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
Temporal range: Cenomanian-Turonian
~97–93.5 Ma
Mapusaurus
Reconstructed skeletons of an adult and a juvenile (left)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Theropoda
Family: Carcharodontosauridae
Tribe: Giganotosaurini
Genus: Mapusaurus
Coria & Currie 2006
Species
  • M. roseae Coria & Currie 2006 (type)

Description

Mapusaurus Scale
Size of a few specimens compared to a human

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).[1] 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,[1] 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)[1] 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).[1]

Holtz estimated the maximum size of the animal at 12.6 metres (41 ft).[2] This estimate has been cited in Drew Eddy and Julia Clarke (2011),[3] and cited again in a phylogenetic table in a 2014 analysis by Canale et al.[4] Other authors suggested that it measured 12.7 metres (42 ft) long and 7.6 metric tons (8.4 short tons) in weight.[5]

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."[1]

Discovery

Reconstrucción elenco del Cráneo del Mapusaurus roseae
Reconstructed skull

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.[1]

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.[1]

Paleobiology

Mapusaurus Roseae restoration
Restoration

The fossil remains of Mapusaurus were discovered in a bone bed containing at least seven individuals of various growth stages.[4][3] Coria and Currie speculated that this may represent a long term, possibly coincidental accumulation of carcasses (some sort of predator trap) and may provide clues about Mapusaurus behavior.[1] Other known theropod bone beds include the Allosaurus-dominated Cleveland-Lloyd Dinosaur Quarry of Utah, an Albertosaurus bone bed from Alberta and a Daspletosaurus bone bed from Montana.

Mapusaurus bones
Mapusaurus bones with pathologies

Paleontologist Rodolfo Coria, of the Museo Carmen Funes, contrary to his published article, repeated in a press-conference earlier suggestions that this congregation of fossil bones may indicate that Mapusaurus hunted in groups and worked together to take down large prey, such as the immense sauropod Argentinosaurus.[6] If so, this would be the first substantive evidence of gregarious behavior by large theropods other than Tyrannosaurus, although whether they might have hunted in organized packs (as wolves do) or simply attacked in a mob, is unknown. The authors interpreted the depositional environment of the Huincul Formation at the Cañadón del Gato locality as a freshwater paleochannel deposit, "laid down by an ephemeral or seasonal stream in a region with arid or semi-arid climate".[1] This bone bed is especially interesting, in light of the overall scarcity of fossilized bone within the Huincul Formation. An ontogenetic study by Canale et al (2014)[4] found that Mapusaurus displayed heterochrony, an evolutionary condition in which the animals may retain an ancestral characteristic during one stage of their life, but lose it as they develop. In Mapusaurus, the maxillary fenestrae are present in younger individuals, but gradually disappear as they mature.

Classification

Mapusaurus-skull-comparison
Comparison of two Mapusaurus roseae skulls

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 Mapusaurus than 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.[1]

The following cladogram after Novas et al., 2013, shows the placement of Mapusaurus within Carcharodontosauridae.[7]

Allosaurus Allosaurus Revised

Carcharodontosauridae

Neovenator Neovenator

Eocarcharia

Concavenator Concavenator corcovatus by Daniel Vidal 2012

Acrocanthosaurus

Shaochilong Shaochilong

Carcharodontosaurinae

Carcharodontosaurus Carcharodontosaurus

Giganotosaurini

Tyrannotitan

Mapusaurus Mapusaurus Roseae restoration

Giganotosaurus Giganotosaurus BW

Paleoecology

As previously mentioned, the Huincul Formation is thought to represent an arid environment with ephemeral or seasonal streams. The age of this formation is estimated at 97 to 93.5 Mya.[2] The dinosaur record is considered sparse here. Mapusaurus shared its environment with sauropods Argentinosaurus (one of the largest sauropods, if not the largest), and Cathartesaura. Abelisauroid theropods Skorpiovenator and Ilokelesia also lived in the region.[8]

