Mapusaurus
| Mapusaurus | ||||||||||||
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Reconstructed skeletons of an adult and a young Mapusaurus |
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| Temporal occurrence | ||||||||||||
| Upper Cretaceous ( Cenomanium ) | ||||||||||||
| 100.5 to 93.9 million years | ||||||||||||
| Locations | ||||||||||||
| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Mapusaurus | ||||||||||||
| Coria & Currie , 2006 | ||||||||||||
| Art | ||||||||||||
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Mapusaurus is a South American genus of theropod dinosaurs (Theropoda) from the group of Carcharodontosauridae . Fossil remains were found in rocks from the early Upper Cretaceous ( Cenomanium ) in the Argentine province of Neuquén ,around 100 to 94 million years old.
The only known species ( type species ) is Mapusaurus roseae . Prior to the description, this animal was known as a new species of Giganotosaurus .
description
The holotype material (MCF-PVPH-108.1, Museo Carmen Funes, Paleontología de Vertebrados, Plaza Huincul, Neuquén) consists of the right nasal bone . In addition, twelve paratypes based on the remaining bones have been described. At least seven of the known specimens can be assigned with certainty to Mapusaurus . If you take all the finds together, most of the skeleton is represented. However, some individuals are relatively poorly preserved, which is why it is not certain whether they really belong to Mapusaurus or to another carnosaur.
skull
The skull of Mapusaurus rosae appears thinner but deeper than that of Giganotosaurus . The upper jaw is slightly elongated, but Mapusaurus has a thin nasal bone. The antorbital cranial fossa is about the same size as that of Giganotosaurus and Carcharodontosaurus . It is triangular and about as long as it is tall. As with other theropods, the eye sat in the upper part of the orbit . The longest known upper jaw belongs to the individual MCF-PVPH-108.169 and is 620 mm long, of which the dentate part is 570 mm. The upper jaw of MCF-PVPH-108.115 is somewhat smaller with a 520 mm long row of teeth, but is better preserved and relatively high in relation to its length. In addition, four (mostly fragmentary) lower jaws are known. The most complete of these belongs to specimen MCF-PVPH-108.125, is 440 mm long and 72 mm deep at the thinnest point.
Fossil teeth are also preserved, a total of 23 teeth are known. The teeth are comparable to those of other carnosaurs, so they have flat cutting edges that are sawn with fine teeth. These teeth are comparable in size to those of Giganotosaurus and Carcharodontosaurus , but they are significantly larger than those of Acrocanthosaurus .
Differences in the skull anatomy of individuals suggest heterochrony .
Post cranium
The vertebral arch of Mapusaurus was about as large as that of Giganotosaurus (120 mm long and 60 mm deep) and (as with all carnosaurs) inclined upwards in the rear area. The epipophysis is more conspicuous than in Allosaurus and Acrocanthosaurus , but it is less conspicuous than in Sinraptor . In addition, unlike the rather broad epipophysis of Giganotosaurus , it is conical and tapers at the top. The spinous process of the vertebral arch is incomplete, but it seems to be longer and thinner than that of Giganotosaurus . These processes are connected to the epipophysis by arch plates . In Allosaurus and Acrocanthosaurus there are no such arch plates, instead the distance between the spinous process and epipophysis is greater.
In addition to the vertebrae, many rib fragments and some complete ribs are known. The ribs differ little from those of Allosaurus , Acrocanthosaurus and Sinraptor . From the specimen MCF-PVPH-108.106 a large anterior chest rib has been preserved, this has a wide depression in the middle part of the posterior surface. Due to the shape of the ribs and vertebrae, it is believed that Mapusaurus had a not very wide, but deep chest. A fragmentary abdominal rib is also known, but this does not differ significantly from that of other theropods.
A shoulder blade , a raven bone and possibly a fork bone have survived in part. In the latter, it is possible that they are fused abdominal ribs, but this is unlikely due to the symmetry of the bone or the lack of signs of fusing. 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 length of the owner's entire humerus is estimated to be 300 mm. It is believed that the femur (estimated total length of 1180 mm) was approximately four times as long as the humerus. Therefore, it is believed that Mapusaurus (similar to Acrocanthosaurus , Carnotaurus or Aucasaurus ) had rather short arms. In addition to the humerus, a spoke is also known, which is also relatively massive and round in cross-section. Little is known about the hand of Mapusaurus .
size
The bones come from animals of different ages. The size of the dental (the tooth-bearing part of the lower jaw bone ) of the smallest individual suggests a length of 5.5 meters, but the bones of the other individuals are much larger, comparable to Giganotosaurus fossils. A fibula -Bone (MCF-PVPh-108 202) is 860 millimeters in length even two centimeters longer than the corresponding bone in Giganotosaurus , and a pubis shaft exceeds this 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% the size of the Giganotosaurus holotype, with which the maximum length of Mapusaurus can be estimated at 12.6 m.
Systematics
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 come from the Late Cretaceous Argentina and are among the largest carnivorous land animals at all. The Carcharodontosauridae still belongs to the lesser known theropod families: various new, as yet unnamed animals are currently being investigated. The group is characterized by flat teeth with sharp cutting edges, a pneumatic skull , strongly shaped facial bones and cervical vertebrae with two pleurocoels (lateral openings) in a throttle pit.
