Massive dinosaur fossil unearthed beneath pond in Thailand 

(CN) — Ten years ago, workers at the edge of a pond in northeastern Thailand uncovered bones belonging to the largest dinosaur ever found in Southeast Asia.

Now, a team of researchers led by University College London has identified the ancient giant, naming it Nagatitan chaiyaphumensis. The name draws on the Naga, a mythological serpent from Thai and Southeast Asian folklore, and on Chaiyaphum, the Thai province where the fossils were found.

Scientists believe the dinosaur lived between 100 and 120 million years ago during the Early Cretaceous period. It was a sauropod, the family of long-necked, long-tailed plant-eaters that includes the Diplodocus and Brontosaurus.

Researchers estimate its weight at 27 tons, roughly equivalent to nine adult Asian elephants, and its length at around 89 feet. Among the bones analyzed was a front leg bone measuring 5.8 feet, about as tall as an average human.

It is the 14th dinosaur named in Thailand.

Lead author Thitiwoot Sethapanichsakul, a Thai doctoral student at UCL Earth Sciences, put the discovery in context.

“Our dinosaur is big by most people’s standards. It likely weighed at least 10 tons more than Dippy the Diplodocus,” Sethapanichsakul said. “However, it is still dwarfed by sauropods like Patagotitan (60 tons) or Ruyangosaurus (50 tons).”

Despite its impressive size, Nagatitan belongs to a subgroup of sauropods called somphospondylans, which spread widely across the globe about 120 million years ago. Within that group, it fits into a smaller cluster called Euhelopodidae, found only in Asia. Researchers say the species stands apart from others based on a unique combination of features on its spine, pelvis and legs.

Sethapanichsakul called it the last titan of Thailand. The fossils came from the country’s youngest dinosaur-bearing rock formation. Layers of rock laid down after that, as the region gradually became a shallow sea, are unlikely to hold any further large sauropod remains.

“This may be the last or most recent large sauropod we will find in Southeast Asia,” he said.

During Nagatitan’s time, the landscape would have been dry and sparse, conditions that sauropods appeared to favor. Scientists think the animals used the large surface area of their long necks and tails to shed heat and keep their body temperatures in check. The area where the bones were found appears to have been part of a winding river system, home to fish, freshwater sharks and crocodiles.

The creature would also have shared the region with smaller plant-eating dinosaurs, large predators and flying reptiles called pterosaurs that hunted fish from the river.

Co-author Professor Paul Upchurch of UCL Earth Sciences said the research grew out of a new partnership with Thai researchers. The team used 3D scanning to study specimens without needing to travel, which he said also helped reduce the project’s carbon footprint.

“We have had a long-standing interest in the evolution of these gigantic plant eaters and have good collaborative links with researchers around the world,” Upchurch said. “It is great to work with Thai colleagues and start to get insights into what was happening in Southeast Asia during the Jurassic and Cretaceous.”

Project leader Sita Manitkoon, a researcher at the Palaeontological Research and Education Centre at Mahasarakham University and a National Geographic Explorer, said Thailand’s fossil record is richer than many people realize.

“Although Thailand is a small country within Asia, we have a very high diversity in dinosaur fossils, possibly the third most abundant in Asia in terms of dinosaur remains,” Manitkoon said. “We’ve only really been studying dinosaurs in Thailand about 40 years, since the first dinosaur was named in 1986, and already we have a surge of younger generation palaeontologists who are actively undertaking research.”

For Sethapanichsakul, the publication is also personal. The research team has a large collection of sauropod fossils not yet formally described, which may include additional new species.

“I’ve always been a dinosaur kid. This study doesn’t just establish a new species but also fulfils a childhood promise of naming a dinosaur,” he said.

A life-size reconstruction of Nagatitan chaiyaphumensis is on display at the Thainosaur Museum at Asiatique in Bangkok.

The findings, titled “‘Last titan’: Southeast Asia’s biggest dinosaur discovered,” were published Thursday in the journal Scientific Reports.

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