Summary The climate was probably subtropical, with some forests, but also savanna-like and shrubland habitats.
(Web Desk) - Researchers discover skeletal remains of Nagatitan, the largest-known dinosaur from Southeast Asia.
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 5.8 feet (1.78 metres) 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 26 feet (8 metres) 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.
"Indeed, 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," University College London palaeontologist and study co-author Paul Upchurch said.
Sauropods included the largest land animals in Earth's history. Nagatitan was huge by any standard, but not on the scale of some South American sauropods such as Argentinosaurus and Patagotitan that topped 100 feet (30 metres) long.
