Xingxiulong (meaning "Xingxiu Bridge dragon") is a genus of bipedal massopodan sauropodomorph from the Early Jurassic of China. It contains two species; the type species is X. chengi, described by Wang et al. in 2017 from three specimens, two adults and an immature individual, that collectively constitute a mostly complete skeleton. Adults of this species measured 4–5 metres (13–16 ft) long and 1–1.5 metres (3.3–4.9 ft) tall. A second species, X. yueorum, was described by Chen et al. in 2025 based on a partial articulated postcranial skeleton of an adult individual larger than X. chengi. Phylogenetic analysis suggests that Xingxiulong is most closely related to its contemporary Jingshanosaurus, although an alternative position outside of both the Sauropodiformes and Massospondylidae is also plausible. Despite their close relationship, Xingxiulong prominently differs from Jingshanosaurus—and from most basal sauropodomorphs—in having a number of sauropod-like traits. These include a sacrum containing four vertebrae; a pubis with an exceptionally long top portion; and the femur, the first and fifth metatarsals on the foot, and the scapula being wide and robust. These probably represent adaptations to supporting high body weight, in particular a large gut. Unlike sauropods, however, Xingxiulong may have still been bipedal.
Discovery and naming
LFGT-D0002, the mature holotype specimen of Xingxiulong chengi, consists of a partial skull with jaws; the seventh to ninth cervical vertebrae, the eighth to fourteenth dorsal vertebrae, the entire sacrum, and 35 caudal vertebrae; rib and chevron fragments; the left ilium, and parts of both pubes and ischia; both femora and tibiae, parts of the fibula, the left ankle, and both feet (nearly complete). Two specimens were referred to X. chengi. LFGT-D0003, also mature, consists of a partial skull with jaws; the third to tenth cervical vertebrae, as well as all of the dorsal vertebrae and most of the sacrum; rib and chevron fragments; both scapulae, humeri, ulnae, and radii, as well as part of the hand; parts of both ilia (the right one is complete) and pubes (the left one is complete); the left femur, parts of both tibiae and fibulae (the right ones are complete), as well as the right ankle and parts of the feet. LFGT-D0001, which is smaller and probably immature, consists of the axis, the third to tenth cervical vertebrae, all of the dorsal vertebrae and sacrum, and the first nineteenth caudal vertebrae; rib and chevron fragments; the right scapula and ilium, as well as parts of the right pubis and ischium; parts of the femora and left tibia, along with the left ankle.
These specimens were discovered, buried together, near the Sankeshu Village of Lufeng County, Yunnan, China in 2013, and are stored at the Bureau of Land and Resources of Lufeng County. The rocks that these specimens were preserved in, consisting of purple silty mudstone, belong to the Early Jurassic Shawan Member of the Lufeng Formation, which has been tentatively dated to being Hettangian in age. Xingxiulong was described in 2017 by Ya-Ming Wang, Hai-Lu You, and Tao Wang. The generic name (literally meaning "constellation") refers to the Xingxiu Bridge (星宿), which was constructed during the Ming Dynasty of China. Meanwhile, the specific name chengi honours Professor Zheng-Wu Cheng, who made major contributions to the biostratigraphy of China, including that of the Lufeng area, and died in 2015. In 2025, Xiang-Yuan Chen, Ya-Ming Wang, Qian-Nan Zhang, Tao Wang & Hai-Lu You described LF2015-NO01 as the holotype of a second species of Xingxiulong, X. yueorum. The specimen consists of most of a articulated postcranial skeleton, including 13 dorsal vertebrae, 11 paired ribs, four sacral vertebrae, 20 caudal vertebrae and associated chevrons, part of the left scapula, and both pelvic girdles and hindlimbs. It was discovered by the Bureau of Natural Resources of Lufeng City in 2015 in outcrops of the Zhangjiaao Member of the Lufeng Formation. These sediments are located in Erzuanshan, Yunnan Province. The specific name honors the siblings of Shu-Yong Yue for their work in collecting and preparing Lufeng dinosaur fossils, including the X. yueorum.
Description
Size
Xingxiulong was a medium- to large-sized sauropodomorph. Adults of X. chengi are estimated at 4–5 metres (13–16 ft) long and 1–1.5 metres (3.3–4.9 ft) tall at the hip. The two larger specimens, LFGT-D0002 and LFGT-D0003, are adults judging by the complete fusion in their skull; the third specimen, LFGT-D0001, is 14% smaller and probably represents a subadult judging by the incomplete fusion in the vertebrae. The holotype of X. yueorum is larger than adult specimens of X. chengi and is estimated to have been 8–10 metres (26–33 ft) long in life; the longest femur of X. chengi is about 56 centimetres (22 in) long, while the femur of X. yueorum is 78 centimetres (31 in) long.
Skull and jaw
… excerpt ends here. Continue reading the full article.