References

  1. ^ a b c d e f g h i j Coria, R. A.; Currie, P. J. (2006). "A new carcharodontosaurid (Dinosauria, Theropoda) from the Upper Cretaceous of Argentina". Geodiversitas. 28 (1): 71–118. ISSN 1280-9659. CiteSeerx10.1.1.624.2450 – via ResearchGate.
  2. ^ a b Holtz, Thomas R., Jr. (2012). Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages (PDF). Genus List.
  3. ^ a b Eddy, Drew R.; Clarke, Julia A. (2011-03-21). "New Information on the Cranial Anatomy of Acrocanthosaurus atokensis and Its Implications for the Phylogeny of Allosauroidea (Dinosauria: Theropoda)". PLOS ONE. 6 (3): e17932. Bibcode:2011PLoSO...617932E. doi:10.1371/journal.pone.0017932. ISSN 1932-6203. PMC 3061882. PMID 21445312.
  4. ^ a b c Canale, Juan Ignacio; Novas, Fernando Emilio; Salgado, Leonardo; Coria, Rodolfo Aníbal (2015-12-01). "Cranial ontogenetic variation in Mapusaurus roseae (Dinosauria: Theropoda) and the probable role of heterochrony in carcharodontosaurid evolution". Paläontologische Zeitschrift. 89 (4): 983–993. doi:10.1007/s12542-014-0251-3. ISSN 0031-0220.
  5. ^ Molina-Pérez & Larramendi 2016. Récords y curiosidades de los dinosaurios Terópodos y otros dinosauromorfos, Larousse. Barcelona, Spain p. 262
  6. ^ "Details Revealed About Huge Dinosaurs". ABC News US. Associated Press. 2006.
  7. ^ Novas, Fernando E. (2013). "Evolution of the carnivorous dinosaurs during the Cretaceous: The evidence from Patagonia". Cretaceous Research. 45: 174–215. doi:10.1016/j.cretres.2013.04.001.
  8. ^ Sánchez, Maria Lidia; Heredia, Susana; Calvo, Jorge O. (2006). "Paleoambientes sedimentarios del Cretácico Superior de la Formación Plottier (Grupo Neuquén), Departamento Confluencia, Neuquén" [Sedimentary paleoenvironments in the Upper Cretaceous Plottier Formation (Neuquen Group), Confluencia, Neuquén]. Revista de la Asociación Geológica Argentina. 61 (1): 3–18 – via ResearchGate.

External links

Allosauroidea

Allosauroidea is a superfamily or clade of theropod dinosaurs which contains four families — the Metriacanthosauridae, Allosauridae, Carcharodontosauridae, and Neovenatoridae. Allosauroids, alongside the family Megalosauroidea, were among the apex predators that were active during the Middle Jurassic to Late Cretaceous periods. Of the fourteen allosauroid taxa, five are known for specimens with relatively complete skulls; the taxa are Allosaurus, Sinraptor, Yangchuanosaurus, Carchardontosaurus, and Acrocanthosaurus. The most famous and best understood allosauroid is the North American genus Allosaurus.

The oldest-known allosauroid, Shidaisaurus jinae, appeared in the early Middle Jurassic (probably Bajocian stage) of China. The last known definitive surviving members of the group died out around 93 million years ago in Asia (Shaochilong) and South America (Mapusaurus), though the megaraptorans may belong to the group as well. Additional, but highly fragmentary, remains probably belonging to carcharodontosaurids have been found from the Late Maastrichtian (70-66 Ma ago) in Brazil. An alternative interpretation is to attribute the remains to abelisaurids, which share the distinct pattern of curved wrinkled enamel found in the Brazilian remains with the carcharodontosaurids. This similarity between abelisaurids and carcharodontosaurids means that a definitive match between the Brazilian fossil and carcharodontosaurids cannot be made.Allosauroids had long, narrow skulls, large orbits, three-fingered hands, and usually had "horns" or ornamental crests on their heads. Although allosauroids vary in size, the group maintains a similar center of mass and hip position on their bodies. Allosauroids also exhibit reptilian-style immune systems, secreting fibrin at injured sites to prevent infections from spreading through the bloodstream. This characteristic has been observed by examining injuries and infections on allosauroid bones. It is possible that allosauroids were social animals, as many remains of allosauroids have been found in close proximity to each other. Allosauroids were likely active predators, and from studying endocasts, probably best responded to odors and loud low-frequency noises.

