Giganotosaurus
Encyclopedia
Giganotosaurus is a genus
of carcharodontosaurid dinosaur
that lived around 97 million years ago during the early Cenomanian
stage
of the Late Cretaceous
Period. It included some of the largest known
terrestrial carnivore
s, slightly larger than the largest Tyrannosaurus
, but smaller than the largest Spinosaurus
. Its fossils have been found in Argentina
.
hunter who, on 25 July 1993, discovered a skeleton in deposits of Patagonia
(southern Argentina
) in what is now considered the Candeleros Formation
. The discovery was scientifically reported in 1994. The initial description was published by Rodolfo Coria and Leonardo Salgado in the journal Nature
in September 1995. The type species
is Giganotosaurus carolinii. The generic name means "giant southern lizard", derived from the Ancient Greek
gigas/γίγας meaning "giant", notos/νότος meaning "south wind" and -sauros/-σαύρος meaning "lizard". The specific name honours Carolini.
The holotype
specimen's (MUCPv-Ch1) skeleton was about 70% complete and included parts of the skull
, a lower jaw, pelvis
, hindlimbs and most of the backbone. The premaxilla
e, jugal
s, quadratojugal
s, the back of the lower jaws and the forelimbs are missing. Various estimates find that it measured somewhere between 12.2 and 13 m (40 and 42.7 ft) in length, and between 6.5 and 13.3 tons in weight. A second, more fragmentary, specimen (MUCPv-95) has also been identified, found in 1987 by Jorge Calvo. It is only known from the front part of the left dentary which is 8% larger than the equivalent bone from the holotype. This largest Giganotosaurus specimen is estimated to represent an individual with a skull length of 195 cm (6.4 ft), compared to the holotype's estimated at 1.8 m (5.9 ft) skull, making it likely that Giganotosaurus had the largest skull of any known theropod.
Giganotosaurus surpassed Tyrannosaurus
in mass by at least half a ton (the upper size estimate for T. rex is 9.1 t). Additionally several single teeth, discovered from 1987 onwards, have been referred to the species.
, encased in an ossified sphenethmoid, means that it probably had a good sense of smell
. Together with these olfactory bulbs, the brain of Giganotosaurus was 18% longer than that of the related large theropod Carcharodontosaurus
.
The shoulder blade was very short and thick, with sudden kinks in its shaft. The ischium had a paddle-shaped end; the thigh bone, 143 centimetres long in the holotype, had a head that was pointing relatively upwards. The mid dorsal vertebrae carried rather high spines.
Titanosaur
fossils belonging to Andesaurus
and Limaysaurus
have been recovered near the remains of Giganotosaurus, leading to speculation that these carnivores may have preyed on the giant herbivore
s. Fossils of the related carcharodontosaurid Mapusaurus
grouped closely together may indicate pack hunting, a behavior that could possibly extend to Giganotosaurus itself.
Blanco and Mazzetta (2001) estimated that for Giganotosaurus a growing imbalance when increasing its velocity would pose an upper limit of 14 m/s (50.4 km/h; 31.3 mph) to its running speed, after which minimal stability would have been lost.
In 2005 François Therrien e.a. estimated that the bite force of Giganotosaurus was three times less than that of Tyrannosaurus and that the lower jaws were optimised for inflicting slicing wounds; the point of the mandibula was reinforced to this purpose with a "chin" and broadened to handle smaller prey.
, Mapusaurus and Carcharodontosaurus, are members of the carnosaur family Carcharodontosauridae
. Both Giganotosaurus and Mapusaurus have been placed in their own subfamily Giganotosaurinae by Coria and Currie in 2006 as more carcharodontosaurid dinosaurs are found and described, allowing interrelationships to be calculated.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of carcharodontosaurid dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
that lived around 97 million years ago during the early Cenomanian
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...
stage
Faunal stage
In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convention have the same name, and the same boundaries.Rock...
of the Late Cretaceous
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
Period. It included some of the largest known
Dinosaur size
Size has been one of the most interesting aspects of dinosaur science to the general public. This article lists the largest and smallest dinosaurs from various groups, sorted in order of weight and length....
terrestrial carnivore
Carnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...
s, slightly larger than the largest Tyrannosaurus
Tyrannosaurus
Tyrannosaurus meaning "tyrant," and sauros meaning "lizard") is a genus of coelurosaurian theropod dinosaur. The species Tyrannosaurus rex , commonly abbreviated to T. rex, is a fixture in popular culture. It lived throughout what is now western North America, with a much wider range than other...
