Mapusaurus

Mapusaurus ('Earth lizard') was a giant carnosaurian, Carcharodontosaurid dinosaur from the early Late Cretaceous (late Cenomanian to early Turonian stage) of what is now Argentina and possibly Chile. Mapusaurus was a large theropod and was roughly similar in size to its close relative Giganotosaurus, with the largest known individuals estimated as about 10.2 metres (33 ft) in length or more and weighing about 3 metric tons (3.3 short 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. 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 metres (40 ft) in length, although not with the same exact proportions, having taller and wider neural spines, a more elongate fibula (86 centimetres (34 in) compared to 83.5 centimetres (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 centimetres (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 nassals). 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 millimetres (51 in) long femur with a 455 millimetres (17.9 in) circumference (MCF-PVPH-208.234). Holtz estimated the maximum size of the animal at 12.6 metres (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. Other authors suggested that it measured 12.7 metres (42 ft) long and 7.6 metric tons (8.4 short tons) in weight. Coria and Currie diagnosed Mapusaurus as follows: 'Mapusaurus n. gen. is a carcharodontosaurid theropod whose skull differs from Giganotosaurus in having thick, rugose unfused nasals that are narrower anterior to the nasal/maxilla/lacrimal junction; larger extension of the antorbital fossa onto maxilla; smaller maxillary fenestra; wider bar (interfenestral strut) between antorbital and maxillary fenestrae; lower, flatter lacrimal horn; transversely wider prefrontal in relation to lacrimal width; ventrolaterally curving lateral margin of the palpebral; shallow interdental plates; higher position of Meckelian canal; more posteriorly sloping anteroventral margin of dentary. Mapusaurus roseae is unique in that the upper quadratojugal process of jugal splits into two prongs; small anterior mylohyoid foramen positioned above dentary contact with splenial; second and third metacarpals fused; humerus with broad distal end and little separation between condyles; the brevis fossa of the ilium extends deeply into excavation dorsal to ischial peduncle. It also differs from Giganotosaurus in having conical, slightly curving cervical epipophyses that taper distally; axial posterior zygapohyses joined on midline; smaller and less elaborate prespinal lamina on midline of cervicals; remarkably sharp dorsal margin of cervical neural spines; tall, wider neural spines; curved ischiatic shaft; more slender fibula.' 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.