Argentinosaurus

Argentinosaurus (meaning "Argentine lizard") is a genus of titanosaur sauropod dinosaur first discovered by Guillermo Heredia in Argentina. The generic name refers to the country in which it was discovered. The dinosaur lived on the then-island continent of South America somewhere between 97 and 93.5 million years ago, during the Late Cretaceous Period. It is among the largest known dinosaurs.

Bone bed

A bone bed is any geological stratum or deposit that contains bones of whatever kind. Inevitably, such deposits are sedimentary in nature. Not a formal term, it tends to be used more to describe especially dense collections such as Lagerstätte. It is also applied to brecciated and stalagmitic deposits on the floor of caves, which frequently contain osseous remains.In a more restricted sense, the term is used to describe certain thin layers of bony fragments, which occur in well-defined geological strata. One of the best-known of these is the Ludlow Bone Bed, which is found at the base of the Downton Sandstone in the Upper Ludlow series. At Ludlow (England) itself, two such beds are actually known, separated by about 14 ft (4.3 m). of strata. Although quite thin, the Ludlow Bone Bed can be followed from that town into Gloucestershire, for a distance of 45 miles (72 km). It is almost completely made up of fragments of spines, teeth and scales of ganoid fish. Another well-known bed, formerly known as the Bristol or Lias Bone Bed, exists in the form of several thin layers of micaceous sandstone, with the remains of fish and saurians, which occur in the Rhaetic Black Paper Shales that lie above the Keuper marls, in the south-west of England. It is noteworthy that a similar bone bed has been traced on the same geological horizon in Brunswick, Hanover (Germany), in Franconia and in Tübingen (Germany). A bone bed has also been observed at the base of the Carboniferous limestone series, in certain parts of the south-west of England.Bone beds are also recorded in North America, South America, Mongolia and China. Terrestrial bonebed examples are: the Triassic Metoposaurus bone bed from Portugal, the Mapusaurus bone bed at Cañadón del Gato, in Argentina, the Allosaurus-dominated Cleveland-Lloyd Dinosaur Quarry of Utah, the Dinosaur National Monument on the boundary of Utah and Colorado, an Albertosaurus bone bed from Alberta, a Daspletosaurus bone bed from Montana, the Cenozoic John Day Fossil Beds of Oregon and the Nemegt Basin in the Gobi Desert region of Mongolia. Bentiaba, Angola, is an example of a marine bonebed with numerous mosasaurs and plesiosaurs.

Carcharodontosauridae

Carcharodontosaurids (from the Greek καρχαροδοντόσαυρος, carcharodontósauros: "shark-toothed lizards") were a group of carnivorous theropod dinosaurs. In 1931 Ernst Stromer named Carcharodontosauridae as a family, which, in modern paleontology, indicates a clade within Carnosauria. Carcharodontosaurids included some of the largest land predators ever known: Giganotosaurus, Mapusaurus, Carcharodontosaurus, and Tyrannotitan all rivaled or slightly exceeded Tyrannosaurus in length. A 2015 paper by Christophe Hendrickx and colleagues gives a maximum length estimate of 14 meters (46 feet) for the largest carcharodontosaurids, while the smallest carcharodontosaurids were estimated to have been at least 6 meters (20 feet) long.

Carcharodontosaurinae

Carcharodontosaurinae (from the Greek καρχαροδοντόσαυρος, carcharodontósauros: "jagged-toothed lizards") was group of theropod dinosaurs known from the Aptian to the Cenomanian/Turonian of Africa and South America. The clade was first named in 2007 by Steve Brusatte and Paul Sereno. The subfamily consists of gigantic derived carcharodontosaurids, among the largest theropod dinosaurs known, comparable in size to Tyrannosaurus. Carcharodontosaurinae is defined as the least inclusive clade containing Carcharodontosaurus and Giganotosaurus. Within this subfamily is the tribe Giganotosaurini. This tribe was originally its own subfamily, Giganotosaurinae, which was erected by Rodolfo Coria and Philip J. Currie in 2006. In order to keep this clade within the subfamily Carcharodontosaurinae, Brusatte and Sereno renamed and reranked it as a tribe. Giganotosaurini is defined as all carcharodontosaurines that are closer to Giganotosaurus than to Carcharodontosaurus.

