A new broad-snouted fossil carettochelyid turtle from a previously unknown Caenozoic deposit in Sarawak, Malaysia

Fossils of pan-carettochelyid turtles are known from most continents of the world, except Antarctica. The fossils that have been described indicate a group of estuarine turtles that have little modified their body form since the Cretaceous. The only species for which ecological data exist is the extant Carettochelys insculpta, found in estuarine or fresh waters in Australia and New Guinea. Here we report the discovery of an incomplete skull of a previously unknown carettochelyid Carettochelys niahensis sp. nov. from an undated fossil deposit within or beneath a Miocene marine limestone formation in Niah Great Cave, Sarawak, Malaysia. The skull exhibits many anatomical features characteristic of this turtle group but differs from previously known taxa in that it has a broad, nasal orifice that is proportionately wider than in other carettochelyids and relatively shallow but wider temporal arches. Some aspects of the palaeoecology of this turtle are inferred.