''Gobipteryx'' (from Gobi eferring to the Gobi Desert where it was first discovered and Greek pteryx “wing”) is a genus of prehistoric bird from the Campanian Age of the Late Cretaceous Period.Elżanowski, A. (1974): Preliminary note on the Palaeognthous bird from the Upper Cretaceous of Mongolia ''Palaeontologia Polonica'' 30. It is not known to have any direct descendants. Like the rest of the

enantiornithes The Enantiornithes, also known as enantiornithines or enantiornitheans in literature, are a group of extinct avialans ("birds" in the broad sense), the most abundant and diverse group known from the Mesozoic era. Almost all retained teeth and cla ...

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

, ''Gobipteryx'' is thought to have gone extinct near the end of the Cretaceous.Padian, K. (2004). "Basal Avialae". chptr 11, in Weishampel, D.B., Dodson, P. and Osmólska, H. (eds.): ''The Dinosauria'' 2nd Edition. University of California Press, Berkeley .

Description

Based on a skull length of 45 millimeters, ''Gobipteryx'' has been estimated to be approximately the size of a partridge.Elżanowski, A. (1976): Palaeognathous bird from the Cretaceous of Central Asia '' Nature'' 264: 51-53. Its bones are fibrolamellar.Chinsamy, A., Elżanowski, A. (2001): Bone histology: Evolution of growth pattern in birds ''Nature'' 412.

Skull

The skull's general shape is gradually tapering toward the front. ''Gobipteryx'' has a toothless beak formed from the fusion of the premaxillae bones.Chatterjee, S. (1997): ''The Rise of Birds: 225 Million Years of Evolution'' The Johns Hopkins University Press . The skull is characterized as being

rhynchokinetic Cranial kinesis is the term for significant movement of skull bones relative to each other in addition to movement at the joint between the upper and lower jaw. It is usually taken to mean relative movement between the upper jaw and the braincase. ...

with the pterygoid bones articulating with both the vomersElżanowski, A. (1977): Skulls of ''Gobipteryx'' (Aves) from the Upper Cretaceous of Mongolia ''Palaeontologia Polonica'' 37 p. 153-166. and the palatine. The nares are tear shaped and the choana is located below them, more rosteral than in most modern birds.Chiappe, Luis M.; Norell, Mark and Clark, James (2001): A New Skull of ''Gobipteryx minuta'' (Aves: Enantiornithes) from the Cretaceous of the Gobi Desert. ''American Museum Novitates'' 3346: 1–15

/ref> The nares are smaller than the antorbital fenestrae, a basal feature for

ornithurae Ornithurae (meaning "bird tails" in Greek) is a natural group which includes the common ancestor of ''Ichthyornis'', ''Hesperornis'', and all modern birds as well as all other descendants of that common ancestor. Classification Ernst Haeckel coi ...

birds. In addition, ''Gobipteryx's'' skull has an articulated rostrum. The jaw hinge is associated with the articulation of the

quadrate Quadrate may refer to: * Quadrate bone * Quadrate (heraldry) * Quadrate lobe of liver * Quadrate tubercle The quadrate tubercle is a small tubercle found upon the upper part of the femur. It serves as a point of insertion of the quadratus femori ...

with the pterygoid

processes A process is a series or set of activities that interact to produce a result; it may occur once-only or be recurrent or periodic. Things called a process include: Business and management *Business process, activities that produce a specific se ...

. The articular region of the mandible contains internal and retroarticular processes and has uniform symphysis. This animal has a large, uniform, and sutureless

braincase In human anatomy, the neurocranium, also known as the braincase, brainpan, or brain-pan is the upper and back part of the skull, which forms a protective case around the brain. In the human skull, the neurocranium includes the calvaria or skul ...

Vertebral Column

The vertebral column consists of at least 19 presacral vertebrae, the last six of these being dorsals.Elżanowski, A. (1981): Embryonic Bird Skeletons from the Late Cretaceous of Mongolia. Palaeontologica Polonica 42, 147-179. The neural spines of the twelfth and thirteenth vertebrae form the nuchal blade, which represents the point of greatest elevation in the vertebral column.

Shoulder Girdle

The scapula contains a prominent

glenoid labrum The glenoid labrum (glenoid ligament) is a fibrocartilaginous structure (not a fibrocartilage as previously thought) rim attached around the margin of the glenoid cavity in the shoulder blade. The shoulder joint is considered a ball and socket ...

and tapers backward, ending as thin rods. The

coracoids A coracoid (from Greek κόραξ, ''koraks'', raven) is a paired bone which is part of the shoulder assembly in all vertebrates except therian mammals (marsupials and placentals). In therian mammals (including humans), a coracoid process is prese ...

are slightly concave anteriorly and are separate from the scapulae dorsally. They also stick out from the neck on either side. ''Gobipteryx's'' clavicles curve in a way that is consistent with that of other birds.

