Caudipteryx (which means "tail feather") is a genus of peacock-sized theropod dinosaurs that lived in the Aptian age of the early Cretaceous Period (about 124.6 million years ago). They were feathered and remarkably birdlike in their overall appearance.[1]
Two species have been described; C. zoui (the type species), in 1998,[1] and C. dongi, in 2000.[2][3]
The discovery of Caudipteryx led to many intensive studies on and debate over the relationship of birds and dinosaurs. The possible positions in the debate can be summarized as follows: Caudipteryx is either a member of the Oviraptorosauria, a bird, or both.
History[]
Caudipterix fossils have been found in sediments of a former lake in Liaoning Province, China. The remains were found in the Sihetun area near the city of Beipiao, in the Jiulongsong Member of the Chaomidianzi Formation, part of the Jehol Group. This underlies the Yixian Formation, which has been determined to be Late Jurassic to Early Cretaceous in age. 1 This genus was named and identified by Philip Currie, Ji Qiang, Mark Norell and Ji Shuan based on the holotype NGMC 97-4-A , a feathered skeleton, and the paratype NGMC 97-9-A . Two species have been described, first C. zoui , in 1998, is considered the type species 1 , and C. dongi , based on IVPP V.12344 , a partial skeleton of an incomplete individual with nearly complete forelimbs, hindlimbs, pelvis, and feather impressions, was found in Zhangjiagou, Sihetun, in 2000. The fossil was collected in the summer of 1998 by the team of the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences. The specimen is from the Yixian Formation in Zhangjiagou locality about 3 kilometers from the famous site of Bepiao, Liaoning Province in northeast China. It is a nearly complete skeleton with feather impressions and better articulated than the two C. zoui specimens.
The discovery of Caudipteryx led to one of the largest studies of the relationships between birds and dinosaurs. This debate led to several conclusions that can be summarized in these points: Caudipteryx is either a member of the Oviraptorosauria, or a bird, or both, and birds may or may not be dinosaurs. Because Caudipteryx possesses indisputable pennaceous feathers, like modern birds, and because many cladistic analyses consider it a non-avian, oviraptorid dinosaur, it provides at the time of its description one of the strongest pieces of evidence that birds descended from dinosaurs. Lawrence Witmer said:
“The presence of indisputable feathers on an indisputable non-avian theropod had the force of an atomic bomb, removing any doubt about the relationships between birds and theropods.” However, not all scientists support the theory that Caudipteryx is an indisputable non-avian, and some doubt the consensus among paleontologists such as Alan Feduccia, who argues that birds are theropods and Caudipteryx is a flightless bird unrelated to dinosaurs. Jones et al. in 2000 found Caudipteryx to be a bird based on mathematical comparisons of body proportions between flightless birds and non-avian theropods. Dyke and Norell in 2005 criticized these analyses and came up with the opposite results. Other researchers such as Zhou, not involved in the debate on the origins of birds, consider the relationships of Caudipteryx to be debatable.
Description[]

