Chaoyangsaurus Temporal range: Late Jurassic, | |
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Skeletal restoration showing known material | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | † Ornithischia |
Clade: | † Neornithischia |
Clade: | † Ceratopsia |
Family: | † Chaoyangsauridae |
Genus: | † Chaoyangsaurus Zhao, Cheng, & Xu, 1999 |
Species: | †C. youngi |
Binomial name | |
†Chaoyangsaurus youngi Zhao, Cheng, & Xu, 1999 | |
Chaoyangsaurus ("Chaoyang lizard") is a marginocephalian dinosaur from the Late Jurassic of China. It has been dated to between 150.8 and 145.5 million years ago. [1] Chaoyangsaurus belonged to the Ceratopsia (Greek for "horned faces"). Chaoyangsaurus, like all ceratopsians, was primarily a herbivore. [2] [3]
In 1976, the remains of Chaoyangsaurus were found by Cheng Zhengwu at Ershijiazi, in the Chaoyang area of Liaoning Province in northeastern China. The fossil was added to a travelling exhibition.
Unlike many other dinosaurs, Chaoyangsaurus had been discussed in a number of sources before its official publication. As a result of this, several different spellings of its name have come and gone as invalid nomina nuda ("naked names", names with no formal description behind them). The first name to see print was Chaoyoungosaurus, which appeared in the guidebook to a Japanese museum exhibit, and was the result of an incorrect transliteration from the Chinese into the Latin alphabet. Zhao Xijin in 1983 also used this spelling when he first discussed the species, [4] again lacking a description so it is technically a nomen nudum. Two years later, Zhao again used this early spelling when he assigned a type specimen and species name, Chaoyoungosaurus liaosiensis. [5]
According to Dong Zhiming in 1992, the name Chaoyoungosaurus had been officially described in a separate paper by Zhao and Cheng in 1983, but no cite for this paper was given, and later Cheng and Zhao themselves did not treat this name as valid, perhaps because the paper had not actually been published. Dong, in his 1992 book on Chinese dinosaur faunae, also emended the name to the "correct" spelling of Chaoyangosaurus (note the extra letter "o"). [6] However, since this renaming was not accompanied by a formal description of the dinosaur, Chaoyangosaurus must be considered a nomen nudum also.
It was not until 1999 that the dinosaur finally received an official name. Paul Sereno in 1999 used the name Chaoyangsaurus in an overview of dinosaurian evolution. [7] Once again, that name was a nomen nudum. However, in December of that year, Cheng, Zhao, and Xu Xing published an official description using the name Chaoyangsaurus youngi, and as the first name for this genus that is not a nomen nudum, it has official priority over all other spellings that have been used. The generic name refers to Chaoyang. The specific name honours the Chinese paleontologist Yang Zhongjian ("C. C. Young") as the founder of Chinese vertebrate paleontology. [8]
The holotype, IGCAGS V371, has been found in a layer of the Tuchengzi Formation that was in 1999 dated to the late Tithonian. It consists of a partial skeleton with skull. It contains the lower part and braincase of the skull, the lower jaws, seven neck vertebrae, the right shoulder blade and the right humerus. It represents an adult individual. The fossil was prepared by Ding Jinzhao and Wang Haijun. [8]
In 2010, Gregory S. Paul estimated the length of Chaoyangsaurus at one metre, the weight at six kilogrammes. [9]
The describing authors indicated some distinguishing traits. The boss on the jugal bone is only weakly developed and has a smooth surface. The convex quadratojugal bone overlaps the rear of the shaft of the quadrate bone. The quadrate lacks a wide side surface, not being expanded to the front. The rear lower edge of the quadrate is convex. The coronoid process of the lower jaw is low with a flat top. The planes of the side surface and the underside of the angular bone are separated by a ridge. The last five traits were considered autapomorphies. [8]
The skull is fourteen centimetres long. Per side, the appending lower cutting edge of the rostral bone, in life probably covered by horn, bears four crenulations. More to the rear, there are two conical premaxillary teeth, jutting out to below. The transversely flattened maxillary teeth number eight or nine, while there are eleven dentary teeth in the lower jaw for a maximal total of forty-four teeth for the head as a whole. The cheek teeth are imbricated and vertically rather long. Both inner and outer sides are covered by enamel. [8]
In 1999, Chaoyangosaurus was placed in the Ceratopsia, in a basal position. There were doubts whether it was outside or inside the Neoceratopia. [8]
In 2006, Zhao, et al defined a Chaoyangsauridae, as the most basal ceratopian clade. [10]
Mamenchisaurus is a genus of sauropod dinosaur known for their remarkably long necks which made up nearly half the total body length. Numerous species have been assigned to the genus; however, the validity of these assignments has been questioned. Fossils have been found in the Sichuan Basin and Yunnan Province in China. Several species from the Upper Shaximiao Formation, whose geologic age is uncertain, have been described. However, evidence suggests this formation to be no earlier than the Oxfordian stage of the Late Jurassic. M. sinocanadorum dates to the Oxfordian stage, and M. anyuensis to the Aptian stage of the Early Cretaceous. Most species were medium-large to large sauropods, measuring roughly 15 to 26 meters in length—possibly up to 35 meters (115 ft), based on two undescribed vertebrae.
