| Caudipteryx | |
|---|---|
 | |
| MountedCaudipteryx zoui skeleton atLöwentor Museum | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Clade: | †Oviraptorosauria |
| Family: | †Caudipteridae |
| Genus: | †Caudipteryx Jiet al. 1998 |
| Type species | |
| †Caudipteryx zoui Jiet al., 1998 | |
| Other species | |
Caudipteryx (meaning "tail feather") is agenus of smalloviraptorosaurdinosaurs that lived inAsia during theEarly Cretaceous, around 124.6 million years ago. They werefeathered and extremelybirdlike in their overall appearance, to the point that somepaleontologists suggested it was abird. Twospecies have been described:C. zoui (thetype species), in 1998, andC. dongi, in 2000.
It had a stout trunk, long legs and was probably a swift runner. The discovery ofCaudipteryx has led to many intensive studies and debate over the relationship of birds and dinosaurs.
In 1997, several well-preserveddinosaur skeletons were recovered from the Jiulongsong Member of theChaomidianzi Formation (now Jianshangou Bed of theYixian Formation), at the Sihetun locality ofLiaoning province,China. Thefossils were later described in 1998 and used as the type specimens for the new dinosaur taxaCaudipteryx andProtarchaeopteryx.Caudipteryx was erected with the type speciesC. zoui and theholotype is NGMC 97-4-A, a nearly complete individual preserving conspicuous feather impressions andgastroliths. Theparatype is NGMC 97-9-A, another relatively complete individual with feather impressions. Thegeneric name,Caudipteryx, means "tail feather", and thespecific name,zoui, is in honor ofZou Jiahua for his prominent support to the scientific community as thevice premier of China.[1]
Around the summer of 1988, a partially complete skeleton ofCaudipteryx lacking the skull was found in sediments of the "Layer 6" of the Yixian Formation, at the Zhangjiagou locality, which is set apart 3 km (1.9 mi) from Sihetun. This specimen, IVPP V 12344, was in 2000 described and designed as the holotype for new speciesCaudipteryx dongi, and in a similar fashion to previous specimens of the genus, it preserves exquisite traces of feather integument. The specific namedongi honorsZhiming Dong, a Chinesepaleontologist.[2]
During 2000, Zhong-He Zhou and colleagues described two additional specimens ofCaudipteryx, BPM 0001 and IVPP V 12430, referred toC. zoui andC. sp. respectively. Both individuals preserve nearly complete skulls and have feather impressions.[3] Further analyses to IVPP V 12430 have revealed the preservation of propatagium on its left arm.[4]
In 2021 Xiaoting Zheng and team described STM4-3 representing an articulated individual lacking the skull and tail tip, including abundant integument, gastroliths, but also a cartilage fragment that was reported to preservechondrocytes. The specimen was collected from outcrops of the Yixian Formation at Dapingfang Town nearChaoyang city, westLiaoning.[5]
Caudipteryx was a small theropod, measuring 72.5–89 cm (2 ft 4.5 in – 2 ft 11.0 in) long and weighing about 5 kg (11 lb) based on femur length.[1][2][6] Like many othermaniraptorans, has a mix of reptile- and bird-like anatomical features.[7]
It had a short, boxyskull with a beak-like snout that retained only a few tapered teeth in the front of the upper jaw.[2]
Its short tail was stiffened toward the tip, with few vertebrae, like in birds and otheroviraptorosaurs. It has a primitive pelvis and shoulder, and primitive skull details in the quadratojugal, squamosal, quadrate, jugal, and mandibular fenestra (in the cheek, jaw, and jaw joint). It has a hand skeleton with a reduced third finger, like that of early birds and the oviraptoridHeyuannia.[8]
Caudipteryx had uncinate processes on the ribs, birdlike teeth, a first toe which may or may not be partially reversed and overall body proportions that are comparable to those of modern flightless birds.[1][2][7][3][9]
The hands ofCaudipteryx supported symmetrical, pennaceous feathers that had vanes and barbs, measuring between 15 and 20 centimetres (5.9 and 7.9 inches) long. The primary feathers were arranged in a wing-like fan along the second finger, just like primary feathers of birds and othermaniraptorans. An additional fan of feathers existed on its tail. The body ofC. zoui was covered in black feathers, with a visible banding pattern preserved on tail feathers.[10]
A study on the number of flight feathers has concluded thatCaudipteryx was secondarily flightless.[11]
The consensus view, based on severalcladistic analyses, is thatCaudipteryx is a basal (primitive) member of theOviraptorosauria, and the oviraptorosaurians are non-avian theropod dinosaurs.[12]Incisivosaurus is the only oviraptorosaur that is more primitive.[13]
Halszka Osmólskaet al. (2004) ran a cladistic analysis that came to a different conclusion. They found that the most birdlike features of oviraptorids actually place the whole clade within Aves itself, meaning thatCaudipteryx is both an oviraptorid and a bird. In their analysis, birds evolved from more primitive theropods, and one lineage of birds became flightless, re-evolved some primitive features, and gave rise to the oviraptorids. This analysis was persuasive enough to be included in paleontological textbooks like Benton'sVertebrate Paleontology (2005).[14]The view thatCaudipteryx was secondarily flightless is also preferred byGregory S. Paul,[15]Lüet al.,[16] andMaryańskaet al.[17]
Others, such as Stephen Czerkas andLarry Martin have concluded thatCaudipteryx is not atheropod dinosaur at all.[18] They believe thatCaudipteryx, like allmaniraptorans, is a flightless bird, and that birds evolved from non-dinosaurianarchosaurs.[19]
A weighted cladogram from 2014, using TNT, is shown below.[20]
BecauseCaudipteryx has clear and unambiguously pennaceous feathers, like modern birds, and because several cladistic analyses have consistently recovered it as a non-avian oviraptorid dinosaur, it provided, at the time of its description, the clearest and most succinct evidence that birds evolved from dinosaurs.Lawrence Witmer stated:“The presence of unambiguous feathers in an unambiguously non-avian theropod has the rhetorical impact of an atomic bomb, rendering any doubt about the theropod relationships of birds ludicrous.”[7]
However, not all scientists agreed thatCaudipteryx was unambiguously non-avian, and some of them continued to doubt that general consensus. PaleornithologistAlan Feduccia seesCaudipteryx as a flightless bird evolving from earlierarchosaurian dinosaurs rather than from late theropods.[21] Joneset al. (2000) found thatCaudipteryx was a bird based on a mathematical comparison of the body proportions of flightless birds and non-avian theropods. Dyke and Norell (2005) criticized this result for flaws in their mathematical methods, and produced results of their own which supported the opposite conclusion.[9][12] Other researchers not normally involved in the debate over bird origins, such as Zhou, acknowledged that the true affinities ofCaudipteryx were debatable.[3]
_gastroliths.jpg)
Caudipteryx is thought to have been anomnivore. In at least two specimens ofCaudipteryx (NGMC 97 4 A and NGMC 97 9 A),gastroliths are preserved. As in some herbivorous dinosaurs, theavialanSapeornis, and modern birds, these gastroliths remain in the position where the animals'gizzards would have been.[1]
AllCaudipteryxfossils were recovered from theYixian Formation inLiaoning,China. Specifically, they come from a small area of the Jianshangou bed, near the town ofZhangjiakou. They appear to have been fairly common, though isolated to this small region. The specific region in whichCaudipteryx lived was home to the other feathered dinosaursDilong andSinornithosaurus.[22]
Media related toCaudipteryx at Wikimedia Commons
Data related toCaudipteryx at Wikispecies
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