Carcharodontosaurus

Carcharodontosaurus is a genus of carnivorous carcharodontosaurid dinosaurs that existed during the Cenomanian stage of the mid-Cretaceous Period. It is currently known to include two species: C. saharicus and C. iguidensis, which were among the larger theropods, nearly as large as or even larger than Tyrannosaurus, Giganotosaurus and Spinosaurus.

The genus Carcharodontosaurus is named after the shark genus Carcharodon, itself composed of the Greek karchar[os] (κάρχαρος, meaning "jagged" or "sharp") and odōn (ὀδών, "teeth"), and the suffix -saurus ("lizard").

Cenomanian

The Cenomanian is, in the ICS' geological timescale the oldest or earliest age of the Late Cretaceous epoch or the lowest stage of the Upper Cretaceous series. An age is a unit of geochronology: it is a unit of time; the stage is a unit in the stratigraphic column deposited during the corresponding age. Both age and stage bear the same name.

As a unit of geologic time measure, the Cenomanian age spans the time between 100.5 ± 0.9 Ma and 93.9 ± 0.8 Ma (million years ago). In the geologic timescale it is preceded by the Albian and is followed by the Turonian. The Upper Cenomanian starts approximately at 95 M.a.

The Cenomanian is coeval with the Woodbinian of the regional timescale of the Gulf of Mexico and the early part of the Eaglefordian of the regional timescale of the East Coast of the United States.

At the end of the Cenomanian an anoxic event took place, called the Cenomanian-Turonian boundary event or the "Bonarelli Event", that is associated with a minor extinction event for marine species.

Giganotosaurus

Giganotosaurus ( JY-gə-NOH-tə-SOR-əs) is a genus of theropod dinosaur that lived in what is now Argentina, during the early Cenomanian age of the Late Cretaceous period, approximately 98 to 97 million years ago. The holotype specimen was discovered in the Candeleros Formation of Patagonia in 1993, and is almost 70% complete. The animal was named Giganotosaurus carolinii in 1995; the genus name translates as "giant southern lizard" and the specific name honours the discoverer, Rubén D. Carolini. A dentary bone, a tooth and some tracks, discovered before the holotype, were later assigned to this animal. The genus attracted much interest and became part of a scientific debate about the maximum sizes of theropod dinosaurs.

Giganotosaurus was one of the largest known terrestrial carnivores, but the exact size has been hard to determine due to the incompleteness of the remains found so far. Estimates for the most complete specimen range from a length of 12 to 13 m (39 to 43 ft), a skull 1.53 to 1.80 m (5.0 to 5.9 ft) in length, and a weight of 4.2 to 13.8 t (4.6 to 15.2 short tons). The dentary bone that belonged to a supposedly larger individual has been used to extrapolate a length of 13.2 m (43 ft). Some researchers have found the animal to be larger than Tyrannosaurus, which has historically been considered the largest theropod, while others have found them to be roughly equal in size, and the largest size estimates for Giganotosaurus exaggerated. The skull was low, with rugose (rough and wrinkled) nasal bones and a ridge-like crest on the lacrimal bone in front of the eye. The front of the lower jaw was flattened, and had a downwards projecting process (or "chin") at the tip. The teeth were compressed sideways and had serrations. The neck was strong and the pectoral girdle proportionally small.

Part of the family Carcharodontosauridae, Giganotosaurus is one of the most completely known members of the group, which includes other very large theropods, such as the closely related Mapusaurus and Carcharodontosaurus. Giganotosaurus is thought to have been homeothermic (a type of "warm-bloodedness"), with a metabolism between that of a mammal and a reptile, which would have enabled fast growth. It may have been relatively fast moving, with a calculated maximal running speed of 14 metres per second (50 km/h; 31 mph). It would have been capable of closing its jaws quickly, capturing and bringing down prey by delivering powerful bites. The "chin" may have helped in resisting stress when a bite was delivered against prey. Giganotosaurus is thought to have been the apex predator of its ecosystem, and it may have fed on juvenile sauropod dinosaurs.

