東アジア最古の竜脚形類恐竜を発見(Chinese Researchers Discover East Asia’s Oldest Sauropodomorph Dinosaur)

2025-08-07 中国科学院(CAS)

中国科学院古脊椎動物・古人類研究所(IVPP)などの研究チームは、中国雲南省武定県の下部ジュラ紀地層から、東アジア最古の竜脚形類恐竜「武定龍(Wudingloong)」を発見した(Scientific Reports掲載)。2020年に発見された化石は頭骨、頸椎・背椎、前肢骨が良好に保存されており、系統解析と地層年代から約2億年前の最初期ジュラ紀に生息した最古の竜脚形類であることが判明。東アジアの他種に比べ小型で、滑らかな歯のエナメル質、細長い肩甲骨、上腕骨に対する橈骨比の高さ、長い指などから二足歩行だった可能性が高い。新たな系統解析マトリックスも構築され、この発見は中国南西部の竜脚形類群集が世界的にも初期ジュラ紀で最も多様性と形態的変異に富むことを裏付ける。

<関連情報>

東アジアで最も早期に分岐し、最も古いサウルポドモルフを表現する新しい早期ジュラ紀の恐竜 A new Early Jurassic dinosaur represents the earliest-diverging and oldest sauropodomorph of East Asia

Ya-Ming Wang,Qian-Nan Zhang,Yan-Chao Wang,Huan Xu,Jianbo Chen,Zhuo Feng,Xing Xu,Tao Wang & Hai-Lu You
Scientific Reports  Published:23 July 2025
DOI:https://doi.org/10.1038/s41598-025-12185-2

東アジア最古の竜脚形類恐竜を発見(Chinese Researchers Discover East Asia’s Oldest Sauropodomorph Dinosaur)

Abstract

A new dinosaur assemblage from the Lower Jurassic at Wande Town, Wuding County, Yunnan Province, China is discovered recently. Here a new sauropodomorph from this site, Wudingloong wui gen. et sp. nov., is described on the basis of a partial skeleton. Wudingloong is different from other non-sauropodiform sauropodomorphs particularly in having an ascending ramus of the maxilla excavated by triangular antorbital fossa, distinct ventral keel on the middle cervical centra, a slender humerus with a flat and low humeral head, a gracile metacarpal V with the proximal end as wide as the distal end, and a large and robust ungual of manual digit I. Wudingloong was excavated from the lowest Lower Jurassic Yubacun Formation, which is the lowest dinosaur bone bed in East Asia. Both the phylogenetic analysis and stratigraphic horizon indicate that Wudingloong represents the earliest-diverging and stratigraphically oldest sauropodomorph dinosaur discovered in East Asia so far. The discovery of this new taxon provides further evidence that the southwestern China sauropodomorph assemblage is one of the most taxonomically diverse and morphologically disparate in the pre-Toarcian Early Jurassic worldwide, represented by various taxa from near the base of the Massopoda to non-sauropodan sauropodiforms.

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