''Ctenorhachis'' (Greek for "comb spine") is an extinct genus of the family

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 ...

. ''Ctenorhachis'' was 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 ...

'', but did not belong to the same subfamily as ''Dimetrodon'' 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 ...

'', being a more basal member of Sphenacodontidae. ''Ctenorhachis'' lived 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 ...

epoch. Two specimens are known that have been found from the

Wichita Group The Wichita Group is a geologic group in the Texas Red Beds. It preserves fossils dating back to the Permian period. See also * List of fossiliferous stratigraphic units in Texas * Paleontology in Texas Paleontology in Texas refers to paleo ...

outcropping in Baylor and

Archer Archery is the sport, practice, or skill of using a bow to shoot arrows.Paterson ''Encyclopaedia of Archery'' p. 17 The word comes from the Latin ''arcus'', meaning bow. Historically, archery has been used for hunting and combat. In mo ...

counties, north-central Texas. Only the

vertebrae The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic i ...

and

pelvis The pelvis (plural pelves or pelvises) is the lower part of the trunk, between the abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also called bony pelvis, or pelvic skeleton). The ...

are known. Articulated vertebrae from the holotype specimen possess blade like neural spines that are greatly enlarged, although not nearly to the extent that can be seen in more derived sphenacodontids such as ''Dimetrodon'' and ''

Secodontosaurus ''Secodontosaurus'' (meaning "cutting-tooth lizard") is an extinct genus of "pelycosaur" synapsids that lived from between about 285 to 272 million years ago during the Early Permian. Like the well known ''Dimetrodon'', ''Secodontosaurus'' is a c ...

'', in which they form a large sail. The pelvis is nearly identical to that of ''Dimetrodon''. As suggested in the original description of the genus, ''Ctenorhachis'' may represent a short-spined sexual dimorph, although the authors find this unlikely.Hook, R. W. and N. Hotton (1991). A New Sphenacodontid Pelycosaur (Synapsida) from the Wichita Group, Lower Permian of North-Central Texas. ''Journal of Vertebrate Paleontology'' 11(1):37-44.

References

Sphenacodontidae Prehistoric synapsid genera Cisuralian synapsids of North America Taxa named by Nicholas Hotton III Fossil taxa described in 1991 Artinskian genus first appearances Artinskian genus extinctions {{Paleo-Synapsid-stub