A five-year investigation into fossils from Wuding County in Yunnan Province, China, uncovered the oldest sauropodomorph dinosaur in East Asia and the earliest hard-shelled eggs linked to that lineage. The species, named Wudingloong Wui, is represented by three nearly complete adult skeletons and five egg clutches with embryos recovered from Lower Jurassic rocks near Wande Town.
The assemblage surfaced in 2020 when construction workers exposed bones in the area’s Lower Jurassic strata. Teams from the Institute of Vertebrate Paleontology and Paleoanthropology, the Geological Museum of China, Yunnan University and the county natural resources bureau excavated the site and spent five years restoring the material. Their findings appeared in the journal Scientific Reports.
The fossils include cranial elements, vertebrae and forelimb bones. Phylogenetic analysis placed the animal at the base of the sauropodomorph family tree. “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,” said You Hailu of the Institute of Vertebrate Paleontology and Paleoanthropology.
Radiometric dating and biostratigraphy dated the layers to about 200 million years ago. Compared with other East Asian sauropodomorphs, Wudingloong had a slender scapula, a higher radius-to-humerus ratio, longer fingers and smoother tooth enamel, features that led the authors to propose a diet of softer vegetation.
Forelimb and pelvic anatomy suggested the dinosaur was bipedal, an inference supported by limb-element proportions and a lightweight pectoral girdle. Although the embryos are too fragmentary to reveal stance, their presence inside rigid shells confirmed that Wudingloong laid hard-shelled eggs.
The five clutches rank among the oldest hard-shelled dinosaur eggs found in Asia. Microscopic ridges and pore canals on the shells indicated a rigid exterior, supporting evidence that sauropodomorphs adopted complex reproductive strategies early in their evolution. The nests are the first definitively linked to a species near the base of Sauropodomorpha.
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