Size comparison of Caudipteryx species to a human.
Caudipteryx, like many other maniraptorans, has an interesting mix of reptile- and bird-like anatomical features. Overall, the two Caudipteryx species grew up to 1 metre in length and 0.7 metres in height, and weighed 6–7 kilograms (13–15 lb), the same as a large peacock. The features of the skull, arms, and hips indicate that it was an advanced theropod, but it had a complete covering of feathers, including wing-like arms and an elaborate fan-like tail. The anatomical features of this dinosaur were very notable. This coelurosaur had a strong beak, feathered tail and arms, a small skull, a light skeleton, and long fingers with sharp claws.
Caudipteryx had a short, boxy skull with a beak-like snout that retained only a few tapered teeth in the front of the upper jaw. The tooth crowns were needle-like with the roots of the teeth five times wider than the visible part of the teeth. It had a stout trunk, long legs and was probably a swift runner. Caudipteryx had 12 cervical vertebrae, 9 thoracic vertebrae and 22 tail vertebrae. The ribs have hooked extensions, another characteristic of birds.
Caudipteryx has a short tail stiffened toward the tip, with few vertebrae, like in birds and other oviraptorosaurs. 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). The arms were slender and the hand showed 3 fingers, the first metatarsal being only 40% longer than the second. It has a hand skeleton with a reduced third finger, like that of primitive birds and the oviraptorid Ingenia. the ungual, the claw bone, being missing. The socket of the hip joint, acetabulum, was large and almost a quarter of the length of the ilium. In birds, the acetabulum is only 11% of the length of the ilium. The hind legs were slender and more than twice as long as the arms, the metatarsal bones being elongated.
Caudipteryx did not have very long arms , but its hind legs were. This dinosaur was a runner and probably very fast, although its speed has not been formally calculated. It has been suggested that Caudipteryx did not use its speed to catch prey but to escape from large predators.
Its tail was very short compared to that of any other non-avian dinosaur. This affected the way the legs were held and the small space for the caudofemoralis. As in other maniraptorans, the knee muscles became very important. As its tail became smaller and heavier over time, the upper body became heavy. The femur may have been held horizontally rather than vertically to help bring the legs forward and balance the body. Given these features, Caudipteryx was able to run in ostrich-like patterns.
The shape of the feather and the overall structure of the body show that caudipteryx was not a flightless creature but a terrestrial creature. The long feathers may have been brightly coloured but only to be displayed to scare off enemies or to attract a mate.
Caudipterix 's body was covered in silky, padded feathers, probably used to protect itself from the cold. It seems likely that Caudipterix was homeothermic, "warm-blooded," and therefore produced its own body heat. Insulation against the cold would have been important for this dinosaur, as it is for living birds.
Feathers[]

Wing reconstruction and feather impressions of Caudipteryx sp. (a) and C. dongi (b)
The hands of Caudipteryx supported symmetrical, pennaceous feathers that had vanes and barbs, and that measured between 15–20 centimeters long (6–8 inches). These primary feathers were arranged in a wing-like fan along the second finger, just like primary feathers of birds and other maniraptorans. No fossil of Caudipteryx zoui preserves any secondary feathers attached to the forearms, as found in dromaeosaurids, Archaeopteryx and modern birds. Either these arm feathers are not preserved, or they were not present on Caudipteryx in life. An additional fan of feathers existed on its short tail. The shortness and symmetry of the feathers, and the shortness of the arms relative to the body size, indicate that Caudipteryx could not fly.
The body was covered in a coat of short, simple, down-like feathers. The tail of Caudipterix was like a large fan of feathers that reached up to 2 decimeters in length and spread out from the short bones of its tail and acted as stabilizers when it ran. The tail feathers were similar to the feathers that they had along their arms.
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.
Paleobiology[]
Diet[]

Gastroliths in stomach region of C. zoui specimen BPV 085, National Museum of Natural Science
Caudipteryx is thought to have been an omnivore. In at least two specimens of Caudipteryx (NGMC 97 4 A and NGMC 97 9 A), gastroliths are preserved. As in some herbivorous dinosaurs, the avialan Sapeornis, and modern birds, these gastroliths remain in the position where the animals’ gizzards would have been. It had a bird-like beak lined with long upper teeth. Its strong, hooked beak was used to catch and eat prey, but it needed gastroliths to grind food in the stomach, perhaps because the beak was not developed enough to fully grind food. Caudipteryx fed mainly on insects, small mammals, primitive birds, and lizards.
Classification[]

