Anabisetia
Encyclopedia
Anabisetia is a genus
of ornithopod
dinosaur
from the Late Cretaceous
Period of Patagonia
, South America
. It was a small biped
al herbivore
, almost seven feet (2 m) long.
Argentine
paleontologists Rodolfo Coria
and Jorge Calvo named Anabisetia in 2002. The generic name honors the late Ana Biset, an influential archeologist from Neuquén Province
in Argentina, where the remains of this animal were found. The one named species
is called A. saldiviai, after Roberto Saldivia, a local farmer who discovered the fossil
s in 1993.
There are four specimens known, all listed in the original 2002 description. The holotype
is the most complete of the four. It consists of fragmentary skull
material, including a partial braincase and both dentary
(lower jaw) bones, as well as a complete forelimb from shoulder to hand, a complete hindlimb and foot, and representative vertebrae from all sections of the spinal column. The other three specimens are less complete, but include elements not seen in the holotype, including more vertebrae, a complete pelvis
and a nearly complete, articulated tail. When all four specimens are considered, the skeleton is more or less completely known except for the skull. These specimens are housed at the Museo Carmen Funes
in Plaza Huincul
, Argentina.
All four specimens were discovered at a locality called Cerro Bayo Mesa, south of Plaza Huincul in the Neuquén province of Argentina. This locality is part of the Cerro Lisandro Formation
, which is a geologic formation
within the Rio Limay subgroup of the Neuquén Group
. The sediments in this formation preserve a swamp
which existed from the late Cenomanian
through early Turonian
stages of the Late Cretaceous
Period, or about 95 to 92 million years ago (Leanza et al., 2004).
This dinosaur is thought to be closely related to another Patagonian ornithopod, Gasparinisaura
, although the lack of skull material makes it difficult to place with precision. When originally described, Gasparinisaura and Anabisetia were thought to be basal
iguanodontians, more derived
than Tenontosaurus
. However, more recent cladistic analyses performed by Coria and others indicate that Gasparinisaura actually lies just outside of Iguanodontia, closer to North America
n ornithopods like Thescelosaurus
and Parksosaurus
(Norman et al., 2004). Anabisetia would probably fall in a similar position.
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 ornithopod
Ornithopod
Ornithopods or members of the clade Ornithopoda are a group of ornithischian dinosaurs that started out as small, bipedal running grazers, and grew in size and numbers until they became one of the most successful groups of herbivores in the Cretaceous world, and dominated the North American...
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 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...
, 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 small 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 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...
, almost seven feet (2 m) long.
Argentine
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...
paleontologists Rodolfo Coria
Rodolfo Coria
Dr. Rodolfo Coria is an Argentine paleontologist.He is best known for having directed the field study and co-naming of the Argentinosaurus in 1993, and the Giganotosaurus , in 1996 among other landmark South American dinosaurs...
and Jorge Calvo named Anabisetia in 2002. The generic name honors the late Ana Biset, an influential archeologist from Neuquén Province
Neuquén Province
Neuquén is a province of Argentina, located in the west of the country, at the northern end of Patagonia. It borders Mendoza Province to the north, Rio Negro Province to the southeast, and Chile to the west...
in Argentina, where the remains of this animal were found. The 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...
is called A. saldiviai, after Roberto Saldivia, a local farmer who discovered the fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s in 1993.
There are four specimens known, all listed in the original 2002 description. 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...
is the most complete of the four. It consists of fragmentary 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...
material, including a partial braincase and both dentary
Mandible
The mandible pronunciation or inferior maxillary bone forms the lower jaw and holds the lower teeth in place...
(lower jaw) bones, as well as a complete forelimb from shoulder to hand, a complete hindlimb and foot, and representative vertebrae from all sections of the spinal column. The other three specimens are less complete, but include elements not seen in the holotype, including more vertebrae, a complete 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:...
and a nearly complete, articulated tail. When all four specimens are considered, the skeleton is more or less completely known except for the skull. These specimens are housed at the Museo Carmen Funes
Museo Carmen Funes
Museo Municipal Carmen Funes, or, the Carmen Funes Municipal Museum, is a museum of paleontology in Plaza Huincul, Neuquén Province, Argentina...
in Plaza Huincul
Plaza Huincul
Plaza Huincul is a village and municipality in Neuquén Province in southwestern Argentina.-References:...
, Argentina.
All four specimens were discovered at a locality called Cerro Bayo Mesa, south of Plaza Huincul in the Neuquén province of Argentina. This locality is part of the Cerro Lisandro Formation
Cerro Lisandro Formation
The Lisandro Formation, alternatively known as the Cerro Lisandro Formation, is a geologic formation with outcrops in the Neuquén province of Argentina. It is the youngest formation within the Río Limay Subgroup, the lowest section of the Neuquén Group...
, which 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...
within the Rio Limay subgroup 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...
. The sediments in this formation preserve a swamp
Swamp
A swamp is a wetland with some flooding of large areas of land by shallow bodies of water. A swamp generally has a large number of hammocks, or dry-land protrusions, covered by aquatic vegetation, or vegetation that tolerates periodical inundation. The two main types of swamp are "true" or swamp...
which existed from the late 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...
through early Turonian
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 93.5 ± 0.8 Ma and 89.3 ± 1 Ma...
stages 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, or about 95 to 92 million years ago (Leanza et al., 2004).
This dinosaur is thought to be closely related to another Patagonian ornithopod, Gasparinisaura
Gasparinisaura
Gasparinisaura is a genus of ornithopod dinosaur from the Late Cretaceous. Its fossils were found in Argentina. The type species, Gasparinisaura cincosaltensis, was described in 1996 by Coria and Salgado. Originally classified as an iguanodont, recent research indicates it is more basal...
, although the lack of skull material makes it difficult to place with precision. When originally described, Gasparinisaura and Anabisetia were thought to be 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:...
iguanodontians, more derived
Derived
In phylogenetics, a derived trait is a trait that is present in an organism, but was absent in the last common ancestor of the group being considered. This may also refer to structures that are not present in an organism, but were present in its ancestors, i.e. traits that have undergone secondary...
than Tenontosaurus
Tenontosaurus
Tenontosaurus is a genus of medium- to large-sized ornithopod dinosaur. The genus is known from the late Aptian to Albian ages of the middle Cretaceous period sediments of western North America, dating between 115 to 108 million years ago...
. However, more recent cladistic analyses performed by Coria and others indicate that Gasparinisaura actually lies just outside of Iguanodontia, closer to North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
n ornithopods like Thescelosaurus
Thescelosaurus
Thescelosaurus was a genus of small ornithopod dinosaur that appeared at the very end of the Late Cretaceous period in North America. It was a member of the last dinosaurian fauna before the Cretaceous-Tertiary extinction event around 65.5 million years ago...
and Parksosaurus
Parksosaurus
Parksosaurus was a genus of hypsilophodont ornithopod dinosaur from the early Maastrichtian-age Upper Cretaceous Horseshoe Canyon Formation of Alberta, Canada. It is based on most of a partially articulated skeleton and partial skull, showing it to have been a small, bipedal, herbivorous dinosaur...
(Norman et al., 2004). Anabisetia would probably fall in a similar position.