The long-necked giants of Asia were not confined to China as once believed

Nature · Published 3 October 2026 Swipe more like this →

In short: Mamenchisauridae, a group of long-necked sauropod dinosaurs, were long thought to be exclusive to East Asia. Recent discoveries in Thailand and Tanzania are rewriting this narrative, revealing that these massive herbivores roamed far beyond their traditional strongholds, challenging our understanding of their geographic range and evolutionary history.

Mamenchisauridae represents a clade of non-neosauropodan eusauropod dinosaurs that thrived during the Middle to Late Jurassic. They are defined by their exceptionally elongated cervical vertebrae, which possess highly developed pneumatic structures. In more derived members of the group, these features include procoelous anterior caudal vertebrae, a trait that distinguishes them from other eusauropods. While these anatomical characteristics appear in some Cretaceous neosauropod lineages, such as Titanosauria, their presence in mamenchisaurids has historically complicated efforts to map their precise phylogenetic position.

For decades, the fossil record of these dinosaurs was heavily concentrated in China, particularly within the Sichuan Basin's Shaximiao Formation. Famous taxa like Mamenchisaurus constructus and Omeisaurus maoianus became the standard references for the group. However, recent findings have shattered the assumption that mamenchisaurids were limited to East Asian territories. The discovery of Uragasaurus kalasinensis in the Phu Kradung Formation of northeastern Thailand marks the first formally named mamenchisaurid from that region, confirming their presence in Southeast Asia.

The geographic expansion of the clade extends even further. Reassessment of fossils previously assigned to other groups has identified Wamweracaudia keranjei in the Late Jurassic Tendaguru Formation of Tanzania, proving that mamenchisaurids also inhabited Africa. In Thailand, the Phu Kradung Formation—which spans the latest Jurassic and potentially the earliest Cretaceous—suggests these dinosaurs survived into the transition between these two geological periods. These discoveries are vital for understanding the faunal succession and the broader evolutionary trajectory of sauropods, as researchers continue to refine the dating of these formations through stratigraphic and zircon analysis.

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