Sauropod Dinosaurs first appeared around the begining of the Jurassic, undergoing an extinction event at the end of the Early Jurassic, which has been linked to a period of intense global warming, which only a single lineage, the Eusauropods, survived. All subsequent Sauropod groups diversified from this single lineage. One group of Eusauropods, the Neosauropods, would eventually radiate and become the dominant Sauropods through the Late Jurassic and Cretaceous, but in the Middle Jurassic a variety of non-Neosauropod Eusauropods could still be found, particularly in East Asia.
In a paper published in the journal Scientific Reports on 23 May 2025, Ning Li of the School of Earth Sciences and Resources at the China University of Geosciences, Xiaoqin Zhang of Chuxiong Normal University, Xinxin Ren of the Key Laboratory of Stratigraphy and Paleontology of the Ministry of Natural Resources at the Institute of Geology of the Chinese Academy of Geological Sciences, Daqing Li of the Institute of Vertebrate Paleontology at the Gansu Agricultural University, and Hailu You of the Key Laboratory of Vertebrate Evolution and Human Origins at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, and the College of Earth and Planetary Sciences at the University of the Chinese Academy of Sciences, describe a new species of non-Neosauropod Eusauropod from the Middle Jurassic Xinhe Formation of Gansu Province, China.
The Xinhe Formation is a 120 m thick sequence exposed in the Jinchuan District of Jinchang City, which starts at its bottom with a succession of conglomerates, sandstones, and siltstones, becoming finer further up where it becomes a sequence of interbedded shales and mudstones. It is thought to have been laid down in an ancient lake environment, roughly 166-165 million years ago. the specimen from which the new species is described was found in the lower part of this formation.
The new species is named Jinchuanloong niedu, where 'Jinchuanloong' means 'Jinchuan-dragon', and 'niedu' means 'Nickel-city', in reference to the abundant nickel resources in Jinchang, where the metal is mined extensively. It is described from a single specimen, comprising an almost intact skull, lateromedially compressed on its left side, along with the five anteriormost cervical (neck) vertebrae, and, separately, a section of twenty nine articulated caudal (tail) vertebrae. These were confirmed to be from the same animal by impressions of the pelvic girdle and sacral vertebrae, which connect them to the cervical vertebrae. These caudal vertebrae have not been excavated, but remain in place with a protective fence around them.
A phylogenetic analysis recovered Jinchuanloong niedu as a non-Neosauropod Eusauropod outside the two major non-Neosauropod Eusauropod clades, the Mamenchisauridae and the Tauriasauria, forming a sister taxon to the Tauriasauria plus the Neosauropoda. Li et al. suggest that the status of Jinchuanloong niedu as an apparently separate lineage outside of any of the major clades lends support to the idea that East Asia was a significant centre for Sauropod diversification in the Middle Jurassic.
Li et al. further note that the dentition of Middle Jurassic Sauropods from East Asia, and in particular taxa from western China, is extremely variable, which they take as a sign of niche partitioning (i.e. different species having different diets), which in turn could have driven a high rate of taxonomic diversification.
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