Scientists from the United Kingdom and Thailand have identified a new species of giant dinosaur from fossils discovered in northeastern Thailand, naming it Nagatitan chaiyaphumensis — the largest dinosaur ever found in Southeast Asia. The creature weighed between 25 and 28 tonnes, roughly equivalent to nine adult Asian elephants, and stretched approximately 27 metres (88 feet) in length, making it longer than a diplodocus and about twice the size of a Tyrannosaurus rex. The findings were published in the journal Scientific Reports.

The fossils were first spotted by a villager beside a pond in Chaiyaphum province, a region in northeastern Thailand, around a decade ago. Researchers subsequently excavated spine, rib, pelvis and leg bones, including a humerus — a front leg bone — measuring 1.78 metres long, which allowed scientists to estimate the animal's mass and dimensions. Though no skull or teeth were recovered, researchers drew on comparisons with related species to conclude that Nagatitan was likely a bulk browser, consuming large volumes of vegetation such as conifers and seed ferns that required little or no chewing.

Nagatitan belonged to the sauropods, a lineage of long-necked, four-legged herbivores that included the largest land animals in Earth's history. It lived approximately 100 to 120 million years ago during the Cretaceous period, in a landscape that was probably warm, partly forested and savanna-like, shared with pterosaurs, crocodiles, freshwater sharks and a large predatory dinosaur related to the African Carcharodontosaurus. Despite this predator, Nagatitan likely had little to fear: at roughly 27 metres, it dwarfed every other creature in its ecosystem, and researchers note that predators generally avoided attacking healthy adult sauropods for fear of being crushed. The name itself blends Southeast Asian and classical traditions — "naga" refers to a serpent-like being in regional religious folklore, prominently depicted in Thai temples, while "titan" evokes the gods of Greek mythology.

The discovery carries broader scientific significance. Lead author Thitiwoot Sethapanichsakul, a Thai doctoral student at University College London, described Nagatitan as possibly "the last titan" of Thailand, because the fossils were found in the country's youngest dinosaur-bearing rock layer — younger deposits were submerged under a shallow sea, meaning future sauropod discoveries there are unlikely. Co-author Professor Paul Upchurch of UCL noted that Nagatitan lived at a time of rising atmospheric carbon dioxide and elevated global temperatures, a period when sauropods across South America, China and North Africa were also growing to enormous sizes. While the link between climate and body size is not yet fully understood, researchers believe high temperatures may have influenced the abundance and type of plant matter available to these vast herbivores. Thailand is now considered one of Asia's most dinosaur-rich countries, with Nagatitan becoming the 14th named species found there.