10 years ago, a group of dinosaur hunters discovered a pile of giant bones at the edge of a pond in north-eastern Thailand. These bones have since been studied by researchers from University College London (UCL), Mahasarakham University, Suranaree University of Technology, and Sirindhorn Museum in Thailand and identified as a new species of sauropod dinosaur.
The dinosaur has been named Nagatitan chaiyaphumensis after Chaiyaphum, the province where its remains were found almost a decade ago. This remote part of north-eastern 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 N.chaiyaphumensis marks the region’s, and Thailand’s, 14th unique species.
Amongst the pile of bones were several vertebrae and ribs, parts of the pelvis, and two leg bones - one of which measures 1.78m.
After analysing the bones and determining they belonged to a new species of sauropod, researchers compared them to other, closely related species and estimated N.chaiyaphumensis would have weighed 27 tonnes - roughly the same as nine adult Asian elephants - and measured 27m in length (roughly the same length as a blue whale).
“Our dinosaur is big by most people’s standards - it likely weighed at least 10 tonnes more than ‘Dippy the Diplodocus’ (Diplodocus carnegii)," said lead author Thitiwoot (Perth) Sethapanichsakul, a Thai PhD student in UCL’s Earth Sciences department. "However, it is still dwarfed by sauropods like Patagotitan (60 tonnes) or Ruyangosaurus (50 tonnes)."
N.chaiyaphumensis belongs to a family of dinosaurs known as the sauropods - long-necked, plant-eating dinosaurs that include the likes of Diplodocus, Brontosaurus and Argentinosaurus. These were amongst the largest dinosaurs to ever live. In fact, according to estimates, the largest of them - Argentinosaurus (90 tonnes) - may not only be the largest dinosaur ever, but the largest land animal, period.
Living in the Early Cretaceous roughly 120–100 million years ago, N.chaiyaphumensis is actually one of the youngest species of dinosaur discovered in Thailand. The oldest, another sauropod from Chaiyaphum known as Isanosaurus attavipachi, lived during the Early Jurassic, more than 70 million years earlier.
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“We refer to Nagatitan as ‘the last titan’ of Thailand,” said Sethapanichsakul. “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.”
The environment of north-eastern Thailand was very similar during the Early Cretaceous as it is now, with semi-arid to arid plateaus covering large parts of the region. The site where N.chaiyaphumensis was discovered is believed to have been part of a meandering river system. This site has also yielded remains of fish, freshwater sharks and crocodiles.
Based on other fossils that have been found nearby, it’s thought N.chaiyaphumensis may have lived alongside a handful of iguanodontians and ceratopsians - herbivorous ornithischian dinosaurs - as well as several carcharodontosaurians and spinosaurids. These would have been the apex predators of north-eastern Thailand, though whether they were capable of hunting long-necked giants like N.chaiyaphumensis is unclear.
The researchers found that N.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. The discovery of N.chaiyaphumensis highlights Thailand’s rich dinosaur diversity and may help shine a long-overdue spotlight on the region.
“My dream is to continue pushing to get Southeast Asian dinosaurs recognised internationally,” said Sethapanichsakul. “More international collaborations between Thailand and other institutions like UCL can further our understanding of the region’s palaeobiology 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.”
Find out more about the study, published in the journal Scientific Reports.
Top image: Illustration of N. chaiyaphumensis. Credit: Patchanop Boonsai
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