Keichousaurus hui,

a fossil marine reptile from the Triassic of China.

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Figs. 1-2: a superb specimen of Keichousaurus hui, and label. These are very small reptiles, often less than 30 cm in length. These specimens (Figs. 1 and 3) are beautifully preserved, and prepared with great skill and care. The specimens shown here are in the vertebrate palaeontology display of the Yifu Museum, China University of Geosciences - Beijing, Haidian campus. Photos taken in April 2018 and April 2019.

"Rock of the Month # 229, posted for July 2020" ---

This genus of reptile, a pachypleurosaur, was first discovered in China in 1957 by the versatile scientist Hu Zhengzhi (1917-2018) and the species is named in his honour. The name of the genus is derived from the old Wade-Giles transliteration Kweichow, the home of the type locality is what is now (pinyin transliteration) known in English as Guizhou province, south China. Guizhou is a landlocked province, south of the Yangtze River's course as it passes Chongqing in Sichuan. Variations in transliteration can be ascribed to the efforts to standardize translation of Chinese scripts prior to the development of the pinyin system in the 1950s.

Keichousaurus is preserved in strata dated to the uppermost Middle Triassic (Ladinian stage) to Upper Triassic (Norian stage, circa 227 to 209 Ma) in China and Mongolia. Its family belongs to a Triassic group of marine reptiles named the sauropterygians. Much early work on Chinese dinosaurs was carried out by famed vertebrate palaeontologist Yang Zhongjian (1897-1979),whose name often appears in anglicized form as Chung Chien Young, or simply C-C Young .

The tiny fossils of this genus, often found as complete skeletons, are understandably popular with collectors, and appear to have spawned a home industry in specimens. They are the smallest known examples of such marine reptiles. With their long necks and elongate heads, these were evidently fish-eating predators. The adorable Keichousaurus hui have been nicknamed the "Guizhou dragon". The samples are from Guanling, southwest of Guiyang in western Guizhou. The adults are some 30 cm long. It has been suggested, from their anatomy, that they may have given birth to live young. Fossils of tiny offspring are as small as 3 cm in length. The number of extant skeletal remains is sufficient that paleobiologists have even been able to make inferences about the population represented in museum collections and publications (Mottani et al., 2015). That study was based on 86 specimens, 27 from a single quarry in Nimaigu village, Xingyi City (Huangcaoba), near the Yunnan border in southwest Guizhou. The authors found that the available sample population was some 60% female, suggesting higher mortality of males. It was inferred that the males tended to have larger, more robust forelimbs. Perhaps, then (with a non-expert eye) we can suggest that the individual in Figure 1 is male, and the one in Figure 3 a female (?). These early marine reptiles became extinct at the end of the Triassic period, though some relatives persisted throughout Mesozoic time.

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Fig. 3: a second specimen of Keichousaurus hui.


Museo Geominero, Madrid (2015) and CUGB Yifu Museum, Beijing (2016-2019)

The superb Museo Geominero (Rios Rosas, 23, Madrid, Spain, visited April 2015) presents fossils in both stratigraphic and taxonomic sequences (similar care is taken with minerals, such that the museum is a marvellous tool for geological education). Fossils from around the world include examples from China, such as the orthocerid cephalopod Sinoceras, from the Upper Ordovician of the Three Gorges, a small (20-cm) Nothosaurus ("false lizard", a sauropterygian from Guizhou) and, yes, a Keichousaurus hui.

In Beijing, the CUGB's Yifu Museum (many visits, 2016-2019) displays at least a dozen species of early reptile and later dinosaur, including spectacular ankylosaurs (a future "Rock" of the Month?) such as Crichtonsaurus and the larger Zhejiangosaurus, ornithopods, early bird-like fossils, crocodilian creatures, and some of the smaller variants of sauropod. The precursor to the Yifu Museum was the museum of the Beijing College of Geology, founded in 1952. There are now some 60,000 samples, with 5,000 on current display, from China and over 40 countries worldwide (Anon, 2016). The original material came from the geology departments of Peking University, Tsinghua University, Tianjin University and Tangshan Railway Institute.


Anon (2016) The Museum of China University of Geosciences. Yifu Museum, China University of Geosciences - Beijing, Haidian district, Beijing., 106pp. (in Ch. and in Engl.).

Motani,R, Jiang,D-Y, Rieppel,O, Xue,Y-F and Tinton,A (2015) Adult sex ratio, sexual dimorphism and sexual selection in a Mesozoic reptile. Proc.Roy.Soc. B282, 7pp.

Graham Wilson, 09-10 May 2020.

Read more about this interesting fossil at Wikipedia,

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"Rock of the Month Index"
(specimens related to China, and Beijing, appear below).
Provenance of specimens:
CAGS = China Academy of Geological Sciences, Beijing
CUGB = China University of Geosciences, Beijing (Grounds and Yifu Museum)
NGMC = National Geological Museum of China, Beijing
TGSL = Turnstone / Wilson collection
Various = Other private collections
YMY = Yuanmingyuan, Old Summer Palace, Beijing

Class/Group/Family 15 Topics across China --- 中国 (Zhong guo) --- such as samples in Beijing museums Site
The "Rock of the Month"
Tektite (glass) ---- #55 --- Tektites from Guangdong, China TGSL
Feldsparphyric ornamental "peony" stone --- #178 --- Porphyritic metabasite from Henan, China CUGB
Rapakivi granite (building stone) --- #179 --- Textures in a rapakivi granite, Beijing, China CUGB
Arsenic ore minerals --- #180 --- Arsenic sulphides, realgar and orpiment, from (?) Hunan, China CUGB
Superb crinoid fossils --- #181 --- Traumatocrinus, exceptional crinoid fossil from Guizhou, China NGMC
Beryl, beryllium cyclosilicate, gemstone --- #186 --- Prismatic beryl from (?) Yunnan, China CUGB
Vertebrate fossil, historically significant --- #201 --- Mesosaurus, fossil reptile & mascot for Gondwanaland (Brazil, via Guangxi, China) CUGB
Ornamental carving stone, China --- #203 --- Qingtian stone, superb lapidary material from Zhejiang, China CUGB
Ophiolitic chromitite --- #205 --- Chromitite, Luobusa ophiolite, southern Tibet (Xizang, China) CAGS
Nephrite jade --- #207 --- Massive jade as decorative piece, from China Various
Peridotite xenoliths in basalt --- #217 --- Mantle nodules and megacrysts, Hebei, China TGSL / CAGS
Tempestite dolostone of Jixian age --- #219 --- Tempestite with algal mats, Tianjin, China CUGB / YMY
Foraminifera from Java, Indonesia --- #226 --- Nummulite fossil Camerina CUGB
Orange barite on quartz --- #228 --- Barite, Xiefang mine, Jiangxi province, China TGSL
Vertebrate fossil --- #229 --- Keichousaurus hui, fossil reptile,China CUGB