Paleontologists have identified a new genus and species of somphospondylan titanosauriform dinosaur — the largest ever found in Southeast Asia — from the fossilized bones found in Thailand, offering fresh evidence that the region was home to a surprisingly diverse group of enormous plant-eaters during the Early Cretaceous.
Stylized life reconstruction of Nagatitan chaiyaphumensis within the arid floodplains of Late Early Cretaceous Aptian-Albian Thailand. Image credit: Patchanop Boonsai.
The newly-described dinosaur species roamed what is now northeastern Thailand around 113 million years ago.
Named Nagatitan chaiyaphumensis, the ancient giant measured 27 m (89 feet) in length and weighed between 25 and 28 tons.
It co-existed with smaller plant-eating dinosaurs such as iguanodontians and early branching ceratopsians, predatory dinosaurs such as carcharodontosaurians and spinosaurids, as well as sharks, turtles, crocodile relatives and pterosaurs.
“Our dinosaur is big by most people’s standards — it likely weighed at least 10 tons more than Dippy the Diplodocus (Diplodocus carnegii),” said lead author Thitiwoot (Perth) Sethapanichsakul, a Ph.D. student at University College London.
“However, it is still dwarfed by sauropods like Patagotitan (60 tons) or Ruyangosaurus (50 tons).”
The fossils of Nagatitan chaiyaphumensis were excavated from the Khok Kruat Formation in Thailand’s Chaiyaphum province.
“We refer to Nagatitan chaiyaphumensis as ‘the last titan’ of Thailand. That is because it was discovered in Thailand’s youngest dinosaur-bearing rock formation,” Sethapanichsakul said.
“Younger rocks laid down towards the end of the time of the dinosaurs are unlikely to contain dinosaur remains because the region by then had become a shallow sea.”
“So this may be the last or most recent large sauropod we will find in Southeast Asia.”
To determine where Nagatitan chaiyaphumensis fit on the sauropod family tree, the paleontologists compared its anatomy with more than 150 other dinosaur species.
Their analysis placed the new species within Euhelopodidae, a group of somphospondylan titanosauriforms known primarily from Asia.
The group includes other well-known species from the region, such as Phuwiangosaurus sirindhornae from Thailand and Tangvayosaurus hoffeti from Laos.
“We suggest it was part of a broader middle Cretaceous body size increase in Asian titanosauriforms, facilitated by rising temperatures and expanded suitable habitat,” the researchers said.
“The discovery of Nagatitan chaiyaphumensis expands the known diversity of Southeast Asian sauropods and improves our understanding of titanosauriform biogeography within the region.”
The team’s paper was published today in the journal Scientific Reports.
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T. Sethapanichsakul et al. 2026. The first sauropod dinosaur from the Lower Cretaceous Khok Kruat Formation of Thailand enriches the diversity of somphospondylan titanosauriforms in southeast Asia. Sci Rep 16, 12467; doi: 10.1038/s41598-026-47482-x
