New Dinosaur Weighing as Much as 9 Elephants Discovered

Paleontology operates on a very particular kind of patience. Years pass, sometimes decades, between the moment a fossil breaks the surface and the moment a scientist can stand before the world and say: this is something new. The bones get cleaned. They get measured, photographed, scanned, compared against hundreds of known species, and argued over in peer-reviewed journals. By the time a new species has a name, the discovery that started everything is often already old news to the people who found it. That gap between the first moment of recognition and the formal announcement is where most of the actual science happens, invisible to everyone outside the lab.

Northeast Thailand has been producing that kind of invisible science for roughly forty years. The region’s red earth has given up the bones of thirteen dinosaur species since its first formally named species was reported in 1986. Most of those discoveries barely registered outside specialist circles. The landscape there, dry and flat and crossed by river systems that have been doing more or less the same thing for a hundred million years, turns out to have been extraordinarily good at preserving the remnants of creatures that no one had any idea still existed beneath it.

The fourteenth named Thai dinosaur is different, and not just because of its size. Nagatitan chaiyaphumensis is the largest dinosaur ever found in Southeast Asia. Its story begins with a local man noticing some strange-looking rocks at the edge of a pond in 2016, and ends, nearly a decade later, with a formal description published in a peer-reviewed journal and a life-size reconstruction currently on display in Bangkok. What happened in between is worth understanding.

Executive Summary

Nagatitan chaiyaphumensis is a member of the sauropod lineage – dinosaurs known for long necks and tails, small heads, and four columnar legs. The herbivore stretched 27 metres (89 feet) and weighed about 27 tonnes. It is likely to have roamed what is now Thailand between 100 and 120 million years ago and is the largest dinosaur ever found in Southeast Asia. The research was led by Thitiwoot Sethapanichsakul, a Thai doctoral student at University College London (UCL), in collaboration with researchers from Mahasarakham University, Suranaree University of Technology, and Thailand’s Sirindhorn Museum. The research was funded by the National Geographic Society.

The Discovery: A Pond, a Villager, and a Decade of Work

The telltale bones were uncovered in 2016 by a local man named Thanom Luangnan in Chaiyaphum Province, northeastern Thailand. According to National Geographic, “initial measurements of the bones excavated suggested that this could be the largest dinosaur ever found in Southeast Asia,” in the words of paleontologist Sita Manitkoon of Mahasarakham University, who led the recovery effort.

NPR reports that the fossils were first discovered by a local resident in 2016 and initial excavation happened between then and 2019, but then funding dried up. When Sethapanichsakul’s team secured new funding, the excavation restarted in 2024. What began as a chance observation at the edge of a drying pond ultimately became a formal multinational research effort spanning nearly a decade.

The Fossil Protection Division and the Regional Office of Mineral Resources found more than 20 fossil pieces at the site. Key fossils included parts of the dorsal vertebrae, sacrum, pelvis, ilium, and pubis, as well as a complete right humerus measuring 178 centimetres – the largest of its kind ever found in Thailand.

Researchers do not have the full skeleton of Nagatitan; they are estimating its size from the spine, rib, pelvis, and leg bones that were discovered. A front leg bone was nearly 6 feet long. Sethapanichsakul described his first encounter with that bone to CNN: when he laid eyes on the humerus, it was taller than he was. He added that the dinosaur is about double the size of another known sauropod species in Thailand.

Anatomy and Classification: What Makes It a New Species

Formally naming a new species requires demonstrating that an animal is genuinely distinct from everything already described. For Nagatitan, that case rested on both unique anatomical features and a comprehensive phylogenetic analysis.

Published in Scientific Reports, the study presents the first diagnostic sauropod specimen from the Khok Kruat Formation, representing a new somphospondylan titanosauriform. Nagatitan is diagnosed by two unique anatomical features and a distinctive character combination, including the presence of two distinct hyposphene-hypantrum morphologies within the middle to posterior dorsal vertebrae. Phylogenetic analyses using a data matrix containing 153 taxa and 570 characters produced well-resolved topologies placing Nagatitan within the somphospondylan clade Euhelopodidae.

In plain terms: the joints between its backbones changed shape in a way that was not seen in previously known relatives. Researchers identified two unique features, plus a distinctive mix of 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.

