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''Regisaurus'' ("Rex's lizard", named after its discoverer Francis Rex Parrington) is an extinct
It was a rather derived
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
of small carnivorous therocephalia
Therocephalia is an extinct suborder of eutheriodont therapsids (mammals and their close relatives) from the Permian and Triassic. The therocephalians ("beast-heads") are named after their large skulls, which, along with the structure of their ...
n. It is known from a single described species, the type species
In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specime ...
''Regisaurus jacobi'', from the Early Triassic
The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between Ma and Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which is a un ...
Lystrosaurus Assemblage Zone
The ''Lystrosaurus'' Assemblage Zone is a tetrapod assemblage zone or biozone which correlates to the upper Adelaide and lower Tarkastad Subgroups of the Beaufort Group, a fossiliferous and geologically important geological Group of the Karoo Su ...
of South Africa
South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. It is bounded to the south by of coastline that stretch along the Atlantic Ocean, South Atlantic and Indian Oceans; to the ...
, although at least one undescribed species is also known.
Description
It was a rather derived baurioid
Baurioidea is a superfamily of therocephalian therapsids. It includes advanced therocephalians such as ''Regisaurus'' and ''Bauria''. The superfamily was named by South African paleontologist Robert Broom in 1911. Bauriamorpha, named by D. M. S. ...
, with a robust skull, short tail, long limbs and relatively large canines
Canine may refer to:
Zoology and anatomy
* a dog-like Canid animal in the subfamily Caninae
** ''Canis'', a genus including dogs, wolves, coyotes, and jackals
** Dog, the domestic dog
* Canine tooth, in mammalian oral anatomy
People with the surn ...
. It was apparently related to ''Urumchia
''Urumchia'' is an extinct genus of therocephalian therapsids from the Early Triassic of China. The type species ''Urumchia lii'' was described by Chinese paleontologist C. C. Young (Yang Zhongjian) in 1952 from the Jiucaiyuan Formation in Xinji ...
'' and like ''Urumchia'', it had vomer
The vomer (; lat, vomer, lit=ploughshare) is one of the unpaired facial bones of the skull. It is located in the midsagittal line, and articulates with the sphenoid, the ethmoid, the left and right palatine bones, and the left and right max ...
bones, which form the secondary palate, but they do not narrow to a tip like in ''Urumchia''. However, it retained some primitive characteristics. It had six incisor
Incisors (from Latin ''incidere'', "to cut") are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight (two on each side, top and bottom). Opossums have 18, wher ...
teeth in each side of the jaw, whereas other baurioids had less. It was probably carnivorous, and ate insects and small vertebrates
Discovery and species
''Regisaurus'' was discovered in 1964 by Francis Rex Parrington and it was named in 1972 by C. H. Mendrez. Two species are known, thetype species
In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specime ...
''Regisaurus jacobi'' and an additional undescribed species
In taxonomy, an undescribed taxon is a taxon (for example, a species) that has been discovered, but not yet formally described and named. The various Nomenclature Codes specify the requirements for a new taxon to be validly described and named. U ...
. ''R. jacobi'' is known from the holotype FRP 1964/27 and the referred specimen BP/1/3973, while the undescribed species is known only from the Holotype T837.
Classification
Below is acladogram
A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...
modified from Sidor (2001) and Huttenlocker (2009):
See also
*List of therapsids
This list of therapsids is an attempt to create a comprehensive listing of all genera that have ever been included in the Therapsida excluding mammals and purely vernacular terms. The list includes all commonly accepted genera, but also genera tha ...
References