Caihong
Caihong | |
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The holotype of Caihong juji, PMoL-B00175 | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | Saurischia |
Clade: | Theropoda |
Family: | †Anchiornithidae |
Genus: | †Caihong Hu et al., 2018 |
Type species | |
†Caihong juji Hu et al., 2018
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Caihong (
Discovery and naming
At Gangou, Qinglong, in the north of Hebei province, peasant Yang Jun discovered in a quarry near the village of Nanshimenzi the skeleton of a small theropod, belonging to the Yanliao Biota. It was in February 2014 acquired by the Paleontological Museum of Liaoning. The fossil was subsequently, and for the first time, prepared by Ding Xiaoqing and Matthew Brown.[1]
In 2018, the type species Caihong juji was named and described by Hu Dongyu, Julia A. Clarke, Chad M. Eliason, Qiu Rui, Li Quanguo, Matthew D. Shawke, Zhao Cuilin, Liliana D'Alba, Jiang Jinkai and Xu Xing. The generic name is the Mandarin caihong, 彩虹, "rainbow", in reference to the splendor of the fossil and the spectrum of new scientific insights it offers. The specific name is the Chinese ju ji, "big crest", in reference to the large crest on the lacrimal bone of the skull.[1]
The holotype, housed at the Paleontological Museum of Liaoning with the accession number PMoL-B00175, was found in a layer of the Tiaojishan Formation dating to the Oxfordian, about 161 million years old. It consists of a complete articulated skeleton, compressed on a slab and counterslab. Soft tissues and extensive remains of the plumage have been preserved. It represents an adult individual.[1]
Description
Size and distinguishing traits
Caihong was a rather small dinosaur. Its length was estimated at 40 cm (16 inches), and its weight at 475 grams (16.8 oz).[1] It is estimated to have a wingspan of approximately 44 cm (17 in), given that the wingspan is about 2.1 times the wing length which is about 21 cm (8.3 in).[2]
The describing authors indicated a number of unique derived traits,
Besides, Caihong was especially distinguished from closely related
Skeleton
The skull of Caihong has a length of 67.6 millimetres. It is low and elongated (superficially similar to that of Velociraptor), only slightly shorter than the femur. The nostril is large and oval-shaped. The elliptical maxillary fenestra, an opening in front of the antorbital fenestra, is large and located in the middle of the antorbital fossa. The antorbital fenestra itself only occupies 40% of the length of this depression. These fenestrae are augmented by a rather large promaxillary fenestra at the front of the antorbital fossa, similar to that of Archaeopteryx, as well as an additional smaller opening (an accessory fenestrae) slightly lower than the promaxillary fenestra, between it and the maxillary fenestra. The strut separating the maxillary fenestra from the antorbital fenestra is pierced by a connecting channel, a typical troödontid trait. The eye socket is longer than high. In front of this orbit, the lacrimal bone has a long and robust horn-like process, oriented sideways at its base and gradually curving upwards at its tip.[1]
The generally recurved teeth are more slender and tightly packed in the front of the jaws, such as in the
Caihong probably has ten neck vertebrae, thirteen back vertebrae, five sacral vertebrae and 26 tail vertebrae. The dorsal vertebrae of the back do not possess
The arm is relatively short, equal to 60% of the hindlimb length. Especially the
In the pelvis, the blade of the ilium is long before the position of the hip joint, but short and slightly curved downwards behind it. The
The hindlimb is very long, 3.1 times as long as the torso. The thighbone is elongated and has a length of 70.9 millimetres. The shinbone is approximately 82 millimetres long. It is fused with the upper ankle bones into a tibiotarsus. The third
Feathering and coloration
The fossil is surrounded by a wide zone of feathers, only the snout and claws being uncovered. These feathers are not impressions but remains of the original plumage. The splitting of slab and counterslab revealed a complex layering of the plumage. The density of visible shafts and barbs is so extreme that it is difficult to identify individual feathers. The way they are presently preserved may not represent their original condition and position.[1]
The body contour feathers of Caihong are relatively longer than those of other non-avian dinosaurs. Skull and neck show two types of them: the first is stiff, two centimetres long and elongated; the other has a length of one centimetre and is more wavy. On the breast and limbs, four centimetres long feathers are visible with parallel straight and thick barbs. None of these contour feathers could be definitely identified as being pennaceous, with closed vanes.[1]
The fossilized feathers of Caihong possessed nanostructures which were analyzed and interpreted as