Koilamasuchus is an extinct genus of Early Triassic archosauriform. Remains have been found from the Quebrada de los Fósiles Formation of the Puesto Viejo Group in Argentina. The holotype specimen of Koilamasuchus gonzalezdiazi, the type species, is the most well preserved and best known specimen of a basal archosauriform in South America. The fossil has been known since 1981 when it was first described by paleontologist José Bonaparte, but it was not described as a new genus and species until 2010.