Abelisaurus
Encyclopedia
Abelisaurus is a genus
of abelisaurid theropod dinosaur
from the Late Cretaceous
Period (Campanian
) of what is now South America
. It was a biped
al carnivore
that probably reached 7 to 9 meters (25 to 30 feet) in length, although it is known from only one partial skull
.
The generic name recognizes Roberto Abel as the discoverer of the specimen and former director of the provincial Museum of Cipolletti
in Argentina
, where the specimen is housed. It also incorporates the Greek
σαυρος/sauros, meaning 'lizard'. There is one named species
, A. comahuensis, which honors the Comahue
region of Argentina, where the fossil was found. Both genus and species were named and described by Argentine paleontologists Jose Bonaparte
and Fernando Novas
in 1985, who placed it in the newly-created family
Abelisauridae.
Many other abelisaurids have since been discovered, including extremely complete specimens of Aucasaurus
, Carnotaurus
and Majungasaurus
. Some scientists place Abelisaurus as a basal
abelisaurid, outside the subfamily Carnotaurinae
. Others are less certain of its position. Abelisaurids share some skull features with the unrelated carcharodontosaurids
and, since Abelisaurus is known only from a skull, future discoveries may show that this genus was in fact a carcharodontosaurid. However, this is thought unlikely.
skull of Abelisaurus is incomplete, especially on the right side. It is also missing most of the palate
(roof of the mouth). Despite the missing pieces, it is over 85 centimeters (33 inches) long. Although there are no bony crests or horns, like those found in some other abelisaurids, such as Carnotaurus, rough ridges on the snout and above the eyes might have supported some kind of crest made out of keratin
, which would not have become fossilized. There are also very large fenestrae (window-like openings) in the skull, which are found in many dinosaurs and reduce skull weight.
Abelisaurus is one of the many dinosaurs that have been discovered in Patagonia
. It was originally described as coming from the Allen Formation
but subsequent research proved the remains were actually found in the older Anacleto Formation
(part of the Neuquén Group
) of Rio Negro Province
, Argentina. The Anacleto is a geologic formation
in South America, dating from the early Campanian
stage of the Late Cretaceous
Period, between 83 and 80 million years ago.
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 abelisaurid theropod 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...
from the Late 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 (Campanian
Campanian
The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch . The Campanian spans the time from 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma ...
) of what is now South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
. It was a 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 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...
that probably reached 7 to 9 meters (25 to 30 feet) in length, although it is known from only one partial 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...
.
The generic name recognizes Roberto Abel as the discoverer of the specimen and former director of the provincial Museum of Cipolletti
Cipolletti
Cipolletti is a city in north of the Patagonian , with 75,078 inhabitants as of the .The city is located on the north-eastern shore of the Neuquén River, just before it is joined by the Limay River to form the Negro River, a short distance upstream from the city of General Roca...
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...
, where the specimen is housed. It also incorporates the 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...
σαυρος/sauros, meaning 'lizard'. There is one named species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, A. comahuensis, which honors the Comahue
Comahue
.Comahue is a sub-region of Argentina slightly to the south of the country's centre that covers the northern part of Argentine Patagonia and includes the provinces of Neuquén and Río Negro....
region of Argentina, where the fossil was found. Both genus and species were named and described by Argentine paleontologists Jose Bonaparte
José Bonaparte
José Fernando Bonaparte, Ph.D. , is an Argentine paleontologist who discovered a plethora of South American dinosaurs and mentored a new generation of Argentine paleontologists like Rodolfo Coria...
and Fernando Novas
Fernando Novas
Fernando Emilio Novas is an Argentine paleontologist working for the Comparative Anatomy Department of the Bernardino Rivadavia Natural History Argentine Museum in Buenos Aires...
in 1985, who placed it in the newly-created family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Abelisauridae.
