Caudipteryx Ji Qiang, Currie, Norell & Ji Shuan, 1998

Caudipteryx Ji Qiang, Currie, Norell & Ji Shuan, 1998 (Nature (Lond) 393 (6687), 25 June: 754. NcZ) "tail feather"
kaw-DIP-ter-iks or kaw-dip-TAYR-iks (also KAW-dee-tayr-iks, Curries' own pronunciation) (Lat. cauda "tail" + Greek pteryx "wing, feather") (f) named to indicate a turkey-sized (3-ft.long) theropod notable for large symmetrical feathers arranged fanlike on the end of the tail. Caudipteryx is thought to represent a type of feathered ground-living dinosaur that may be related to the Oviraptorosauria. The two known specimens of the genus were found in the Jiulongsong Member of the Chaomidianzi Formation, Sihetun area of Liaoning Province, northeastern China, in ancient lake deposits that preserved impressions of rather large symmetrical shafted feathers on the tail and forelimbs, as well as downlike feathers on the body. However, the relatively small size of the forelimbs, the proportionately large hindlimbs and the symmetrical design of the feathers indicate the animal very likely could not fly. The animal is identified as a dinosaur rather than a bird based on a list of distinctive features, but most importantly, a skull with a bony bar behind the eyes (not found in birds) and other theropod characteristics. The pelvis is theropodlike (similar to dromaeosaurs and oviraptorids): the ischium lacks the posterodorsal process found in Archaeopteryx and other birds. Additionally, the hallux (first digit on the foot) is reduced and positioned high on the metatarsals, off the ground and oriented outward and slightly forward, as in typical theropod dinosaurs; by constrast, the hallux in most birds, including Archaeopteryx, is well-developed, low on the metatarsals and positioned backwards for perching or contact with the ground.
The two specimens were originally assigned to Protarcheopteryx. However, Caudipteryx differs from Protarchaeopteryx: its jaws are toothless except for usual hooked spike-like teeth at the tip of the upper jaw (premaxillary) that were probably partly covered with a horny beak; its tail is relatively short (one-quarter the length of the body, with 22 vertebrae (as in Archaeopteryx)); the forelimbs are relatively long for a nonavian theropod but shorter than in Protarchaeopteryx, with large secondary feathers attached to the second digit on the hand; it has a gizzard containing small grinding stones, indicating it may have eaten plant material.
Recent studies suggest Caudipteryx may be related to oviraptorosaurs. A few researchers have challenged the identification of Caudipteryx as a theropod dinosaur and propose that it is a secondarily flightless plant-eating bird that evolved from primitive Archaeopteryx-like forms.
Type species: Caudipteryx zoui [DZOH-ie] "Zou's tail-feather" to honor Zou Jaihua, vice-premier of China, for his support of scientific work in Liaoning. Theropoda Maniraptora E. Cret. China [revised 6/99]

Видовой состав

Документы

Иллюстрации без комментариев