Largest Dinosaur in Southeast Asia Unearthed in Thailand

Paleontologists have unearthed the largest dinosaur fossil ever discovered in Southeast Asia, a plant-eating behemoth named Nagatitan chaiyaphumensis, in Thailand’s northeastern province of Chaiyaphum. The colossal sauropod, estimated to be nearly 90 feet long, lived approximately 113 million years ago during the Cretaceous Period.

The discovery was made serendipitously by a local villager who found skeletal remains. Over several years, scientists meticulously excavated vertebrae, rib fragments, pelvic bones, and leg bones, including a remarkable 5.8-foot-long humerus. Based on the dimensions of its humerus and corresponding femur, researchers estimate Nagatitan weighed between 25 to 28 tons, making it a truly massive creature.

“Nagatitan was probably a bulk browser that focused on consuming high volumes of vegetation that required little to no chewing such as conifers and possibly seed ferns,” explained Thitiwoot Sethapanichsakul, a doctoral student at University College London and lead author of the study published in Scientific Reports. While its head and teeth were not recovered, analysis of related sauropods provides insight into its diet and herbivorous lifestyle.

A Prehistoric Ecosystem Revealed

The environment where Nagatitan roamed was likely a subtropical savanna with scattered forests. This enormous herbivore shared its habitat with other dinosaurs, pterosaurs, and formidable predators. The largest known predator in this ecosystem was a relative of Carcharodontosaurus, measuring about 26 feet long and weighing an estimated 3.5 tons.

“At that size, it was dwarfed by Nagatitan. At full size, Nagatitan likely had very little to fear in terms of predation,” Sethapanichsakul noted. Large adult sauropods, due to their sheer size, were formidable creatures that predators generally avoided. However, younger, older, or sick individuals would have remained vulnerable. Paul Upchurch, a paleontologist at University College London and co-author of the study, added, “Indeed, sauropods are known to have grown very quickly after hatching, and this probably relates to the dangers of predation. The sooner sauropods could become large, the safer they were because they would have been more difficult to tackle.”

Sauropods, the group to which Nagatitan belongs, represent some of the largest land animals in Earth's history. While Nagatitan was immense, it did not reach the colossal scales of South American giants like Argentinosaurus or Patagotitan, which exceeded 100 feet in length.

The name Nagatitan chaiyaphumensis honors the mythical serpent-like Naga from Asian religious traditions and the province of its discovery. This finding is significant as only 14 dinosaur species have been named from Thailand, and Nagatitan is the largest and most geologically recent sauropod identified in the region. Its existence offers valuable insights into the diversity of these giants in Southeast Asia.

Nagatitan belonged to a subgroup of sauropods characterized by lightweight skeletons with numerous internal air sacs. This group, which emerged around 140 million years ago, achieved global distribution and eventually became the only sauropod lineage to survive until the end of the dinosaur age 66 million years ago. The discovery also coincides with a period of rising atmospheric carbon dioxide and high global temperatures.

“Sauropods seem to have become particularly large at this time, with gigantic forms living in South America, China, probably North Africa, and now with Nagatitan a fairly large one in Southeast Asia,” Upchurch commented. “This possible relationship between large body size and high climatic temperatures is not fully understood, but it’s likely that the high temperatures had an impact on the plant fodder that was important to sauropods, which were very large-bodied herbivores. Nagatitan gives a glimpse of the period leading up to the eventual peak in body size and temperatures about 10 to 15 million years later.”