Ceratopsia or Ceratopia is a group of herbivorous, beaked dinosaurs that thrived in what are now North America, Europe, and Asia, during the Cretaceous Period, although ancestral forms lived earlier, in the Jurassic. The earliest known ceratopsian, Yinlong downsi, lived between 161.2 and 155.7 million years ago. The last ceratopsian species, Triceratops prorsus, became extinct during the Cretaceous–Paleogene extinction event, 66 million years ago.
Yangchuanosaurus is an extinct genus of metriacanthosaurid theropod dinosaur that lived in China from the Middle Jurassic to Late Jurassic periods, and was similar in size and appearance to its North American and European relative, Allosaurus. Yangchuanosaurus hails from the Upper Shaximiao Formation and was the largest predator in a landscape that included the sauropods Mamenchisaurus and Omeisaurus and the stegosaurs Chialingosaurus, Tuojiangosaurus and Chungkingosaurus. This theropod was named after the area in which was discovered, Yongchuan, in China.
Psittacosaurus is a genus of extinct ceratopsian dinosaur from the Early Cretaceous of what is now Asia, existing between 125 and 105 million years ago. It is notable for being the most species-rich non-avian dinosaur genus. Up to 12 species are known, from across China, Mongolia, Russia, and Thailand. The species of Psittacosaurus were obligate bipeds at adulthood, with a high skull and a robust beak. One individual was found preserved with long filaments on the tail, similar to those of Tianyulong. Psittacosaurus probably had complex behaviours, based on the proportions and relative size of the brain. It may have been active for short periods of time during the day and night, and had well-developed senses of smell and vision.
Shantungosaurus is a genus of very large saurolophine hadrosaurid dinosaur found in the Late Cretaceous Wangshi Group of the Shandong Peninsula in China, containing a single species, Shantungosaurus giganteus. The stratigraphic interval of Shantungosaurus ranges from the top of the Xingezhuang Formation to the middle of the Hongtuya Formation, middle to late Campanian in age. Shantungosaurus is so far the largest hadrosauroid taxon in the world, with size estimates around 15–17 metres (49–56 ft) in length and 13–16 metric tons in body mass.
Tianchisaurus, also invalidly called Tianchiasaurus and "Jurassosaurus", is a genus of ankylosaurian dinosaur from the Late Jurassic (Oxfordian–Kimmeridgian)-aged Toutunhe Formation of China. It is one of the oldest ankylosaurs, being slightly younger than the Moroccan Spicomellus. While many later-diverging ankylosaurids had bony clubs at the tips of their tails, Tianchisaurus likely lacked such a structure.
Monolophosaurus is an extinct genus of tetanuran theropod dinosaur from the Middle Jurassic Shishugou Formation in what is now Xinjiang, China. It was named for the single crest on top of its skull. Monolophosaurus was a mid-sized theropod at about 5–5.5 metres (16–18 ft) long and weighed 475 kilograms (1,047 lb).
Lufengosaurus is a genus of massospondylid dinosaur which lived during the Early Jurassic period in what is now southwestern China.
Turanoceratops is a genus of herbivorous ceratopsian dinosaur from the late Cretaceous Bissekty Formation of Uzbekistan. The fossils dated from the mid-late Turonian stage, roughly 90 million years ago. The skull bore a pair of long brow horns like those seen in the Ceratopsidae, although Turanoceratops appears to have been transitional between earlier ceratopsians and ceratopsids, and not a ceratopsid itself.
Xuanhuaceratops is a genus of dinosaur from the Late Jurassic Period. The genus was in 2006 dated to the Tithonian, 150.8-145.5 million years ago. A member of the family Chaoyangsauridae, it was one of the earliest ceratopsians. The fossils were found in the Houcheng Formation of Hebei Province, northeastern China.
Szechuanosaurus is an extinct genus of carnivorous theropod dinosaur from the Late Jurassic. Fossils referred to the genus have been found in China, Asia in the Oxfordian-?Tithonian. Its type species is based on several undiagnostic teeth from the Kuangyuan Series. Additional possible specimens of Szechuanosaurus were also reported from the Kalaza Formation, also located in China.
Chinshakiangosaurus is a genus of dinosaur and probably one of the most basal sauropods known. The only species, Chinshakiangosaurus chunghoensis, is known from a fragmentary skeleton found in Lower Jurassic rocks in China. Chinshakiangosaurus is one of the few basal sauropods with preserved skull bones and therefore important for the understanding of the early evolution of this group. It shows that early sauropods may have possessed fleshy cheeks.
Monkonosaurus is a dubious genus of herbivorous stegosaurian dinosaur from the Late Jurassic/Early Cretaceous-aged Loe-ein Formation of Tibet. Some sources place it as alive during the Oxfordian - Albian stages, around 163 - 100 million years ago, although Monkonosaurus was probably only alive during the Late Jurassic, making it among the earliest known stegosaurs along with Chungkingosaurus and Bashanosaurus.
Yinlong is a genus of basal ceratopsian dinosaur from the Late Jurassic Period of central Asia. By far the earliest known ceratopsian, it was a small, primarily bipedal herbivore.
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Chaoyangsauridae is a family of ceratopsian dinosaurs. They are among the earliest known marginocephalian dinosaurs, with remains dating to about 160 million years ago, during the Late Jurassic period. Members of this group had sharp beaks for snipping off leaves to eat, and a very small frill.
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Hualianceratops is a genus of herbivorous ceratopsian dinosaur that lived about 160 million years ago in the Late Jurassic epoch in what is now western China. The single species, H. wucaiwanensis was described in 2015. Its size has been compared to that of a spaniel.