A giant prehistoric rodent weighing about 30 kilograms roamed what is now southern Thailand between 33 million and 35 million years ago, scientists have said after identifying a new species from two fossilised teeth.
The animal, among the largest rodents known from the Paleogene period, was found in the Krabi basin by an international team involving researchers from Thailand, France and Canada.
Its remains were recovered in 2004 from a coal mine in Krabi province. One tooth was discovered by Pannipa Tian, a geologist with Thailand’s Department of Mineral Resources, who initially mistook the unusually large incisor for a bone.
“At first, I thought it was a bone. I showed it to my supervisor, who told me it was a giant rat’s tooth,” Ms Tian, 51, said.
The cream-coloured incisor was visible against the dark coal deposits, while another member of the expedition found a dark-coloured molar on the same day. The team did not have enough evidence or technology at the time to identify the animal.
Detailed analysis carried out more than two decades later established the species as Yakamys sirindhornae. It was named in honour of Thailand’s Princess Sirindhorn, who supports scientific and palaeontological research.
The rodent belonged to the extinct Ischyromyidae family, one of the earliest major groups of rodents. Although its estimated weight was about half that of a large capybara, the world’s biggest living rodent, researchers said its discovery offered fresh clues about how early rodents evolved to reach enormous sizes.
Ms Tian said the find highlighted the diversity of ancient life and suggested that early rodents may have evolved in what is now Thailand before spreading elsewhere. However, with only two teeth recovered, scientists cannot yet determine the animal’s appearance, diet or behaviour.
Even larger prehistoric rodents have been identified elsewhere, including a human-sized species from the Amazon rainforest and fossil evidence of a one-tonne rodent from South America.
