Almasaurus
Encyclopedia
Almasaurus is an extinct genus
of trematosauria
n temnospondyl within the family
Latiscopidae
. It is known from several skulls and some postcranial material found from the Argana Formation
in Morocco
, which dates back to the Early Triassic
.
When it was first named in 1972, Almasaurus was placed within its own superfamily, the Almasauroidea. Although the related latiscopid Latiscopus disjunctus possesses exoccipitals that are underplated (a feature that suggests that it is a member of the family Trematosauridae
) Almasaurus is not considered to be a trematosaurid because it lacks such underplating. Almasaurus was considered to be a capitosauria
n by Warren & Black (1985) because it shared several characters with the group, including a deeply notched squamosal
and a lacrimal
flexure, while supposedly exhibiting none of the characters associated with trematosaurians. However, more recent studies have concluded that Almasaurus is either a temnospondyl more basal than the clade formed from the dichotomy between Capitosauria and Trematosauria or that the genus is closely related to the trematosaurian family Metoposauridae
, perhaps being a sister taxon of it.
A temnospondyl genus described in 2000, Rileymillerus
, is thought to be closely related to Almasaurus.
Below is a cladogram
showing the phylogenetic position of Almasaurus, from Schoch (2008):
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 trematosauria
Trematosauria
Trematosauria is one of two major groups of temnospondyl amphibians that survived the Permian-Triassic extinction event, the other being the Capitosauria. The trematosaurs were a diverse and important group that included many medium-sized to large forms that were semi-aquatic to totally aquatic...
n temnospondyl within the 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...
Latiscopidae
Latiscopidae
Latiscopidae is a family of Temnospondyli....
. It is known from several skulls and some postcranial material found from the Argana Formation
Argana Formation
The Argana Formation is a geological formation in Africa. It dates back to the Late Triassic.-Vertebrate fauna:Ornithischian tracks geographically located in the Province de Marrakech. Indeterminate theropod remains and tracks geographically located in the Province de Marrakech....
in Morocco
Morocco
Morocco , officially the Kingdom of Morocco , is a country located in North Africa. It has a population of more than 32 million and an area of 710,850 km², and also primarily administers the disputed region of the Western Sahara...
, which dates back to the Early Triassic
Early Triassic
The Early Triassic is the first of three epochs of the Triassic period of the geologic timescale. It spans the time between 251 ± 0.4 Ma and 245 ± 1.5 Ma . Rocks from this epoch are collectively known as the Lower Triassic, which is a unit in chronostratigraphy...
.
When it was first named in 1972, Almasaurus was placed within its own superfamily, the Almasauroidea. Although the related latiscopid Latiscopus disjunctus possesses exoccipitals that are underplated (a feature that suggests that it is a member of the family Trematosauridae
Trematosauridae
Trematosauridae are a family of large temnospondyl amphibians with many members. They first appeared during the Olenekian stage of the Early Triassic, and existed up until around the Carnian stage of the Late Triassic, although by then they were very rare...
) Almasaurus is not considered to be a trematosaurid because it lacks such underplating. Almasaurus was considered to be a capitosauria
Capitosauria
Capitosauria is a clade of stereospondyl temnospondyls. Capitosauria and its sister taxon Trematosauria are the only major temnospondyl clades that existed during the Mesozoic....
n by Warren & Black (1985) because it shared several characters with the group, including a deeply notched squamosal
Squamosal
The squamosal is a bone of the head of higher vertebrates. It is the principal component of the cheek region in the skull, lying below the temporal series and otic notch and bounded anteriorly by postorbital. Posteriorly, the squamosal articulates with the posterior elements of the palatal complex,...
and a lacrimal
Lacrimal bone
The lacrimal bone, the smallest and most fragile bone of the face, is situated at the front part of the medial wall of the orbit. It has two surfaces and four borders.-Lateral or orbital surface:...
flexure, while supposedly exhibiting none of the characters associated with trematosaurians. However, more recent studies have concluded that Almasaurus is either a temnospondyl more basal than the clade formed from the dichotomy between Capitosauria and Trematosauria or that the genus is closely related to the trematosaurian family Metoposauridae
Metoposauridae
Metoposauridae is an extinct family of trematosaurian temnospondyls. The family is known from the Triassic and Jurassic periods. Most members are large, approximately long...
, perhaps being a sister taxon of it.
A temnospondyl genus described in 2000, Rileymillerus
Rileymillerus
Rileymillerus is an extinct genus of prehistoric amphibian.-See also:* Prehistoric amphibian* List of prehistoric amphibians...
, is thought to be closely related to Almasaurus.
Below is a cladogram
Cladogram
A cladogram is a diagram used in cladistics which shows ancestral relations between organisms, to represent the evolutionary tree of life. Although traditionally such cladograms were generated largely on the basis of morphological characters, DNA and RNA sequencing data and computational...
showing the phylogenetic position of Almasaurus, from Schoch (2008):
External links
- Almasaurus in the Paleobiology DatabasePaleobiology Database' is an online resource for information on the distribution and classification of fossil animals, plants, and microorganisms.-History:The Paleobiology Database was founded in 2000. It has been funded by the National Science Foundation and the Australian Research Council...