The researchers found that Nagatitan chaiyaphumensis belongs to a subgroup of sauropods known as Euhelopodidae. These kinds of sauropods are found only in Asia, but their close cousins – the titanosaurs – have been found on every continent, including Antarctica.

Size in Context

Lead author Sethapanichsakul noted that the dinosaur “likely weighed at least 10 tons more than Dippy the Diplodocus (Diplodocus carnegii).” For a generation of visitors to London’s Natural History Museum, Dippy is the yardstick by which all sauropod size is measured – which makes the comparison vivid. That said, Nagatitan was not at the very top of the sauropod size spectrum globally. It is still dwarfed by sauropods like Patagotitan, at 60 tonnes, or Ruyangosaurus, at 50 tonnes. Sethapanichsakul placed the creature in the “upper middle” range of the largest dinosaurs ever discovered.

Scientists dug up spine, rib, pelvis, and leg bones, including the humerus measuring 5.8 feet (1.78 metres) long. Based on the dimensions of its humerus and femur, the researchers estimated Nagatitan‘s body mass at 25 to 28 tons. That range reflects an honest uncertainty built into the methodology: without a complete skeleton, body mass estimates depend on extrapolation from limb bone proportions, a well-established but inherently approximate technique. The study’s authors present this as a range rather than a single figure precisely because the science demands that caution.

Feeding, Behavior, and Daily Life

Head and teeth were not among the fossils recovered, but the research team drew inferences from closely related species. According to Sethapanichsakul, “Nagatitan was probably a bulk browser that focused on consuming high volumes of vegetation that required little to no chewing such as conifers and possibly seed ferns.” The picture is of an animal that moved slowly through its environment, consuming enormous quantities of low-quality plant material, relying on a massive fermentation-based gut rather than complex chewing to extract nutrients.

Nagatitan belonged to a subgroup of sauropods that possessed bones with lots of internal air sacs and thin walls – traits that lightened their skeletons. This skeletal pneumatization (internal air pockets within the bones) is a critical innovation for animals of this size: it allows the skeleton to remain structurally strong while reducing the overall weight that muscles and the cardiovascular system must support. This group originated around 140 million years ago, achieved a global distribution, and around 90 million years ago became the only sauropods left worldwide, thriving until the dinosaur age ended 66 million years ago with an asteroid impact.

Scientists believe the region during the Early Cretaceous was dry to semi-dry, conditions that sauropods appear to have favored. Researchers think the animals may have used their long necks and tails to help release heat and regulate body temperature.

The Ancient Ecosystem: Predators, Climate, and Co-inhabitants

Nagatitan did not share its world with only its own kind. 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.

A Predator-Proof Giant

The ecosystem’s apex carnivore was formidable by any ordinary measure, but it was simply not in the same physical category as its prey. The ecosystem’s largest predator was a relative of the giant African meat-eating dinosaur Carcharodontosaurus, probably about 26 feet long and around 3.5 tons. “At that size, it was dwarfed by Nagatitan. At full size, Nagatitan likely had very little to fear in terms of predation,” Sethapanichsakul said.

Predators probably avoided attacking healthy adults of any large sauropod species because of the danger of being squashed. But they may have targeted old or sick adults or vulnerable babies. UCL paleontologist and study co-author Paul Upchurch elaborated: “Sauropods are known to have grown very quickly after hatching, and this probably relates to the dangers of predation. The sooner sauropods could become large, the safer they were because they would have been more difficult to tackle.” Fast growth from hatchling to near-adult size was, in effect, an anti-predator strategy baked into sauropod biology.

Climate, Carbon Dioxide, and Gigantism

The question of why sauropods grew so extraordinarily large is one paleontology has wrestled with for decades. The Nagatitan discovery adds a data point to an emerging picture. Environmental conditions in Cretaceous Thailand may help explain why Nagatitan was so large. During the time the dinosaur lived, Thailand was closer to the equator than it is today. Clues found in the same formation where Nagatitan was buried indicate that the region was covered by relatively open, slightly dry shrublands.

Nagatitan represents the beginning of a size boom. When researchers looked at other giant sauropods from Asia for comparison, they found that the dinosaurs got even bigger during the warm Cretaceous years following the time of Nagatitan. “Sauropods such as Ruyangosaurus, nearly 60 tons, are among the largest from Asia during the Cretaceous,” Manitkoon noted. They add support to the idea that warm, open, and relatively dry habitats created ideal conditions for sauropods to evolve to giant sizes.