Classification
Aucasaurus
Aucasaurus was a genus of medium-sized theropod dinosaur from Argentina that lived during the Santonian stage . It was smaller than the related Carnotaurus, although more derived in some ways, such as its extremely reduced arms and almost total lack of fingers.The type skeleton is complete to the...
, Carnotaurus
Carnotaurus
Carnotaurus was a large predatory dinosaur. Only one species, Carnotaurus sastrei has been described so far.Carnotaurus lived in Patagonia, Argentina during the Campanian or Maastrichtian stage of the Late Cretaceous...
and Majungasaurus
Majungasaurus
Majungasaurus is a genus of abelisaurid theropod dinosaur that lived in Madagascar from 70 to 65.5 million years ago, at the end of the Cretaceous Period. Only one species has been identified...
. Some scientists place Abelisaurus as a basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
abelisaurid, outside the subfamily Carnotaurinae
Abelisauridae
Abelisauridae is a family of ceratosaurian theropod dinosaurs. Abelisaurids thrived during the Cretaceous Period, on the ancient southern supercontinent of Gondwana, and today their fossil remains are found on the modern continents of Africa and South America, as well as on the Indian...
. Others are less certain of its position. Abelisaurids share some skull features with the unrelated carcharodontosaurids
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...
and, since Abelisaurus is known only from a skull, future discoveries may show that this genus was in fact a carcharodontosaurid. However, this is thought unlikely.
Fossil material and age
The one known fossilFossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
skull of Abelisaurus is incomplete, especially on the right side. It is also missing most of the palate
Palate
The palate is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but, in most other tetrapods, the oral and nasal cavities are not truly separate. The palate is divided into two parts, the anterior...
(roof of the mouth). Despite the missing pieces, it is over 85 centimeters (33 inches) long. Although there are no bony crests or horns, like those found in some other abelisaurids, such as Carnotaurus, rough ridges on the snout and above the eyes might have supported some kind of crest made out of keratin
Keratin
Keratin refers to a family of fibrous structural proteins. Keratin is the key of structural material making up the outer layer of human skin. It is also the key structural component of hair and nails...
, which would not have become fossilized. There are also very large fenestrae (window-like openings) in the skull, which are found in many dinosaurs and reduce skull weight.
Abelisaurus is one of the many dinosaurs that have been discovered in 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...
. It was originally described as coming from the Allen Formation
Allen Formation
The Allen Formation is a geological formation in Argentina whose strata date back to the Late Cretaceous The Allen Formation is a geological formation in Argentina whose strata date back to the Late Cretaceous The Allen Formation is a geological formation in Argentina whose strata date back to the...
but subsequent research proved the remains were actually found in the older Anacleto Formation
Anacleto Formation
The Anacleto Formation is a geologic formation with outcroppings in the Argentine Patagonian provinces of Mendoza, Río Negro, and Neuquén. It is the youngest formation within the Neuquén Group and belongs to the Río Colorado Subgroup...
(part of the Neuquén Group
Neuquén Group
The Neuquén Group is a group of geologic formations found in Argentina. Rocks in the Neuquén Group fall within the Cenomanian to early Campanian stages of the Late Cretaceous Period, about 100 million to 80 million years in age...
) of Rio Negro Province
Río Negro Province
Río Negro is a province of Argentina, located at the northern edge of Patagonia. Neighboring provinces are from the south clockwise Chubut, Neuquén, Mendoza, La Pampa and Buenos Aires. To the east lies the Atlantic Ocean.Its capital is Viedma...
, Argentina. The Anacleto is a geologic formation
Geologic formation
A formation or geological formation is the fundamental unit of lithostratigraphy. A formation consists of a certain number of rock strata that have a comparable lithology, facies or other similar properties...
in South America, dating from the early Campanian
Campanian
The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch . The Campanian spans the time from 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma ...
stage 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, between 83 and 80 million years ago.
External links
- Abelisaurus in the Dino Directory
- Abelisaurus at DinoData