, pp. 817-831, ( digitized ).
  12. ^ A b S. Guo, J. Sha, L. Bian & Y. Qiu: Male spike strobiles with Gnetum affinity from the Early Cretaceous in western Liaoning, Northeast China. In: Journal of Systematics and Evolution , Volume 47, Number 2, 2009, pp. 93-102, doi : 10.1111 / j.1759-6831.2009.00007.x .
  13. ^ Q. Ji, H. Li, LM Bowe, Y. Liu & DW Taylor: Early Cretaceous Archaefructus eoflora sp. nov. with Bisexual Flowers from Beipiao, Western Liaoning, China. In: Acta Geologica Sinica , Volume 78, Number 4, 2004, pp. 883-896, ( digitized version ).
  14. ^ DL Dilcher, G. Sun, Q. Ji & H. Li: An early infructescence Hyrcantha decussata (comb. Nov.) From the Yixian Formation in northeastern China. In: PNAS , Volume 104, Number 22, 2007, pp. 9370-9374, ( digitized version ).
  15. ↑ P. Chen, Q. Wang, H. Zhang, M. Cao, W. Li, S. Wu & Y. Shen: Jianshangou Bed of the Yixian Formation in West Liaoning, China. In: Science in China Series D Earth Sciences , Volume 48, Number 3, 2005, pp. 298-312, ( digitized ).

Web links

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