Longipteryx

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Longipteryx
Fossil range: Early Cretaceous (Barremian?)
Reconstruction (plumage color is conjectural; tail length and shape is unknown)
Reconstruction (plumage color is conjectural; tail length and shape is unknown)
Conservation status
Fossil
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Subclass: Enantiornithes?
Superorder: Euenantiornithes?
Order: Longipterygiformes (disputed)
Zhang, Zhou, Hou & Gu, 2001
Family: Longipterygidae (disputed)
Zhang, Zhou, Hou & Gu, 2001
Genus: Longipteryx
Zhang, Zhou, Hou & Gu, 2001
Species: L. chaoyangensis
Binomial name
Longipteryx chaoyangensis
Zhang, Zhou, Hou & Gu, 2001
This specimen, unlike the holotype, lacks well-preserved feathers
This specimen, unlike the holotype, lacks well-preserved feathers

Longipteryx is a genus of prehistoric bird which lived during the Early Cretaceous, perhaps in the Barremian (130-125 million years ago). It contains a single species, Longipteryx chaoyangensis[1]. Its remains have been recovered from the Jiufotang Formation at Chaoyang in Liaoning Province, PRC. Apart from the holotype IVPP V 12325 - a fine and nearly complete skeleton -, another entire skeleton (IPPV V 12552) and some isolated bones[2] are known to date.[3]

Excluding the tail, it was some 15 cm long overall in life. It had a long bill - longer than the rest of the head - with a few hooked teeth at the tip, and, as the name implies, proportionally long and strong wings. Although it was primitive insofar as that it had 2 long separate fingers with claws and a stubby thumb, the flight apparatus was generally quite well-developed, and unlike most other birds of its time it possessed uncinate processes which strengthen the ribcage. Its claws and toes were long and strong while the leg was quite short. Altogether, the ability to fly and to perch was quite sophisticated for its age, to the detriment of terrestrial locomotion: the humerus was 1.56 times the length of the femur.[4]

The holotype retains many feather impressions. These are a bit puzzling, as remiges do not seem to have been preserved and what feathers remain are apparently only body feathers, wing coverts and down[3]. The well-developed flight apparatus appears to preclude the possibility that Longipteryx was flightless; perhaps the specimen was moulting when it died, with those remiges that were not already shed in life detaching from the dead bird. On the other hand, a similar way of fossilization is found in some specimens of Confuciusornis which is known to have had very long remiges. Unfortunately, the end of the tail is destroyed in the holotype; no rectrices are preserved and while the pygostyle seems complete in the other skeleton, few remains of feathers occur in that specimen[3]. It is interesting to note however that rectrices like those in Neognathae have not (yet) been found in Enantiornithes and other early birds[5].

It probably dived or probed for fish, crustaceans, or other aquatic animals of appropriate size. Altogether, it was perhaps closest to a modern-day kingfisher in its ecological niche[3]; however, in reality its habits as well as the ecosystem it lived in must have been well distinct enough for there being no actually close living equivalent.

Its affiliations are not resolved. While it has been sometimes included in the Enantiornithes[6] and groups specifically with Euenantiornithes in some cladistic analyses[7], it might be basal to or in Enantiornithes, being somewhat reminiscent of the equally puzzling Protopteryx[8]. Its plesiomorphies are comprehensive, as can be expected from its old age, but the autapomorphies appear quite "modern", especially compared to other early Enantiornithes.[3]

A distinct order (Longipterygiformes) and family (Longipterygidae) has been proposed for it[3], but this move is often regarded as premature. Given that neither its exact relationships nor any close relatives are presently known, not much can be said about the phylogenetic position of L. chaoyangensis. On the other hand, Longirostravis hani, described a few years after Longipteryx, appears to be phylogenetically closer to the present taxon than other Mesozoic birds and indeed they might constitute a clade of early specialized Euenantiornithes[9]. If this is correct, they might well be considered as an order, in which case Longirostravisiformes and Longirostravisidae would become junior synonyms of Longipterygiformes and Longipterygidae, respectively.

[edit] Footnotes

  1. ^ Etymology: Longipteryx, "one with long remiges", from Latin longus, "long" + Ancient Greek pteryx (πτέρυξ), "wing", "feather" or "pinion". chaoyangensis, Latin for "from Chaoyang".
  2. ^ Humerus and furcula (IPPV V 12553) and an ulna (IPPV V 12554)
  3. ^ a b c d e f Zhang et al. (2001)
  4. ^ Zhang et al. (2001), Lamanna et al. (2006)
  5. ^ Clarke et al. (2006)
  6. ^ E.g. Zhang et al. (2001), Gong et al. (2004)
  7. ^ E.g. Mortimer (2004a)
  8. ^ Mortimer (2004b)
  9. ^ Mortimer (2004a)

[edit] References

  • Clarke, Julia A.; Zhou, Zhonghe & Zhang, Fucheng (2006): Insight into the evolution of avian flight from a new clade of Early Cretaceous ornithurines from China and the morphology of Yixianornis grabaui. Journal of Anatomy 208 (3):287-308. doi:10.1111/j.1469-7580.2006.00534.x PDF fulltext Electronic Appendix
  • Gong, Enpu; Hou, Lianhai & Wang, Lixia (2004) Enantiornithine Bird with Diapsidian Skull and Its Dental Development in the Early Cretaceous in Liaoning, China. Acta Geologica Sinica 78(1): 1-7. PDF fulltext
  • Lamanna, Matthew C.; You, Hailu; Harris, Jerald D.; Chiappe, Luis M.; Ji, Shuan; Lü, Junchang & Ji, Qiang (2006): A partial skeleton of an enantiornithine bird from the Early Cretaceous of northwestern China. Acta Palaeontologica Polonica 51(3): 423–434. PDF fulltext
  • Mortimer, Michael (2004a): The Theropod Database: Phylogeny of taxa. Retrieved 2007-OCT-29.
  • Mortimer, Michael (2004b): Tyrannosauroids and dromaeosaurs. Analysis posted on Dinosaur Mailing List 2004-FEB-21. Retrieved 2007-OCT-29.
  • Zhang, Fucheng; Zhou, Zhonghe; Hou, Lianhai & Gu, Gang (2001): Early diversification of birds: Evidence from a new opposite bird. Chinese Science Bulletin 46(11): 945-949. PDF fulltext

[edit] External links


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