The ‘Last Titan’ Of Thailand: Scientists Discover New Dinosaur Species

A local resident walking along a drying pond in northeastern Thailand during the 2016 dry season noticed something odd eroding out of the embankment. What looked like ordinary rock turned out to be bone, ancient bone, belonging to what researchers now describe as the largest known sauropod from Southeast Asia. Nearly a decade later, scientists have formally named the creature: Nagatitan chaiyaphumensis, a plant-eating dinosaur that roamed this part of the world roughly 100 million to 113 million years ago and weighed an estimated 25 to 28 tons, about the same as four African elephants.

Published in Scientific Reports, the discovery is the first diagnostic sauropod specimen from Thailand’s Khok Kruat Formation, complete enough to identify as a new species, and it belongs to a group of four-legged, long-necked giants that includes the largest land animals in Earth’s history.

For years, the Khok Kruat Formation had given researchers almost nothing in the way of large plant-eating dinosaur remains. A handful of isolated teeth and bone fragments too broken to classify. Nagatitan changes that entirely, opening a window into a prehistoric corner of Asia that had been largely blank on the dinosaur map.

A Giant Unearthed From a Thai Pond

Excavations at the Chaiyaphum Province site ran from 2016 through 2019, with a final round completed in early 2024. From a single layer of reddish-brown rock, researchers recovered several vertebrae, ribs, pelvic bones, a right upper arm bone roughly 1.78 meters long (about as tall as an average adult), and a mostly complete right thigh bone. No bones were duplicated, all were similar in size, and they were found closely grouped, leading scientists to conclude every piece came from one animal. Those specimens now reside at the Sirindhorn Museum in Kalasin Province, Thailand. Nagatitan is now the 14th dinosaur formally named in Thailand.

Other fossils from nearby layers at the same locality, including teeth from a meat-eating dinosaur, a long-snouted predator, and a freshwater shark, painted a picture of a semi-arid river landscape that still supported a busy mix of animals during the late Early Cretaceous period.

New Species Has Bone Features Found Nowhere Else

Formally naming a new species requires proof that an animal is genuinely distinct from everything already known. Researchers identified two unique features, plus a distinctive mix of 11 anatomical traits, that set Nagatitan apart from known relatives.

One involves the joints between its backbones. Depending on where in the spine a particular bony projection appeared, its shape changed dramatically: triangular in the middle of the back, and narrowing into a vertical ridge closer to the hips. That kind of variation within the same spine had not been documented quite this way in any related animal.

Another standout was a pair of triangular, wing-like bony extensions projecting from the tops of certain backbones. Researchers write that “the presence of anterior aliform processes has not been observed in any other sauropod,” making this a feature entirely unique to Nagatitan.

Also notable: the upper arm bone had an unusually flat, oval cross-section and one distinctively rounded corner. Taken together with the spinal features, those details gave researchers confidence to formally declare a new genus and species.

Its name carries cultural meaning. Naga refers to the mythological serpent-like creature found throughout Asian cultures, particularly in northeastern Thailand, where it is associated with water and Buddhism. Titan comes from Greek mythology, meaning giant. The species name, chaiyaphumensis, honors Chaiyaphum Province, where the bones were found.

Where This New Dinosaur Fits on the Family Tree

To work out where Nagatitan belongs among its relatives, the research team ran a family-tree analysis using 153 dinosaur species and 570 physical traits. Results placed the animal within a family of giant Asian dinosaurs that also includes two other Southeast Asian species: Phuwiangosaurus, from an older Thai rock layer, and Tangvayosaurus, from neighboring Laos.

Some scientists had previously wondered whether those two formed their own tight regional branch within the family. Nagatitan does not appear closely related to either in a way that would support that idea, and a range of physical differences separates all three animals.

Researchers suggest Nagatitan may have been part of a broader trend of body size increase among its wider family group during the middle part of the Cretaceous period, possibly driven by rising temperatures and expanded habitat. They frame this as a hypothesis rather than a firm conclusion.

Lead author Thitiwoot Sethapanichsakul puts it plainly: “We refer to Nagatitan as ‘the last titan’ of Thailand. That is because it was discovered in Thailand’s youngest dinosaur-bearing rock formation. 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.”

Southeast Asia’s fossil record is far less explored than those of North America or China. For a region that size, major finds are still out there, sometimes eroding quietly out of a community pond, waiting for someone to notice.

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