Limbs

The

humerus The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a roun ...

is posteriorly convex (a normal trait for birds) and the head is comma-shaped. ''Gobipteryx's'' ulna is about twice as thick as the radius. Metacarpals II and III have been found in embryonic fossils and are observed to be about equal size and are in close contact with each other.

Paleobiology

Flight

''Gobipteryx'' is believed to have been capable of flight. The scapula is long, and therefore, well suited for flight by having more area for muscle attachment. In addition, the

forelimb A forelimb or front limb is one of the paired articulated appendages (limbs) attached on the cranial ( anterior) end of a terrestrial tetrapod vertebrate's torso. With reference to quadrupeds, the term foreleg or front leg is often used instead. ...

of ''Gobipteryx'' is more than twice the length of the thorax, falling within the acceptable range observed in flying birds.

Development

''Gobipteryx'', along with other enantiornithes, is thought to have superprecocial development, in which it was capable of flying upon hatching. Evidence for this comes from the fact that the forelimbs and shoulders of advanced embryos are almost completely ossified. In addition, the growth of ''G. minuta'' has been shown to slow down immediately following hatching. This suggests that it was highly mobile in its life, since locomotion has been shown to slow the growth of young birds by focusing energy and resources elsewhere. This onset of flight so early in life is not seen in most modern birds, which begin flying when they have reached or are close to full size.

History

The first specimens were two damaged skulls discovered as part of the 1971 Polish-Mongolian Paleontological Expedition to the

Gobi Desert The Gobi Desert (Chinese: 戈壁 (沙漠), Mongolian: Говь (ᠭᠣᠪᠢ)) () is a large desert or brushland region in East Asia, and is the sixth largest desert in the world. Geography The Gobi measures from southwest to northeast an ...

by Dr. Teresa Maryańska, however, at the time, it was not immediately recognized that both of these skulls belonged to ''Gobipteryx''. It was first found in the sandstones of the Lower Nemegt Beds of the Barun Goyot Formation of the Nemegt Basin. The holotype specimen is housed at the Institute of Paleobiology of the Polish Academy of Sciences in Warsaw, Poland and was first described by Dr. Andrzej Elżanowski using a single damaged skull. Initially, ''Gobipteryx'' was classified as a member of the clade

Palaeognathae Palaeognathae (; ) is a infraclass of birds, called paleognaths, within the class Aves of the clade Archosauria. It is one of the two extant infraclasses of birds, the other being Neognathae, both of which form Neornithes. Palaeognathae contai ...

on the basis of its jaw and palate. However, in 1981, Dr. Cyril Walker defined the clade enantiornithesWalker, C. A. (1981): New subclass of birds from the Cretaceous of South America ''Nature'' 292 p. 51-53. and ''Gobipteryx'' was reclassified as an enantiornithes bird. In 1996, Evgeny Kurochkin described a new bird known as ''Nanantius valifanovi'' also from the Barun Goyot Formation.Kurochkin, E. (1996): A new enantiornithid of the Mongolian Late Cretaceous, and the general appraisal of the Infraclass Enantiornithes (Aves). ''Russian Academy of Sciences, Palaeontological Institute, Special Issue'': 1-50. However, it was later discovered that ''N. valifanoi'' was actually a new misidentified specimen of ''Gobipteryx minuta''. The mistake was, at least in part, due to a misidentification of the maxilla and dentary bones of the skull. In 1994, an expedition to the Gobi Desert was conducted by the

American Museum of Natural History The American Museum of Natural History (abbreviated as AMNH) is a natural history museum on the Upper West Side of Manhattan in New York City. In Theodore Roosevelt Park, across the street from Central Park, the museum complex comprises 26 inter ...

and the Mongolian Academy of Sciences, where a well preserved ''Gobiptetyx minuta'' skull was found in the Nemegt Basin. This new specimen provided further evidence for the placement of ''Gobipteryx'' into enantiornithes. In addition, it allowed for the reconstruction of the palate, which was poorly understood in Mesozoic birds. Also during the 1971 Polish-Mongolian Paleontological Expedition to the Gobi Desert, in which the first specimens were found, advanced

embryo An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male spe ...

s of ''Gobipteryx minuta'' were found. Seven specimens in total were found, including two skeletons in the

redbeds Red beds (or redbeds) are sedimentary rocks, typically consisting of sandstone, siltstone, and shale, that are predominantly red in color due to the presence of ferric oxides. Frequently, these red-colored sedimentary strata locally contain th ...

of Khermeen Tsav in Mongolia's Gobi Desert. These embryos made up the second confirmed embryonic fossils from before the Quaternary Period as well as the first confirmed postcranial fossils of ''G. minuta'' found.

References

{{Taxonbar, from=Q5575539 Euenantiornitheans Late Cretaceous birds of Asia Djadochta fauna Gobi Desert Fossil taxa described in 1974