Along a meandering river in a warm and arid region that is now Thailand roughly 113 million years ago, a plant-eating behemoth almost 27m long browsed on the treetops without much fear of predators due to its sheer size. This was Nagatitan chaiyaphumensis, the largest-known dinosaur from Southeast Asia.
Researchers have unearthed skeletal remains of Nagatitan, a member of the dinosaur lineage called sauropods known for having a long neck, long tail, small head and four columnar legs.
The fossils of this Cretaceous Period dinosaur were first spotted by a villager in Thailand’s northeastern province of Chaiyaphum. Scientists over a period of years then dug up spine, rib, pelvis and leg bones including a front leg bone – the humerus – measuring 1.78m long.
Based on the dimensions of its humerus and femur, the corresponding hind leg bone, the researchers estimated Nagatitan’s body mass at 25 to 28 tons. Its head and teeth were not among the fossils recovered, but the researchers have a good idea of its feeding preferences based on other sauropods.
“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,” said Thitiwoot Sethapanichsakul, a University College London doctoral student in palaeontology and lead author of the research published on Thursday in the journal Scientific Reports.
The climate was probably subtropical, with some forests, but also savanna-like and shrubland habitats. Nagatitan lived alongside various other dinosaurs as well as flying reptiles called pterosaurs. The rivers were teeming with crocodiles and fish including freshwater sharks.
The ecosystem’s largest predator was a relative of the giant African meat-eating dinosaur Carcharodontosaurus, probably about 8m 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.
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