Skeletal restorations of three specimens

Life restoration
The consensus view, based on several cladistic analyses, is that Caudipteryx is a basal (primitive) member of the Oviraptorosauria, and the oviraptorosaurians are non-avian theropod dinosaurs. Incisivosaurus is the only oviraptorosaur that is more primitive. Halszka Osmólska et 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 that Caudipteryx 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's Vertebrate Paleontology (2005). The view that Caudipteryx was secondarily flightless is also preferred by Gregory S. Paul, Lü et al., and Maryańska et al. Others, such as Stephen Czerkas and Larry Martin have concluded that Caudipteryx is not a theropod dinosaur at all. They believe that Caudipteryx, like all maniraptorans, is a flightless bird, and that birds evolved from non-dinosaurian archosaurs.
In describing Anzu wyliei , a member of the family Caenagnathoidea, Lamanna et al. performed a cladistic analysis with its subsequent cladogram placing Caudipteryx within Oviraptorosauria.
Oviraptorosauria |
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Paleoecology[]
All Caudipteryx fossils were recovered from the Yixian Formation in Liaoning, China. Specifically, they come from a small area of the Jianshangou bed, near the town of Zhangjiakou. They appear to have been fairly common, though isolated to this small region. The specific region in which Caudipteryx lived was home to the other feathered dinosaurs Dilong and Sinornithosaurus.
JPInstitute.com Description[]
Caudipteryx is one of several types of feathered dinosaurs recently discovered in China. These new finds have caused one of the greatest controversies in modern paleontology. They have many of the characteristics that were expected in a "missing link" between dinosaurs and birds, but they lived millions of years after Archaeopteryx, the first known bird ancestor.
Caudipteryx was a turkey-sized dinosaur that had feathers, but was unable to fly. It had short forelimbs, large eyes and long, sharp, spiked teeth. Quick and agile, it had long slender legs. The most prominent feature of Caudipteryx had to be its tail, which was covered with 6-inch-long tail feathers. The feather fossils show bands of dark and light that may have been color, giving us an idea of how Caudipteryx looked.
Some of the evolutionary advantages feathers may have provided to a flightless animal may include the ability to control body heat, some lived in a wetland area, it is easy to imagine it wading into shallow water on its long legs to spear small fish and amphibians with its long sharp teeth. All known remains of Caudipteryx have been found with gastroliths, or "gizzard stones" about an inch in size. This indicates Caudipteryx did not chew its food, probably swallowing small prey whole.
Did Archaeopteryx and Caudipteryx descend from a common ancestor? Or was Caudipteryx a dinosaur sharing a convergent evolution with birds. This will be a long and lively debate.
Dinosaur Field Guide Description[]
Caudipteryx ("'tail feathers") was one of the most amazing dinosaur discoveries of the 20th century. It showed a dinosaur that was not a bird but had true feathers on its arms and tail. Some scientists thought Caudipteryx was no more than some kind of primitive flightless bird, but when the skeleton of this little creature was studied in detail, it turned out to be an oviraptorosaur. Oviraptorosaurs were a type of meat-eating dinosaur common in the Late Cretaceous of Asia and North America. Caudipteryx was the oldest of the oviraptorosaurs and one of the most primitive. The arms of Caudipteryx were very short, so it certainly could not fly. Then why did it have feathers? Paleontologists suggest a number of possibilities. It might be that they were used for signaling other Caudipteryx, as a peacock does. They might have been used to cover Caudipteryx's eggs while it brooded its nest. Or possibly the ancestors of Caudipteryx really did fly but later become grounded (as happened with ostriches, kiwis, and chickens). We may never know for sure.
Fun Facts[]
Some Caudipteryx fossils have been found with stomach stones, which would have helped grind up thair food,
Trivia[]
One of the newest dinosaur museums in the world is being built in China next to the site where Caudipteryx and other feathered dinosaur fossils were found.
Gallery[]
Links[]
- ↑ 1.0 1.1 Ji, Q., Currie, P.J., Norell, M.A., and Ji, S. (1998). "Two feathered dinosaurs from northeastern China." Nature, 393(6687): 753–761. Template:DOIPDF fulltext
- ↑ Zhou, Z., and Wang, X. (2000). "A new species of Caudipteryx from the Yixian Formation of Liaoning, northeast China." Vertebrata Palasiatica, 38(2): 113–130. PDF fulltext
- ↑ Zhou, Z., Wang, X., Zhang, F., and Xu, X. (2000). "Important features of Caudipteryx - Evidence from two nearly complete new specimens." Vertebrata Palasiatica, 38(4): 241–254. PDF fulltext