New 27‑tonne sauropod Nagatitan chaiyaphumensis identified as Southeast Asia’s largest dinosaur

The discovery comes from a dig in northeast Thailand reported in the journal *Scientific Reports*. Lead author Thitiwoot Sethapanichsakul, a PhD student at University College London, analyzed fossil bones to estimate size and diet. The team used femur circumference and limb bone scaling methods common in palaeontology to calculate body mass.

Nagatitan chaiyaphumensis weighed approximately 27 tonnes, equivalent to nine adult elephants. Its length reached about 27 metres (89 feet). The first bones were uncovered by local residents around 2014, roughly ten years before the excavation was completed in 2024. Sethapanichsakul noted the dinosaur was a "bulk browser" that ate large amounts of vegetation like conifers and seed ferns, which needed little to no chewing.

This find pushes the upper size limit for dinosaurs in Southeast Asia and shows that massive sauropods persisted in the region until the Cretaceous shallow seas took over. The lineage to which Nagatitan belongs originated about 140 million years ago, became the sole sauropod group worldwide by 90 million years ago, and vanished with the asteroid impact 66 million years ago. Researchers will next examine bone histology to determine growth rates and age at death for this giant.