Chasicotherium is an extinct genus of a large notoungulate mammal known originally from a partial skull with mandible discovered in the , in the stream of the same name of the Party of Villarino, Province of Buenos Aires, Argentina. The sediments in which the animal remains were discovered date to 10 to 9 million years (Chasicoan). It is known only from its type species, C. rothi. Its weight was approximately 1 tonne (0.98 long tons; 1.1 short tons), being the largest and most recent member of the family Homalodotheriidae. It was a great herbivore of the Miocene Pampas, closely related with Homalodotherium, with it shares the reduced dental formula and the short premaxilla.