In a phylogenetic analysis from 2011, Mapusaurus is listed as a sister taxon of Giganotosaurus within the Carcharodontosaurinae family, which consists of Carcharodontosaurus , Giganotosaurus and Mapusaurus .
In a more recent analysis from 2012, Mapusaurus is listed not only as a sister taxon of Giganotosaurus , but also of Carcharodontosaurus and Tyrannotitan .
Find history
The bones of at least seven, possibly up to nine individuals were excavated from 1997 to 2001 under the direction of an Argentine-Canadian dinosaur project. The site (Cañadón del Gato) is about 20 kilometers southwest of Plaza Huincul . This is a bone bed , a rock section with a large number of bones. All bones found here belong to a single species, which is a great rarity among large theropods worldwide. This is also taken as an indication of a herd life of Mapusaurus . Anomalies in the bones of Mapusaurus specimens are relatively rare, but present. However, injuries are quite common, so it is believed that Mapusaurus led an active and dangerous life.
Geologically, the site belongs to the Huincul Formation (a section of the Río Limay Group), which is part of the Neuquén Group. The Huincul Formation is rather poor in dinosaur fossils, most of the finds are only isolated bones. The Mapusaurus site is the only known bone store of the formation so far. From the Cretaceous Patagonia an extraordinarily high variety of forms of large theropods is known, besides Mapusaurus there are at least nine other species. The remains of the gigantic sauropod Argentinosaurus come from the same rock layer (Huincul Formation) .
In the spring of 2006, Mapusaurus was scientifically described by Rodolfo A. Corria and Philipp J. Currie , which was followed by a wave of media that made Mapusaurus popular. The word "Mapu" in the generic name comes from the language of the Mapuche , an Indian people in western Patagonia , and means "from the earth", so Mapusaurus can be translated as "earth reptile". The specific epithet "roseae" goes back to the site in the red sandstone, but also honors Rose Letwin, who paid for a large part of the excavation costs.
Web links
supporting documents
literature
- Rodolfo A. Coria , Philip J. Currie : A new carcharodontosaurid (Dinosauria, Theropoda) from the Upper Cretaceous of Argentina. In: Geodiversitas. Vol. 28, No. 1, 2006, ISSN 1280-9659 , pp. 71-118, digitized version (PDF, 2.92 MB) .
- Matthew T. Carrano, Roger BJ Benson, Scott D. Sampson: The phylogeny of Tetanurae (Dinosauria: Theropoda). In: Journal of Systematic Palaeontology. Vol. 10, No. 2, 2012, ISSN 1477-2019 , pp. 211-300, doi : 10.1080 / 14772019.2011.630927 .
- Phil R. Bell, Rodolfo A. Coria: Palaeopathological Survey of a Population of Mapusaurus (Theropoda: Carcharodontosauridae) from the Late Cretaceous Huincul Formation, Argentina. In: PLoS ONE . Vol. 8, No. 5, 2013, e63409, doi : 10.1371 / journal.pone.0063409 .
- Drew R. Eddy, Julia A. Clarke: New Information on the Cranial Anatomy of Acrocanthosaurus atokensis and Its Implications for the Phylogeny of Allosauroidea (Dinosauria: Theropoda). In: PLoS ONE. Vol. 6, No. 3, 2011, e17932, doi : 10.1371 / journal.pone.0017932 .
- Juan I. Canale, Fernando E. Novas, Leonardo Salgado, Rodolfo A. Coria: Cranial ontogenetic variation in Mapusaurus roseae (Dinosauria: Theropoda) and the probable role of heterochrony in carcharodontosaurid evolution. In: Paleontological Journal. , 2014, pp. 1-11, doi : 10.1007 / s12542-014-0251-3
Individual evidence
- ^ Coria and Currie 2006, p. 74
- ↑ a b Thomas R. Holtz Jr .: Winter 2011 Appendix. 2012. to: Thomas R. Holtz Jr .: Dinosaurs. The most complete, up-to-date Encyclopedia for Dinosaur Lovers of all Ages. Random House, New York NY 2007, ISBN 978-0-375-82419-7 (PDF; 704 kB).
- ^ Coria and Bell 2013, p. 2
- ↑ a b c d e Coria and Currie 2006, p. 75
- ↑ MT Carrano et al. , P. 234
- ↑ MT Carrano et al. , P. 235
- ^ Coria and Currie 2006, p. 77
- ^ Coria and Currie 2006, p. 78
- ^ Coria and Currie 2006, p. 83
- ↑ a b Coria and Currie 2006, p. 86
- ^ Coria and Currie 2006, p. 117
- ↑ Canale et al. , P. 1
- ^ Coria and Currie 2006, p. 88
- ↑ a b Coria and Currie 2006, p. 95
- ^ Coria and Currie 2006, p. 96
- ↑ a b Coria and Bell 2013, p. 1
- ^ Coria and Currie 2006, p. 109
- ^ Rodolfo A. Coria, Leonardo Salgado : A new giant carnivorous dinosaur from the Cretaceous of Patagonia. In: Nature . Vol. 377, No. 6546, 1995, 225-226, doi : 10.1038 / 377224a0 .
- ↑ Carnosauria
- ↑ Canale et al. , P. 4
- ↑ a b Eddy and Clarke 2011, p. 45
- ^ Coria and Currie 2006, p. 108
- ↑ MT Carrano et al. , P. 248