Mapusaurus

***Mapusaurus*** (meaning "Earth lizard") was a giant carcharodontosaurid carnosaurian dinosaur from the early Late Cretaceous (late Cenomanian to early Turonian stage), approximately 97 to 93 million years ago, of what is now Argentina.

*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.

*Mapusaurus* was a large theropod, and was roughly similar in size to its close relative *Giganotosaurus*, with the largest known individuals estimated as about 11.5 meters (38 ft) to 12.6 meters (41 ft) in length or more and weighing about 3 metric tons (3.3 short tons) to 5 metric tons (5.5 short tons). The longest individual for which Coria and Currie (2006) provided a concrete estimate in Table 1 (appendix lll) is the animal to which femur MCF-PVPH-208.203 belonged; this individual is estimated as 10.2 meters (33 ft) long.

Coria and Currie note the presence of isolated bones from at least one longer individual, but do not provide a figure, instead finding the larger bones coherent with an individual of comparable size to *Giganotosaurus* holotype estimated at 12.2 meters (40 ft) in length, although not with the same exact proportions, having taller and wider neural spines, a more elongate fibula (86 centimeters (34 in) compared to 83.5 centimeters (32.9 in)) but more slender (81–89% the width as in *Giganotosaurus*) as well as a wider pubic shaft in minimal dimensions (10% wider as indicated by a 7.8 centimeters (3.1 in) long fragment catalogued as MCF-PVPH-108.145), and with a differently proportioned skull, shorter in length than *Giganotosaurus* because the maxilla is not elongated (12 teeth compared to 14 in *Carcharodontosaurus*), but deeper in proportion due to this, as well as narrower (due to the narrow nasals). Considering this, a fragmentary maxilla is coherent with the size of the *Giganotosaurus*-sized individual (MCF-PVPH-108.169). A neural arch from an axis (MCF-PVPH-108.83) and a scapular blade fragment are also the same exact size as the same elements in *Giganotosaurus*. The weight estimate of 3,000 kilograms (6,600 lb) is from a 1,300 millimeters (51 in) long femur with a 455 millimeters (17.9 in) circumference (MCF-PVPH-208.234).

Holtz estimated the maximum size of the animal at 12.6 meters (41 ft). This estimate has been cited in Drew Eddy and Julia Clarke (2011), and cited again in a phylogenetic table in a 2014 analysis by Canale *et al.*. Gregory Paul gave a lower estimation of 11.5 meters (37.7 ft) and 5 metric tons (5.5 short tons).

It has been determined that *Mapusaurus* was diagnosed on autapomorphies, or unique traits, in regions of the skeleton that *Giganotosaurus* does not preserve. *Mapusaurus* only differs from *Giganotosaurus* in lacking a second opening on the middle quadrate, and in some details of the topology of the nasal rugosities.