Mapusaurus

Reconstructed skeletons of an adult and a young Mapusaurus

• Argentina ( South America)

• Mapusaurus roseae

Mapusaurus is a South American genus of theropod dinosaurs ( Theropoda ) from the group of Carcharodontosauridae. Fossil remains have been found in about 100 to 94 million years old rocks from the early Late Cretaceous ( Cenomanian ) in the Argentine province of Neuquen.

The only previously known type ( type species ) is Mapusaurus roseae. Before describing this animal was known as a new species of Giganotosaurus.

• 6.1 Literature
• 6.2 Notes and references

Description

The holotype material ( MCF- PVPH - 108.1, Museo Carmen Funes, Paleontologia de Vertebrados, Plaza Huincul, Neuquén ) consists of the right nasal bone. In addition, twelve types of parameters have been described, based on the remaining bone. Of the known copies can be associated with at least seven security Mapusaurus. Taking all findings together, so the majority of the skeleton is represented. However, some individuals are relatively poorly preserved, so it is not sure if that really belong to Mapusaurus or to another Carnosaurier.

The skull of Mapusaurus rosae appear thinner, but deeper than that of Giganotosaurus. The upper jaw is slightly extended, but Mapusaurus has a thin nose. The Antorbitale fossa is about as great as that of Giganotosaurus and Carcharodontosaurus. It is triangular and about as long as high. As in other theropods, the eye was in the upper part of the orbit. The longest known maxillary part of the individual MCF - PVPH 108,169 and is 620 mm long, of which the dentate part makes up 570 mm. The upper jaw of MCF- PVPH - 108 115 is equipped with a 520 mm long row of teeth without obtaining a bit smaller, but better, and relatively high in proportion to its length. In addition, four ( mostly fragmentary ) lower jaw are known. The most complete copy of which is part of the MCF- PVPH - 108 125, is 440 mm long and 72 mm deep at the thinnest part.

Fossil teeth are also obtained a total of 23 teeth are known. The teeth are similar to those of other Carnosaurier, they have flat cutting edges that are cut with fine teeth. These teeth are similar in size to those of Giganotosaurus and Carcharodontosaurus, however, significantly greater than that of Acrocanthosaurus.

Postkranium

The vertebral arch of Mapusaurus was about as large as that of Giganotosaurus (120 mm long and 60 mm deep) and inclined (as with all ) Carnosauriern at the rear of the top. The Epipophyse is more striking than in Allosaurus and Acrocanthosaurus, but it is less conspicuous than in Sinraptor. It is also different from the rather broad Epipophyse of Giganototsuaurs, tapered and runs above pointed to. The spinous process of the vertebral arch is incomplete, but it seems longer and thinner than the being of Giganotosaurus. These extensions are connected by arc plates with the Epipophyse. In Allosaurus and Acrocanthosaurus such arc plates are not available, instead the distance between the spinous process and Epipophyse is greater.

In addition to the many vertebrae ribs fragments and some complete ribs are known. The ribs differ little from those of Allosaurus, Acrocanthosaurus and Sinraptor. From a copy in MCF- PVPH - 108 106 a large, anterior chest rib is obtained, it has a wide depression in the central part of the rear surface. Due to the shape of ribs and vertebrae is believed that Mapusaurus had a not very wide, but the deep chest. A fragmentary abdominal rib is also known, however, distinguishes these were not significantly different from that of other theropods.

A scapula, a coracoid and possibly a leg are partially preserved. In the latter, it is possible that it is fused abdominal ribs, but this is unlikely due to the symmetry of the bone or the lack of signs of a merger. A relatively complete humerus is also known. The known material is 210 mm long and is relatively robust with a diameter of 51 mm at the thinnest point. The total length of the upper arm bone is estimated to be 300 mm. It is thought that the femur (an estimated total length of 1180 mm ) was about four times as long as the humerus. It is therefore assumed that Mapusaurus had (similar to Acrocanthosaurus, Carnotaurus or Aucasaurus ) rather short arms. In addition to the upper arm bone, a spoke is known, which is relatively massive and round in cross-section as well. Little is known about the hand of Mapusaurus.

Size

The bones come from animals of different ages. The size of the dental ( tooth of the bearing part of the lower jaw bone) of the smallest individual is indicative of a length of 5.5 meters, but the bone of the remaining individuals are significantly greater compared with Gigantosaurus fossils. A fibula bone ( MCF- PVPH - 108 202 ) is 860 millimeters in length even two inches longer than the corresponding bones in Giganotosaurus, and a Pubisschaft exceeds this by 10 % ( MUCPv -CH- 1, about 12.2 to 12.5 meters total length). The individuals MCF- PVPH -145, MCF- PVPH -185 and MCF- PVPH -202 are estimated to be 100-103 % of the size of the holotype Giganotosaurus.

System

Together with Giganotosaurus and Tyrannotitan, with which it is closely related, Mapusaurus is classified by the descriptors in the new subfamily Giganotosaurinae, a taxon within the Carcharodontosauridae. All three genera are from the Late Cretaceous of Argentina and among the largest carnivorous land animals ever. The Carcharodontosauridae is still one of the lesser-known theropod families, there are currently several new, yet unnamed animals studied. The group is characterized by flat teeth with sharp cutting edges, a pneumatic braincase, strongly shaped history bone and cervical vertebrae with two Pleurocoelen ( lateral openings ) in a reactor pit.

In a phylogenetic analysis of the year 2011 Mapusaurus is listed as the sister taxon of Giganotosaurus, within the family Carcharodontosaurinae, which consists of Carcharodontosaurus, Giganotosaurus and Mapusaurus.

In a somewhat recent analysis from the year 2012, Mapusaurus is listed not only as a sister taxon of Giganotosaurus, but also of Carcharodontosaurus and Tyrannotitan.

Fund history

The bones of at least seven, possibly up to nine individuals were excavated from 1997 to 2001 under the direction of Argentine- Canadian Dinosaur Project. The reference ( Cañadón del Gato ) is located about 20 kilometers southwest of Plaza Huincul. It is a bone bed (bone stock), a rock section with large bones wealth. All bones found here belong to a single species, which is a major global rarity of large theropods. Also, this is interpreted as an indication of a herd life of Mapusaurus. Abnormalities in the bone at Mapusaurus specimens are relatively rare, but exist. However, injuries are fairly common, so it is assumed that Mapusaurus led an active and dangerous Lebven.

Geologic counts the reference to Huincul lineup is (a portion of the Río Limay - Group), which is part of the Neuquén Group. The Huincul lineup is rather poor in dinosaur fossils, with most finds are only isolated bones. The Mapusaurus locality is the only known bone stock of the formation. From the Cretaceous of Patagonia, an unusually high diversity of forms of large theropod is known except Mapusaurus there are at least nine other species. From the same rock layer ( Huincul Formation) the remains of the giant sauropod Argentinosaurus come.

In the spring of 2006 Mapusaurus was described by Rodolfo A. and Philip J. Currie Corria scientifically, followed by a media wave followed that made Mapusaurus popular. The word " Mapu " in the genus name comes from the language of the Mapuche, a native people in western Patagonia, and means " from the earth ", thus you can Mapusaurus translated as " Erdreptil ". The epithet " roseae " goes back to the reference in red sandstone, but also honors Rose Letwin, who came up for a large part of the excavation costs.