Nagatitan

Discovery

The fossils of Nagatitan chaiyaphumensis were discovered in 2016 on the edge of a pond in Chaiyaphum Province, Thailand. The bones were discovered because water levels in a communal pond dropped during the dry season, exposing fossils that had previously been hidden beneath the ground.

Excavation was not completed in a single season. Initial work took place between 2016 and 2019, with further excavation continuing in 2024 to recover the remaining fossils.

The known remains include vertebrae, hip bones, and parts of both the front and back limbs. Researchers believe all of the bones belonged to a single individual because no duplicate bones were found, and all the remains were of a consistent size and discovered close together.

The dinosaur's right upper arm bone, or humerus, measured an impressive 1.78 m long - roughly the height of an adult human. One preserved rib was nearly 2 m long, giving an idea of the enormous size of the animal's chest.

Rather than simply guessing its size, scientists calculated its mass using the circumference of the humerus and femur, a widely used method for estimating the weight of large extinct animals.

Anatomy and Classification

Size of Nagatitan compared to a human

The skeleton shows several unusual anatomical features that set Nagatitan apart from other known sauropods. Most strikingly, it possessed wing-like projections on some of its vertebral spines that, according to the authors, have not been reported in any other sauropod.

Its limb bones were also unusual. Compared with those of many other giant sauropods, they were more flattened from side to side, giving them a distinctive oval-shaped cross-section.

Although popular headlines focus on its enormous size, the scientific importance of Nagatitan lies in this unique combination of anatomical features. Together, they allow scientists to confidently recognise it as a new and separate species, making it the first sauropod from the Khok Kruat Formation that can be confidently identified as its own distinct species.

Analysis of its anatomy suggests that Nagatitan belonged to the Euhelopodidae, a family of large long-necked dinosaurs that appears to have been especially successful in Asia during the Early Cretaceous. To investigate its relationships, scientists compared its anatomy with that of many other sauropods and used computer analyses to reconstruct its evolutionary family tree. Although the exact results varied slightly, every analysis placed Nagatitan within the Euhelopodidae.

One of these family trees suggested that Nagatitan was closely related to the European dinosaur Europatitan. If correct, this would mean that a family of dinosaurs previously thought to be confined to Asia - known as euhelopodids - also had close relatives in Europe. However, another analysis did not support this relationship, meaning its closest relatives remain uncertain.

In another version of the family tree, Nagatitan was found to be more closely related to other Southeast Asian sauropods, lying evolutionarily between Tangvayosaurus of Laos and Phuwiangosaurus of Thailand.

Scientists caution that its exact place on the dinosaur family tree may change in future studies, because several other Southeast Asian sauropods remain incompletely described and their relationships are still being worked out.

Environment & Importance

Nagatitan lived in what is now Thailand during the later part of the Early Cretaceous. Its fossils come from the Khok Kruat Formation, a rock unit that preserves evidence of a warm environment that was probably much drier and more open than the lush prehistoric landscapes often imagined. Geological evidence suggests a semi-arid landscape with river systems flowing through a mixture of woodland, shrubland, and savannah-like habitats.

Although no skull or teeth have yet been found, researchers can infer its likely diet from related sauropods. Nagatitan was probably a bulk browser, feeding on large amounts of vegetation that required little chewing, such as conifers and possibly seed ferns.

At the time Nagatitan lived, the region was home to a rich variety of prehistoric life, including large meat-eating dinosaurs, fish-eating spinosaurs, large plant-eating dinosaurs (iguanodonts), early horned dinosaurs, crocodile relatives, turtles, fish, and flying pterosaurs.

The discovery provides further evidence that Southeast Asia was home to very large sauropods, despite the region historically producing fewer giant dinosaur fossils than areas such as China, North America, and South America. Because the Khok Kruat Formation is the youngest dinosaur-bearing rock formation currently known in Thailand, and the region was later covered by shallow seas, researchers suggest that Nagatitan may represent one of the last giant sauropods to have lived in Southeast Asia.

Because only part of the skeleton is currently known, future discoveries may reveal more about its appearance, biology, and exact place in the sauropod family tree.

The fossils were digitally scanned in three dimensions, allowing researchers in different countries to study detailed virtual models without needing to transport the original bones.

The discovery site has since been developed as a dinosaur learning centre, helping to preserve the locality and educate visitors about Thailand's prehistoric heritage. A life-sized reconstruction of Nagatitan has been created and is displayed in Bangkok, giving visitors a chance to appreciate just how enormous this dinosaur would have been in life.