Scientists have identified a colossal new dinosaur species in Thailand, after a local villager stumbled upon its bones. The plant-eating giant, named Nagatitan chaiyaphumensis, measured nearly 90 feet (27 meters) in length and roamed the region approximately 113 million years ago during the Cretaceous Period. It is now recognized as the largest-known dinosaur discovered in Southeast Asia.
Discovery and Excavation
The initial discovery occurred when a villager in Thailand's northeastern Chaiyaphum province noticed bones protruding from the ground. Over several years, researchers meticulously excavated a range of skeletal remains, including vertebrae, ribs, pelvic bones, and leg bones. Notably, a front leg bone (humerus) measured an impressive 5.8 feet (1.78 meters) in length.
Physical Characteristics
Nagatitan belongs to the sauropod lineage, characterized by long necks, lengthy tails, small heads, and four columnar legs. Based on the dimensions of its humerus and femur (hind leg bone), scientists estimate its body mass ranged between 25 and 28 tons. Although its skull and teeth were not recovered, researchers infer its feeding habits from other sauropods. "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," said Thitiwoot Sethapanichsakul, a doctoral student in palaeontology at University College London and lead author of the study published in Scientific Reports.
Ancient Environment
The climate during Nagatitan's time was likely subtropical, featuring forests alongside savanna-like and shrubland habitats. It shared its ecosystem with various other dinosaurs, flying reptiles called pterosaurs, and rivers inhabited by crocodiles and fish, including freshwater sharks. The largest predator in the area was a relative of the giant African meat-eating dinosaur Carcharodontosaurus, estimated at around 26 feet (8 meters) long and weighing about 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.
Predator Avoidance
Predators typically avoided healthy adult sauropods due to the risk of being crushed, instead targeting the old, sick, or vulnerable young. "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," added University College London paleontologist and study co-author Paul Upchurch.
Significance and Naming
While Nagatitan was undeniably huge, it did not reach the colossal scale of some South American sauropods like Argentinosaurus and Patagotitan, which exceeded 100 feet (30 meters) in length. The dinosaur's name references Naga, a serpent-like being prominent in Asian religious traditions and depicted in various Thai temples. Thailand now boasts 14 named dinosaur species. Sethapanichsakul suggests Nagatitan could be considered Southeast Asia's last "titan," as the region later transformed into a shallow sea during the Cretaceous period, preventing further sauropod habitation.
Evolutionary Context
Nagatitan belonged to a subgroup of sauropods characterized by bones with numerous internal air sacs and thin walls, which lightened their skeletons. This group emerged around 140 million years ago, achieved global distribution, and by 90 million years ago became the sole surviving sauropod lineage worldwide, thriving until the dinosaur age concluded 66 million years ago with an asteroid impact. Nagatitan lived during a period of rising atmospheric carbon dioxide levels 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 explained. "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."
