In 2016, during the dry season in northeastern Thailand, water levels in a communal pond in Chaiyaphum province receded enough to expose the bank. A local resident noticed a pile of large bones. The bones were unusually large, and the resident reported the find. Paleontologists were notified. Excavations began.
The fieldwork across multiple seasons between 2016 and 2019, and additional work as recently as 2024, recovered vertebrae, ribs, pelvic bones, and leg bones. The recovered fossils then required cleaning, stabilization, analysis, and comparison against the wider sauropod literature.
A decade after the initial sighting, a peer-reviewed paper published in Nature Scientific Reports on May 14, 2026, confirmed the remains as a new species of long-necked dinosaur. The species is Nagatitan chaiyaphumensis, the largest dinosaur ever discovered in Southeast Asia.
The Fossil Was Measured at 27 Meters
The dinosaur was a sauropod, the broad family of long-necked, long-tailed, plant-eating dinosaurs. The published analysis places the animal at approximately 27 meters in length, roughly 89 feet, and approximately 27 metric tons in weight, equivalent to about nine adult Asian elephants. A single front leg bone, the humerus, measured 1.78 meters in length.
The lead researcher, Thitiwoot Sethapanichsakul, a paleontologist at University College London whose doctoral research focuses on Southeast Asian sauropod taxonomy and evolution, noted that when he first saw the humerus, it was taller than he was.
The species belongs to a subgroup of sauropods called Euhelopodidae, a family of long-necked dinosaurs found only in Asia. The structural feature distinguishing Nagatitan from other family members involves a specific combination of features in its spine, pelvis, and legs. The team identified these features by comparing the recovered bones against the wider sauropod literature and closely related species previously identified in Asia.
The skull and teeth were not among the recovered material. Researchers have inferred the animal’s feeding preferences from wider knowledge of sauropod biology rather than from direct evidence of dentition. The right femur, though recovered in several pieces, would have measured about 2 meters in length when intact.
The Name Embeds Mythology and Place
The name does specific cultural work beyond standard zoological convention. The first element, “Naga,” refers to a mythological aquatic serpent appearing in Thai and wider Southeast Asian folklore. The Naga is a powerful and ancient being associated with water, rivers, and lakes, grounding the dinosaur in the cultural context of where it was found.
The second element, “Titan,” refers to the giants of Greek mythology, primordial beings whose scale exceeded that of the later divine order. The element emphasizes the animal’s exceptional size relative to other dinosaurs known from the region.
The species name “chaiyaphumensis” means “from Chaiyaphum,” honoring the Thai province where the fossils were discovered. The research team included Thai paleontologists working alongside researchers from University College London, Mahasarakham University, Suranaree University of Technology, and the Sirindhorn Museum in Thailand. The full taxonomic description and evolutionary analysis appear in the Nature Scientific Reports paper.
The Geological Context Gave It a Nickname
The fossil was recovered from the Khok Kruat Formation, the youngest dinosaur-bearing rock formation in Thailand. The formation dates to the late Early Cretaceous, approximately 100 to 120 million years ago. This geological context earned the dinosaur its informal nickname, “the last titan.”
The rocks laid down in the region after this period are not, on the available evidence, going to contain large dinosaur remains. The geological history of Southeast Asia in the later Cretaceous involves the region becoming a shallow sea. Terrestrial habitats that would have supported animals like Nagatitan gave way to marine environments. Dinosaurs that lived in the region in the later Cretaceous would have left their remains in environments that have not, in most cases, been preserved the same way as the earlier terrestrial deposits.
Sethapanichsakul explicitly characterized the dinosaur in these terms. Younger rocks laid down toward the end of the time of the dinosaurs are unlikely to contain dinosaur remains because the region by then had become a shallow sea. During the Cretaceous, northeastern Thailand would have been a semi-arid environment, and the dinosaur would have used its long body and large surface area to shed heat.
The fossil site was likely part of a river system, and the animal would have lived alongside crocodiles, fish, and fish-eating pterosaurs.
The Regional Record Stands Clear
Nagatitan is exceptional by regional comparison. It is the largest dinosaur fossil discovery in Thailand and larger than any species identified in neighboring countries. Sethapanichsakul noted that Nagatitan likely weighed at least 10 tonnes more than Dippy the Diplodocus, the iconic sauropod whose cast skeleton has been a fixture in major natural history museums.
By global comparison, the animal is not in the same weight class as the largest sauropods ever discovered. The South American sauropod Patagotitan weighed approximately 60 metric tons, more than twice the weight of Nagatitan. Ruyangosaurus, another large Asian sauropod, weighed approximately 50 metric tons.
Argentinosaurus, by some estimates, may have weighed more than 70 metric tons. The exceptional feature of Nagatitan remains its regional dominance as the largest dinosaur ever found in Southeast Asia.
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