Thailand's 'Nagatitan' named largest dinosaur ever found in Southeast Asia

A villager named Thanom Luangnan was fishing by a pond in Thailand's Chaiyaphum province when he noticed something unusual jutting from the exposed earth. It was 2016, the dry season had pulled the water back, and what he saw—a massive pelvic bone—would eventually lead scientists to name the largest dinosaur ever discovered in Southeast Asia.

Thitiwoot Sethapanichsakul, now a PhD student in palaeontology at University College London, grew up dreaming of exactly this moment. As a high school student, he told his teachers he would one day name a dinosaur from Thailand. When Luangnan's discovery was reported to the Department of Mineral Resources, Sethapanichsakul was among the researchers who began the painstaking work of excavation. Over several years, the team extracted roughly a dozen bones—two massive upper limbs, several vertebrae, ribs, and most of the pelvis. Then funding dried up in 2020, and the specimens sat on shelves, waiting.

It wasn't until 2024, when Sethapanichsakul and co-author Sita Manitkoon from Mahasarakham University secured a National Geographic grant, that the work resumed. They finished the excavation, studied the bones in detail, and began the process of naming what they had found. The moment Sethapanichsakul first saw the upper front leg bone—the humerus—he knew the scale of what they were dealing with. The bone was taller than he was. "I had to stop and go, 'OK. What have I gotten myself into?'" he recalled.

Using detailed scans and statistical correlations between bone circumference and body mass, the team calculated that the creature weighed between 25 and 28 tonnes—roughly equivalent to six elephants or three Tyrannosaurus rex. From head to tail, it stretched 27 metres. They named it Nagatitan chaiyaphumensis, drawing on the serpent Naga from Southeast Asian mythology and the province where the bones were found. The species lived between 120 and 100 million years ago, during the Cretaceous Period, when the world was warming and sauropods were evolving to ever-greater sizes. With a long neck and columnar legs, Nagatitan would have fed on the highest branches of conifer trees, reaching resources no other dinosaur could access. Size itself became an advantage—larger animals were harder for carnivorous dinosaurs to hunt, creating an evolutionary loop that pushed sauropods toward gigantism.

Nagatitan eclipses the Tangvayosaurus from Laos, which weighed roughly 23 tonnes, making it the largest sauropod ever found in the region. Yet the discovery's significance extends beyond the fossil itself. For decades, European and other international teams came to Thailand to excavate and describe dinosaurs, often naming them after local people but rarely including Thai researchers in the process. Sethapanichsakul and Manitkoon deliberately worked to change that pattern, engaging local communities throughout their research and ensuring Thai scientists led the work. When the Thainosaur Museum in Bangkok opened with a life-sized reconstruction of Nagatitan as its centrepiece, the nameplate was unveiled just last week—a moment Sethapanichsakul described as the cherry on top of a childhood dream realized.

The discovery signals a shift. More young Thai researchers are finishing their degrees in palaeontology, more papers are being published, and the prospect of finding additional dinosaurs in the region feels suddenly real. Sethapanichsakul hopes to see a few more sauropods, a few more dinosaurs, emerge from Thai soil in the coming years. What began as a villager's sharp eyes catching something odd by a pond has become a catalyst for a new generation of palaeontologists working in their own country.