Prehistoric 'giant rat' found in Thailand from fossil teeth
Scientists have identified a new species of giant rodent that lived in Thailand 33 to 35 million years ago based on fossilized teeth. The animal, estimated to weigh 30 kilograms, provides new insights into the evolutionary history of large rodents during the Paleogene period.
Why it matters
This discovery helps paleontologists understand the evolutionary timeline and size diversification of early mammals in Southeast Asia.
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Add to Preferred Sources Lower second molar (m2) of Yakamys sirindhornae gen. et sp. nov. (holotype, TF 2942). (A) Stereopair in occlusal view; (B) mesial view; (C) half-buccal view; (D) buccal view; (E) half-distal view; (F) distal view; (G) half-lingual view; and (H) lingual view. Scale bar = 5 mm. Credit: Scientific Reports (2026). DOI: 10.1038/s41598-026-76711-6 A giant rodent weighing around 30 kilograms (66 pounds) roamed what is now southern Thailand 33 to 35 million years ago, scientists said, after identifying a previously unknown species from two fossilized teeth.
The ancient animal, which one geologist on the team called a "giant rat," was among the largest known from the Paleogene period, offering new clues about how early rodents evolved to enormous sizes.
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