Nagatitan lived at a time when Earth’s atmospheric carbon dioxide levels were climbing, corresponding to high global temperatures. “Sauropods seem to have become particularly large at this time, with gigantic forms living in South America, China, probably North Africa, and now with Nagatitan, a fairly large one in Southeast Asia,” said UCL co-author Paul Upchurch.

The “Last Titan”: Geological Significance

The nickname “the last titan” is not merely rhetorical. It carries precise geological meaning. 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 explained. “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.”

Living in the Early Cretaceous roughly 120 to 100 million years ago, Nagatitan chaiyaphumensis is actually one of the youngest dinosaur species discovered in Thailand. The oldest, another sauropod from Chaiyaphum known as Isanosaurus attavipachi, lived during the Early Jurassic, more than 70 million years earlier. That span – from the very first sauropods in the region to the youngest known formation bearing their remains – is a measure of how completely these animals dominated the prehistoric Thai landmass for an almost incomprehensible stretch of time.

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Naming the Giant: Mythology, Geography, and Meaning

The newly identified species was named Nagatitan chaiyaphumensis. The name combines “Naga,” a legendary serpent from Thai and Southeast Asian mythology, with “Titan,” referencing the giants of Greek mythology. The species name honors Chaiyaphum Province, where the fossils were found.

The Naga connection runs deeper than aesthetics. “The Nagas are also often associated with water, and considering the dinosaur was found on the side of a communal pond, it just seemed very apt to have a serpent giant be the name,” Sethapanichsakul said.

For the lead researcher personally, the stakes were high. Sethapanichsakul described it as fulfilling “a kind of childhood promise.” “That, yeah, I’m going to name a dinosaur one day. And I want it to be from Thailand,” he said.

Thailand’s Growing Paleontological Profile

The significance of this discovery is inseparable from the broader story of Southeast Asian paleontology, which has long operated in the shadow of more heavily publicized discoveries from North America, China, and South America. Northeast Thailand is a hotspot for dinosaur discoveries and has yielded fossils of 13 other species since the first – Siamosaurus suteethorni – was found in 1986. The discovery of Nagatitan chaiyaphumensis marks the region’s, and Thailand’s, 14th unique species.

ScienceDaily reports that Sita Manitkoon, a researcher at the Palaeontological Research and Education Centre at Mahasarakham University, noted: “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. 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 paleontologists who are actively undertaking research and promoting paleontology and its importance within the country.”

The methodology behind the Nagatitan study also reflects how modern international paleontology now functions. Professor Paul Upchurch of UCL noted: “3D scanning and printing have enabled us to study the specimen and collect data without traveling, which reduces the carbon footprint. 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.”

Sethapanichsakul expressed broader ambitions: “My dream is to continue pushing to get Southeast Asian dinosaurs recognized internationally. More international collaborations between Thailand and other institutions like UCL can further our understanding of the region’s paleobiology and apply it to a global context. This all starts with identifying and describing the specimens we have found first. We have a large collection of sauropod fossils that have not yet been formally described – these may include a number of new species.”

That last point deserves emphasis. The Nagatitan announcement may be the headline, but it is also, potentially, just the beginning. Additional large sauropod remains have already been located in another Thai province, and the excavation site in Chaiyaphum remains active.

For anyone wishing to see the creature in full scale, a life-size reconstruction of Nagatitan is currently on display at the Thainosaur Museum at Asiatique in Bangkok.

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What This Finds Means Beyond the Headlines

There is something particular about a discovery like this one. Forty years of paleontology in a country, and you are still finding things that are genuinely unprecedented. The bones of Nagatitan sat under that pond in Chaiyaphum for over 100 million years. They survived the asteroid, the seas that covered the region after the dinosaurs were gone, and every subsequent geological reshuffling before the land gave them back. They were found because a man noticed something odd and thought to tell someone.

What happens next in Thailand is, by the researchers’ own account, still being written. The undescribed sauropod collection at Mahasarakham University may yet contain new species. The excavation at the discovery site is ongoing. For Sethapanichsakul, who has described this find as the fulfillment of a childhood ambition, the naming of Nagatitan is clearly not an ending. The creatures that lived in Cretaceous Thailand are beginning, slowly, to come back into focus – and the picture is turning out to be far larger than anyone expected.

AI Disclaimer: This article was created with the assistance of AI tools and reviewed by a human editor.