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New Jurassic dinosaur species identified in Thailand from a single bone
A new study published in Scientific Reports describes the identification of a new species of long-necked dinosaur found in the Phu Kradung Formation in Thailand. The team calls the dinosaur Uragasaurus kalasinensis and says it is the first formally named mamenchisaurid dinosaur from Thailand.
Questions of the mamenchisaurid spread
Mamenchisaurids were long-necked sauropod dinosaurs that dominated parts of East Asia during the Middle to Late Jurassic period. Most previously named mamenchisaurid species have come from China, mostly from Sichuan and Xinjiang, but the group's diversity and range outside China have been unclear. There have been some hints that mamenchisaurids existed in Southeast Asia, but only a few diagnostic fossils have been found, and no Thai species had been formally named.
The study authors write, "Recent discoveries outside China have challenged the traditional view that mamenchisaurids were restricted to East Asia. Fragmentary vertebral remains from the Middle to Upper Jurassic Khlong Min Formation of Krabi Province in southern Thailand represent the earliest evidence of mamenchisaurids in Southeast Asia. Additional cervicodorsal elements from the Upper Jurassic to Lower Cretaceous Phu Kradung Formation of northeastern Thailand have also been interpreted as possible members of the clade.
"Furthermore, the reassessment of the caudal vertebrae previously assigned to Janenschia robusta from the Late Jurassic Tendaguru Formation, Tanzania, led to Wamweracaudia keranjei, demonstrating that the group also occurred in Africa."
A new find emerges in Thailand
Only fragmentary possible mamenchisaurid remains had previously been found in Thailand, but the recent finding yielded a more informative fossil in the form of a well-preserved front dorsal vertebra—a part of the dinosaur's spine. The vertebra has a distinctive Y-shaped arrangement of supporting bony ridges, called laminae, which the researchers say is unique among known mamenchisaurids.
Additionally, CT scans showed numerous small, oddly shaped chambers separated by thin bony septa in the main body of the vertebra. These were consistent with air-sac lightweighting seen in other mamenchisaurids, which enabled them to support their heavy necks.
While other disarticulated sauropod parts were found within a few yards of the vertebra, the team says it cannot confidently confirm that they are from the same species. The fossils were not found articulated, and the included elements showed morphology that could differ from the new species, so the team regards them as "associated sauropod materials" instead.
The team conducted a phylogenetic analysis using a published dataset to determine the evolutionary placement of Uragasaurus kalasinensis. The results placed Uragasaurus as an early-branching member of Mamenchisauridae.
A single bone tells a bigger story
Aside from adding a new mamenchisaurid species, the discovery also helps paleontologists piece together details surrounding the evolutionary history of mamenchisaurids and where they spread across the continent. It also provides more information about the Phu Kradung Formation. There has been some debate about which time periods the formation spans, and the new find helps place the lower part of the formation more firmly in the Upper Jurassic age.
The study authors write, "The discovery of Uragasaurus kalasinensis expands the geographic distribution of Mamenchisauridae into mainland Southeast Asia and provides additional evidence that this clade was widespread across eastern Asia during the Late Jurassic. The presence of closely related taxa in China suggests possible faunal connections across the East Asian landmass during this time."
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Publication details
Apirut Nilpanapan et al, A new mamenchisaurid sauropod from the Lower Phu Kradung Formation, Upper Jurassic of northeastern Thailand, Scientific Reports (2026). DOI: 10.1038/s41598-026-49822-3
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Citation: New Jurassic dinosaur species identified in Thailand from a single bone (2026, July 10) retrieved 11 July 2026 from https://phys.org/news/2026-07-jurassic-dinosaur-species-thailand-bone.html
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