, but smaller than the largest Spinosaurus
Spinosaurus
Spinosaurus is a genus of theropod dinosaur which lived in what is now North Africa, from the lower Albian to lower Cenomanian stages of the Cretaceous period, about 112 to 97 million years ago. This genus was first known from Egyptian remains discovered in 1912 and described by German...
. Its fossils have been found in Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
.
Discovery and species
The most complete find of Giganotosaurus was made by Rubén Dario Carolini, an amateur fossilFossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
hunter who, on 25 July 1993, discovered a skeleton in deposits of Patagonia
Patagonia
Patagonia is a region located in Argentina and Chile, integrating the southernmost section of the Andes mountains to the southwest towards the Pacific ocean and from the east of the cordillera to the valleys it follows south through Colorado River towards Carmen de Patagones in the Atlantic Ocean...
(southern Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
) in what is now considered the Candeleros Formation
Candeleros Formation
The Candeleros Formation is a geologic formation that outcrops in Río Negro, Neuquén, and Mendoza provinces of Argentina. It is the oldest formation in the Neuquén Group and belongs to the Rio Limay Subgroup...
. The discovery was scientifically reported in 1994. The initial description was published by Rodolfo Coria and Leonardo Salgado in the journal Nature
Nature (journal)
Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...
in September 1995. The type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
is Giganotosaurus carolinii. The generic name means "giant southern lizard", derived from the Ancient Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
gigas/γίγας meaning "giant", notos/νότος meaning "south wind" and -sauros/-σαύρος meaning "lizard". The specific name honours Carolini.
The holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
specimen's (MUCPv-Ch1) skeleton was about 70% complete and included parts of the skull
Skull
The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...
, a lower jaw, pelvis
Pelvis
In human anatomy, the pelvis is the lower part of the trunk, between the abdomen and the lower limbs .The pelvis includes several structures:...
, hindlimbs and most of the backbone. The premaxilla
Premaxilla
The incisive bone is the portion of the maxilla adjacent to the incisors. It is a pair of small cranial bones at the very tip of the jaws of many animals, usually bearing teeth, but not always. They are connected to the maxilla and the nasals....
e, jugal
Jugal
The jugal is a skull bone found in most reptiles, amphibians, and birds. In mammals, the jugal is often called the malar or Zygomatic. It is connected to the quadratojugal and maxilla, as well as other bones, which may vary by species....
s, quadratojugal
Quadratojugal
The quadratojugal is a small jaw bone that is present in most amphibians, reptiles, and birds, but has been lost in mammals. It is connected to the jugal as well as other bones, though these may vary with species....
s, the back of the lower jaws and the forelimbs are missing. Various estimates find that it measured somewhere between 12.2 and 13 m (40 and 42.7 ft) in length, and between 6.5 and 13.3 tons in weight. A second, more fragmentary, specimen (MUCPv-95) has also been identified, found in 1987 by Jorge Calvo. It is only known from the front part of the left dentary which is 8% larger than the equivalent bone from the holotype. This largest Giganotosaurus specimen is estimated to represent an individual with a skull length of 195 cm (6.4 ft), compared to the holotype's estimated at 1.8 m (5.9 ft) skull, making it likely that Giganotosaurus had the largest skull of any known theropod.
Giganotosaurus surpassed Tyrannosaurus
Tyrannosaurus
Tyrannosaurus meaning "tyrant," and sauros meaning "lizard") is a genus of coelurosaurian theropod dinosaur. The species Tyrannosaurus rex , commonly abbreviated to T. rex, is a fixture in popular culture. It lived throughout what is now western North America, with a much wider range than other...
in mass by at least half a ton (the upper size estimate for T. rex is 9.1 t). Additionally several single teeth, discovered from 1987 onwards, have been referred to the species.
