Pseudhesperosuchus
Encyclopedia
Pseudhesperosuchus is a genus
of sphenosuchia
n, a type of basal
crocodylomorph
, the clade
that comprises the crocodilia
ns and their closest kin. It is known from a partial skeleton and skull found in rocks of the Norian
-age Upper Triassic Los Colorados Formation
, Argentina
.
PVL 3830. This specimen consists of a skull and lower jaws, most of the vertebral column, the shoulder girdle, and parts of the arms and legs. The genus was named by José Bonaparte
in 1969. The type species
is P. jachaleri. The skull, though nearly complete, is poorly preserved, and some of its bones and sutures have been misidentified over the years. A 2002 phylogenetic analysis
of sphenosuchians performed by James Clark and Hans–Dieter Sues found Pseudhesperosuchus to have an unresolved position along with several other sphenosuchians, neither closer to true crocodiles or to Sphenosuchus
. The genus is sometimes misspelled Pseudohesperosuchus, as in Carroll (1988).
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 sphenosuchia
Sphenosuchia
Sphenosuchia is a suborder of basal crocodylomorphs that first appeared in the Triassic and occurred into the Late Jurassic. Most were small, gracile animals with an erect limb posture. They are now thought to be ancestral to crocodyliforms, which include all living crocodilians.-Stratigraphic...
n, a type of 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:...
crocodylomorph
Crocodylomorpha
The Crocodylomorpha are an important group of archosaurs that include the crocodilians and their extinct relatives.During Mesozoic and early Tertiary times the Crocodylomorpha were far more diverse than they are now. Triassic forms were small, lightly built, active terrestrial animals. These were...
, the clade
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
that comprises the crocodilia
Crocodilia
Crocodilia is an order of large reptiles that appeared about 84 million years ago in the late Cretaceous Period . They are the closest living relatives of birds, as the two groups are the only known survivors of the Archosauria...
ns and their closest kin. It is known from a partial skeleton and skull found in rocks of the Norian
Norian
The Norian is a division of the Triassic geological period. It has the rank of an age or stage . The Norian lasted from 216.5 ± 2.0 to 203.6 ± 1.5 million years ago. It was preceded by the Carnian and succeeded by the Rhaetian.-Stratigraphic definitions:The Norian was named after the Noric Alps in...
-age Upper Triassic Los Colorados Formation
Los Colorados Formation
The Los Colorados Formation is a sedimentary rock formation found in La Rioja, Argentina. It has a Norian age , and is notable for its fossils of early dinosaurs, including the coelophysoid Zupaysaurus and the "prosauropods" Coloradisaurus, Lessemsaurus, and Riojasaurus.-Dinosaurs:Indeterminate...
, 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...
.
History and description
Pseudhesperosuchus is based onHolotype
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...
PVL 3830. This specimen consists of a skull and lower jaws, most of the vertebral column, the shoulder girdle, and parts of the arms and legs. The genus was named by José 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...
in 1969. 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 P. jachaleri. The skull, though nearly complete, is poorly preserved, and some of its bones and sutures have been misidentified over the years. A 2002 phylogenetic analysis
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
of sphenosuchians performed by James Clark and Hans–Dieter Sues found Pseudhesperosuchus to have an unresolved position along with several other sphenosuchians, neither closer to true crocodiles or to Sphenosuchus
Sphenosuchus
Sphenosuchus is an extinct genus of sphenosuchian from the Elliot Formation of South Africa, discovered and described early in the 20th century. The skull is excellently preserved but other than elements of the forelimb and isolated parts of the hind limb, the Sphenosuchus material is incomplete...
. The genus is sometimes misspelled Pseudohesperosuchus, as in Carroll (1988).