A recently identified species belonging to the sauropod dinosaur genus Mamenchisaurus has been unearthed in China, with fossil evidence pointing to its existence during the Late Jurassic epoch.
A life reconstruction of a distinct Mamenchisaurus species, denoted as Mamenchisaurus sinocanadorum. Image courtesy of Júlia d’Oliveira.
The dinosaur, identified as Mamenchisaurus sanjiangensis, inhabited Earth during the Early Oxfordian stage of the Jurassic period, approximately 160 million years past.
This particular dinosaur represents a divergent member of the mamenchisaurid family, demonstrating a close phylogenetic link to the majority of other Mamenchisaurus species.
Dr. Hui Dai, a paleontologist affiliated with the Chongqing Institute of Paleontology and the Chongqing Key Laboratory of Paleontology and Paleoenvironment Co-evolution, along with his research associates, stated, “The Late Jurassic period witnessed an apex in sauropod dinosaur diversity, characterized by numerous geographically widespread non-neosauropodan eusauropod lineages (such as mamenchisaurids and turiasaurians), and principally by an extensive array of near-globally distributed members of neosauropodan clades (Diplodocoidea and Macronaria).”
“The sedimentary strata from China dating to the Late Jurassic period yield abundant sauropod fossil records, predominantly featuring mamenchisaurids, although definitive neosauropodan specimens are widely documented from the early Middle Jurassic.”
“The prevailing composition of Asian sauropod faunas exhibits a significant divergence from that observed in contemporaneous formations across Europe, North America, and South America.”
“Furthermore, a substantial portion of the Late Jurassic Asian sauropod diversity is derived from deposits attributed to the lower stratigraphic sections, particularly those located near the transition between the Middle and Late Jurassic periods.”
The fragmentary skeleton of Mamenchisaurus sanjiangensis was exhumed from a fossiliferous site situated in Chongqing, Southwest China.
“The fossilized remains were discovered within purplish-red silty mudstone layers situated in the mid-section of the Upper Shaximiao Formation,” the paleontological team reported.
“Historically, this formation has been assigned a general Callovian-Oxfordian age, yet the precise temporal placement of this formation remains a subject of ongoing debate.”
The unveiling of Mamenchisaurus sanjiangensis contributes to the known diversity of early evolving sauropod dinosaurs and furnishes additional insights crucial for comprehending the evolutionary trajectory of sauropods in northwestern China.
The researchers emphasized, “A more precise comprehension of the evolutionary interconnections among Middle-Late Jurassic Chinese eusauropods is essential for validating hypotheses pertaining to the geographical isolation of East Asia from western Laurasia and Gondwana during this era, as well as for reconstructing the broader paleobiogeographical history of early-branching sauropods and eusauropods.”
“Nevertheless, our current understanding of this evolutionary phase is considerably incomplete, necessitating a re-evaluation of specimens from East Asian lineages to bridge existing informational ‘gaps’.”
The research endeavor was officially published on November 25, 2025, within the esteemed journal Scientific Reports.
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H. Dai et al. A novel mamenchisaurid sauropod dinosaur unearthed from the Upper Jurassic of Southwest China offers new evolutionary evidence from East Asian eusauropods. Sci Rep, disseminated online on November 25, 2025; doi: 10.1038/s41598-025-29995-z
