''Steppesaurus'' is an extinct genus of basal
Eupelycosauria
Eupelycosauria is a large clade of animals characterized by the unique shape of their skull, encompassing all mammals and their closest extinct relatives. They first appeared 308million years ago during the Early Pennsylvanian epoch, with the fo ...
belonging to the
Sphenacodontidae
Sphenacodontidae (Greek: "wedge point tooth family") is an extinct family of small to large, advanced, carnivorous, Late Pennsylvanian to middle Permian pelycosaurs. The most recent one, ''Dimetrodon angelensis'', is from the late Kungurian or e ...
, related to ''
Dimetrodon
''Dimetrodon'' ( or ,) meaning "two measures of teeth,” is an extinct genus of non-mammalian synapsid that lived during the Cisuralian (Early Permian), around 295–272 million years ago (Mya). It is a member of the family Sphenacodontid ...
'' and ''
Sphenacodon
''Sphenacodon'' (meaning "wedge point tooth") is an extinct genus of synapsid that lived from about 300 to about 280 million years ago (Ma) during the Late Carboniferous and Early Permian periods. Like the closely related '' Dimetrodon'', ''Sphen ...
'', from the
Late Permian
Late may refer to:
* LATE, an acronym which could stand for:
** Limbic-predominant age-related TDP-43 encephalopathy, a proposed form of dementia
** Local-authority trading enterprise, a New Zealand business law
** Local average treatment effect, ...
San Angelo Formation
The San Angelo Formation is a geologic formation in Texas. It preserves fossils dating back to the Permian period. It is one of the geologically youngest formations to preserve fossils of pelycosaurs.
Stratigraphy and age
The San Angelo Formati ...
of
Texas
Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...
.
Discovery and naming
A maxilla and dentary,
holotype
A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...
FMNH UR 148, were at the
Pease River
The Pease River is a river in Texas, United States. It is a tributary of the Red River that runs in an easterly direction through West Texas . It was discovered and mapped for the first time in 1856 by Jacob de Córdova, who found the river whi ...
found by
Everett Claire Olson in 1950, who named the genus in 1953, together with James R. Beerbower, after J. Steppe who had assisted in the excavation.
Description
The body length of ''Steppesaurus'' has been estimated as high as eighteen feet, making it the largest known sphenacodontid, but this failed to take into account that its teeth, as restored, were more widely spaced. It likely had less teeth in its maxilla, which as a whole was not particularly large.
Classification
Olson in 1953 placed ''Steppesaurus'' in the Sphenacodontidae but in 1962 changed this to the
Phthinosuchidae
''Phthinosuchus'' is an extinct genus of therapsids from the Middle Permian of Russia. ''Phthinosuchus'' is the sole member of the family Phthinosuchidae. ''Phthinosuchus'' may have been one of the most primitive therapsids, meaning that its ance ...
, making it a member of the
Therapsida, as support for his hypothesis that these had been found in the
Early Permian 01 or '01 may refer to:
* The year 2001, or any year ending with 01
* The month of January
* 1 (number)
Music
* '01 (Richard Müller album), 01'' (Richard Müller album), 2001
* 01 (Son of Dave album), ''01'' (Son of Dave album), 2000
* 01 (Urban ...
.
[E.C. Olson. 1962. "]Late Permian
Late may refer to:
* LATE, an acronym which could stand for:
** Limbic-predominant age-related TDP-43 encephalopathy, a proposed form of dementia
** Local-authority trading enterprise, a New Zealand business law
** Local average treatment effect, ...
terrestrial vertebrates, U.S.A. and U.S.S.R." ''Transactions of the American Philosophical Society, New Series'' 52(2): 1-224 This has proven to be very controversial.
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
Sphenacodontidae
Permian synapsids of North America
Prehistoric synapsid genera
Fossil taxa described in 1953
Taxa named by Everett C. Olson
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