Description
The skull of Giganotosaurus, although large, had a slender, elongated build. It showed rugose areas on the edges of the snout top and above the eye opening. The supratemporal openings were overhung by the edges of the skull roof where the jaw muscles of each side directly attached instead of meeting each other at a midline skull crest. The back of the skull as preserved is strongly inclined forwards, bringing the jaw joints far behind the attachment point of the neck.Giganotosaurus carolinii was slightly larger than Tyrannosaurus rex, but had a brain smaller than those of tyrannosaurids, its size estimated at 275 cm³. The teeth of Tyrannosaurus were longer and wider, and more variable in size. The teeth of Giganotosaurus were shorter, less variable and narrower than those of Tyrannosaurus, and were more adapted for slicing flesh. A well-developed olfactory regionOlfactory system
The olfactory system is the sensory system used for olfaction, or the sense of smell. Most mammals and reptiles have two distinct parts to their olfactory system: a main olfactory system and an accessory olfactory system. The main olfactory system detects volatile, airborne substances, while the...
, encased in an ossified sphenethmoid, means that it probably had a good sense of smell
Olfaction
Olfaction is the sense of smell. This sense is mediated by specialized sensory cells of the nasal cavity of vertebrates, and, by analogy, sensory cells of the antennae of invertebrates...
. Together with these olfactory bulbs, the brain of Giganotosaurus was 18% longer than that of the related large theropod Carcharodontosaurus
Carcharodontosaurus
Carcharodontosaurus was a gigantic carnivorous carcharodontosaurid dinosaur that lived around 100 to 93 million years ago, during the late Albian to early Cenomanian stages of the mid-Cretaceous Period...
.
The shoulder blade was very short and thick, with sudden kinks in its shaft. The ischium had a paddle-shaped end; the thigh bone, 143 centimetres long in the holotype, had a head that was pointing relatively upwards. The mid dorsal vertebrae carried rather high spines.
Paleobiology
Titanosaur
Titanosaurs were a diverse group of sauropod dinosaurs, which included Saltasaurus and Isisaurus. It includes some of the heaviest creatures ever to walk the earth, such as Argentinosaurus and Paralititan — which some believe have weighed up to 100 tonnes...
fossils belonging to Andesaurus
Andesaurus
Andesaurus is a genus of basal titanosaurian sauropod dinosaur which existed during the middle of the Cretaceous Period in South America. Like most sauropods, it would have had a small head on the end of a long neck and an equally long tail...
and Limaysaurus
Limaysaurus
Limaysaurus is a herbivorous rebbachisaurid sauropod dinosaur from the Lower Cretaceous of northwestern Patagonia.Limaysaurus includes a single type species, Limaysaurus tessonei, which was originally referred to the genus Rebbachisaurus as Rebbachisaurus tessonei by Jorge Calvo and Leonardo...
have been recovered near the remains of Giganotosaurus, leading to speculation that these carnivores may have preyed on the giant herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
s. Fossils of the related carcharodontosaurid Mapusaurus
Mapusaurus
Mapusaurus was a giant carnosaurian dinosaur from the early Late Cretaceous of what is now Argentina. It was similar in size to its close relative Giganotosaurus, with the largest known individuals estimated as over in length and weighing approximately...
grouped closely together may indicate pack hunting, a behavior that could possibly extend to Giganotosaurus itself.
Blanco and Mazzetta (2001) estimated that for Giganotosaurus a growing imbalance when increasing its velocity would pose an upper limit of 14 m/s (50.4 km/h; 31.3 mph) to its running speed, after which minimal stability would have been lost.
In 2005 François Therrien e.a. estimated that the bite force of Giganotosaurus was three times less than that of Tyrannosaurus and that the lower jaws were optimised for inflicting slicing wounds; the point of the mandibula was reinforced to this purpose with a "chin" and broadened to handle smaller prey.
Classification
Giganotosaurus, along with relatives like TyrannotitanTyrannotitan
Tyrannotitan 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 Giganotosaurus and Carcharodontosaurus...
, Mapusaurus and Carcharodontosaurus, are members of the carnosaur family Carcharodontosauridae
Carcharodontosauridae
Carcharodontosaurids were a group of carnivorous theropod dinosaurs. In 1931 Ernst Stromer named Carcharodontosauridae as a family, in modern paleontology this name indicates a clade within Carnosauria...
. Both Giganotosaurus and Mapusaurus have been placed in their own subfamily Giganotosaurinae by Coria and Currie in 2006 as more carcharodontosaurid dinosaurs are found and described, allowing interrelationships to be calculated.
External links
- Giganotosaurus at DinoData.
- "What were the longest/heaviest predatory dinosaurs?" Mike Taylor. The Dinosaur FAQ. August 27, 2002.