Gualicho

Gualicho (named in reference to the gualichu) is a genus of theropod dinosaur. The type species is Gualicho shinyae. Gualicho lived in what is now northern Patagonia, on what was then a South American island continent split off from the supercontinent Gondwana. The fossils were found in the Huincul Formation, dating to the late Cenomanian-early Turonian age of the upper Cretaceous Period, around 93 million years ago.

Huincul Formation

The Huincul Formation is a geologic formation of Late Cretaceous (Early Cenomanian to Late Turonian) age of the Neuquén Basin that outcrops in the Mendoza, Río Negro and Neuquén Provinces of northern Patagonia, Argentina. It is the second formation in the Río Limay Subgroup, the oldest subgroup within the Neuquén Group. Formerly that subgroup was treated as a formation, and the Huincul Formation was known as the Huincul Member.

List of South American dinosaurs

This is a list of dinosaurs whose remains have been recovered from South America.

Planet Dinosaur

Planet Dinosaur, is a six-part documentary television series created by Nigel Paterson and Phil Dobree, produced by the BBC, and narrated by John Hurt. It first aired in the United Kingdom in 2011, with VFX studio Jellyfish Pictures as its producer. It is the first major dinosaur-related series for BBC One since Walking with Dinosaurs. There are more than 50 different prehistoric species featured, and they and their environments were created entirely as computer-generated images, for around a third of the production cost that was needed a decade earlier for Walking with Dinosaurs. Much of the series' plot is based on scientific discoveries made since Walking with Dinosaurs. The companion book to Planet Dinosaur was released on 8 September 2011, and the DVD and Blu-ray were released on 24 October 2011.

Shaochilong

Shaochilong (meaning "shark toothed dragon") is a genus of carcharodontosaurid dinosaur from the mid Cretaceous (Turonian stage) Ulansuhai Formation of China (about 92 million years ago). The type species, S. maortuensis, was originally named Chilantaisaurus maortuensis, but was re-described and reclassified in 2009.

Siats

Siats is an extinct genus of large neovenatorid theropod dinosaur known from the Late Cretaceous Cedar Mountain Formation of Utah, US. It contains a single species, Siats meekerorum. S. meekerorum could be the first neovenatorid discovered in North America and the geologically youngest allosauroid yet discovered from the continent. It was initially classified as a megaraptoran, a clade of large theropods with very controversial relationships. This group may be examples of tyrannosauroids, neovenatorid allosauroids, or basal coelurosaurs.

Skorpiovenator

Skorpiovenator ("scorpion hunter") is a genus of abelisaurid theropod dinosaur from the Late Cretaceous (Cenomanian to Turonian) Huincul Formation of Argentina. It is one of the most complete and informative abelisaurids yet known, described from a nearly complete and articulated skeleton.

Taurovenator

Taurovenator is a medium-sized carcharodontosaurid theropod from the late Cretaceous of Argentina. Discovered by Matias Motta in 2005 and formally described in 2016, it is represented by an isolated right postorbital.

Turonian

The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous epoch, or a stage in the Upper Cretaceous series. It spans the time between 93.9 ± 0.8 Ma and 89.8 ± 1 Ma (million years ago). The Turonian is preceded by the Cenomanian stage and underlies the Coniacian stage.At the beginning of the Turonian an anoxic event took place which is called the Cenomanian-Turonian boundary event or the "Bonarelli Event".

Tyrannotitan

Tyrannotitan (meaning "titanic tyrant") is a genus of huge bipedal carnivorous dinosaur of the carcharodontosaurid family from the Aptian stage of the early Cretaceous period, discovered in Argentina. It is closely related to other giant predators like Carcharodontosaurus and especially Giganotosaurus as well as Mapusaurus.

Basal allosauroids
Metriacanthosauridae
Allosauria

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