Tyrannotitan is a genus

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 huge biped

Biped

Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs, or legs. An animal or machine that usually moves in a bipedal manner is known as a biped , meaning "two feet"...

al carnivorous

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...

 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...

 of the carcharodontosaurid

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...

 family from the Aptian

Aptian

The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous epoch or series and encompasses the time from 125.0 ± 1.0 Ma to 112.0 ± 1.0 Ma , approximately...

 stage of the early Cretaceous

Cretaceous

The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...

 period, discovered 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...

. It is closely related to other giant predators like Giganotosaurus

Giganotosaurus

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 carnivores, slightly larger than the largest Tyrannosaurus, but smaller than the...

and 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...

. Its fearsome appearance is reflected in the meaning of its name, "Tyrant titan".

Discovery and species

Tyrannotitan chubutensis was described by Fernando E. Novas, Silvina de Valais, Pat Vickers-Rich, and Tom Rich in 2005. The fossils were found at La Juanita Farm, 28 kilometres (17.4 mi) northeast of Paso de Indios, Chubut Province

Chubut Province

Chubut a province in the southern part of Argentina situated between the 42nd parallel south and the 46th parallel south , the Andes range separating Argentina from Chile, and the Atlantic ocean...

, Argentina. They are believed to have been from the Cerro Castaño Member, Cerro Barcino Formation

Cerro Barcino Formation

The Cerro Barcino Formation is a geological formation in South America whose strata span the mid-late Cretaceous period. Dinosaur remains are among the fossils that have been recovered from the formation....

 (Aptian

Aptian

The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous epoch or series and encompasses the time from 125.0 ± 1.0 Ma to 112.0 ± 1.0 Ma , approximately...

 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...

) around 112.2 - 121 million years ago.

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...

 material was designated MPEF-PV 1156 and included partial dentaries, teeth, back vertebrae 3-8 and 11-14, proximal

Anatomical terms of location

Standard anatomical terms of location are designations employed in science that deal with the anatomy of animals to avoid ambiguities that might otherwise arise. They are not language-specific, and thus require no translation...

 tail vertebrae, ribs and chevrons

Chevron (anatomy)

A chevron is one of a series of bones on the ventral side of the tail in many reptiles, dinosaurs , and some mammals such as kangaroos and manatees....

, a fragmentary scapulocoracoid

Scapulocoracoid

The Scapulocoracoid is the unit of the pectoral girdle that contains the coracoid and scapula.The coracoid itself is a beak-shaped bone that is commonly found in most vertebrates with a few exceptions.The scapula is commonly known as the shoulder blade...

, humerus

Humerus

The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....

, ulna

Ulna

The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form and runs parallel to the radius, which is shorter and smaller. In anatomical position The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form...

, partial ilium

Ilium (bone)

The ilium is the uppermost and largest bone of the pelvis, and appears in most vertebrates including mammals and birds, but not bony fish. All reptiles have an ilium except snakes, although some snake species have a tiny bone which is considered to be an ilium.The name comes from the Latin ,...

, a nearly complete femur

Femur

The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...

, fibula, and left metatarsal 2.

Additional material (designated MPEF-PV 1157) included 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, a right dentary, teeth, atlas vertebra, neck vertebra (?) 9, back vertebrae (?)7, 10, 13, fused sacral centra

Sacrum

In vertebrate anatomy the sacrum is a large, triangular bone at the base of the spine and at the upper and back part of the pelvic cavity, where it is inserted like a wedge between the two hip bones. Its upper part connects with the last lumbar vertebra, and bottom part with the coccyx...

 (5 total), an assortment of distal

Anatomical terms of location

Standard anatomical terms of location are designations employed in science that deal with the anatomy of animals to avoid ambiguities that might otherwise arise. They are not language-specific, and thus require no translation...

 caudals, ribs, the right femur, a fragmentary left metatarsal 2, pedal phalanges 2-1, 2-2, and 3-3.

The length of the animal is estimated to be on average at 12.2 metres (40 ft).

Paleobiology

Little information has yet been released about Tyrannotitan. Only a very brief description of the fossils has been published (four pages). The teeth are less blade-like than those of its kin, and possess odd, lumpy denticles (there is a barely distinguishable groove in the center, dividing each denticle into two parts). Unlike known carcharodontosaurids, this animal lacks pneumaticity extending into the sacral and caudal centra. The scapulocoracoid is fused, and much better developed than that of Giganotosaurus

Giganotosaurus

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 carnivores, slightly larger than the largest Tyrannosaurus, but smaller than the...

carolinii, yet the arm is very small. Most of the shaft of the scapula is missing. The acromion curves about 90 degrees from the shaft axis, making it look vaguely tyrannosaurid

Tyrannosauridae

Tyrannosauridae is a family of coelurosaurian theropod dinosaurs which comprises two subfamilies containing up to six genera, including the eponymous Tyrannosaurus. The exact number of genera is controversial, with some experts recognizing as few as three...

-like. Whether the sharp difference between taxa is due to evolution or sexual dimorphism in poorly-sampled populations of both species, has not been determined (the latter seems unlikely). A proximal caudal has a very tall neural spine (about twice the height of its centrum, judging by the figure). The base of the orbital fenestra is a notch of nearly 90 degrees into the body of the 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....

, which contrasts with the rounded base restored for Giganotosaurus and agrees with 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...

favorably.