Mapusaurus (“earth lizard”) was a giant carnosaurian dinosaur from the early Late Cretaceous (Cenomanian stage) of what is now Argentina.
It was similar in size to its close relative Giganotosaurus, with the largest known individuals estimated as about 12.2 metres (40 ft) in length or more and weighing 13.5 tonnes (metric tons). The longest individual for which Coria and Currie (2006) provided a concrete estimate in Table 1 (apendix lll) is the animal to which femur MCF-PVPH-208.203 belonged; this individual is estimated as 10.2 metres (33 ft) long.
Mapusaurus was excavated between 1997 and 2001, by the Argentinian-Canadian Dinosaur Project, from an exposure of the Huincul Formation (Rio Limay Subgroup, Cenomanian) at Cañadón del Gato. It was described and named by paleontologists Rodolfo Coria and Phil Currie in 2006.
The name Mapusaurus is derived from the Mapuche word Mapu, meaning ‘of the Land’ or ‘of the Earth’ and the Greek sauros, meaning ‘lizard’. The type species, Mapusaurus roseae, is named for both the rose-colored rocks, in which the fossils were found and for Rose Letwin, who sponsored the expeditions which recovered these fossils.
The designated holotype for the genus and type species, Mapusaurus roseae, is an isolated right nasal (MCF-PVPH-108.1, Museo Carmen Funes, Paleontología de Vertebrados, Plaza Huincul, Neuquén). Twelve paratypes have been designated, based on additional isolated skeletal elements. Taken together, the many individual elements recovered from the Mapusaurus bone bed represent most of the skeleton.
Cladistic analysis carried out by Coria and Currie definitively showed that Mapusaurus is nested within the clade Carcharodontosauridae. The authors noted that the structure of the femur suggests a closer relationship with Giganotosaurus than either taxon shares with Carcharodontosaurus. They created a new monophyletic taxon based on this relationship, the subfamily Giganotosaurinae, defined as all carcharodontosaurids closer to Giganotosaurus and Mapusaurusthan to Carcharodontosaurus. They tentatively included the genus Tyrannotitan in this new subfamily, pending publication of more detailed descriptions of the known specimens of that form.