''Cutleria'' is an extinct

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 n ...

basal Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''. Science * Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure * Basal (medicine), a minimal level that is nec ...

sphenacodontids or derived stem-

sphenacodontoid Sphenacodontoidea is a node-based taxon, node-based clade that is defined to include the most recent common ancestor of Sphenacodontidae and Therapsida and its descendants (including mammals). Sphenacodontoids are characterised by a number of syn ...

known from 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), 2001 * ''01'' (Son of Dave album), 2000 * ''01'' (Urban Zakapa album), 2011 * ''O1'' (Hiroyuki Sawano ...

period (

Sakmarian In the geologic timescale, the Sakmarian is an age or stage of the Permian. It is a subdivision of the Cisuralian Epoch or Series. The Sakmarian lasted between 293.52 and million years ago (Ma). It was preceded by the Asselian and followed b ...

stage) of the

Colorado Colorado (, other variants) is a state in the Mountain states, Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the wes ...

, United States. It contains a single species, ''Cutleria wilmarthi''.

Discovery

''Cutleria'' is known only from the

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 seve ...

specimen USNM 22099, a fractured but three-dimensionally preserved, a nearly complete

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, t ...

and articulated partial

postcrania Postcrania (postcranium, adjective: postcranial) in zoology and vertebrate paleontology is all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g. of dinosaurs or other extinct tetrapods, consist of partial or isolated s ...

skeleton A skeleton is the structural frame that supports the body of an animal. There are several types of skeletons, including the exoskeleton, which is the stable outer shell of an organism, the endoskeleton, which forms the support structure inside ...

(including

vertebral column The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate in which the notochord (a flexible rod of uniform composition) found in all chordate ...

rib In vertebrate anatomy, ribs ( la, costae) are the long curved bones which form the rib cage, part of the axial skeleton. In most tetrapods, ribs surround the chest, enabling the lungs to expand and thus facilitate breathing by expanding the ch ...

s and several girdle and limb elements). It was collected at locality 3, near Placerville of

San Miguel County, Colorado San Miguel County is a county located in the U.S. state of Colorado. As of the 2020 census, the population was 8,072. The county seat is Telluride. The county is named for the San Miguel River. History San Miguel County was given the Spanish ...

, from the

Cutler Formation The Cutler Formation or Cutler Group is a rock unit that is exposed across the U.S. states of Arizona, northwest New Mexico, southeast Utah and southwest Colorado. It was laid down in the Early Permian during the Wolfcampian epoch. Descr ...

, dating to the

stage of the

Cisuralian The Cisuralian is the first series/epoch of the Permian. The Cisuralian was preceded by the Pennsylvanian and followed by the Guadalupian. The Cisuralian Epoch is named after the western slopes of the Ural Mountains in Russia and Kazakhstan and ...

series. MCZ 2987, a tip of the rostrum and some teeth collected 2.5 km from the type locality (from localities 11-13), was originally referred to ''C. wilmarthi'' by Lewis and Vaughn (1965). A redescription of sphenacodonts by

Michel Laurin Michel Laurin is a Canadian-born French vertebrate paleontologist whose specialities include the emergence of a land-based lifestyle among vertebrates, the evolution of body size and the origin and phylogeny of lissamphibians. He has also made impo ...

(1993 and 1994), revealed that it can't be assigned to any named sphenacodont genus. Although its teeth also bear cutting edges without serrations, they are more

bulbous In botany, a bulb is structurally a short stem with fleshy leaves or leaf basesBell, A.D. 1997. ''Plant form: an illustrated guide to flowering plant morphology''. Oxford University Press, Oxford, U.K. that function as food storage organs duri ...

, not as strongly compressed

lateral Lateral is a geometric term of location which may refer to: Healthcare *Lateral (anatomy), an anatomical direction * Lateral cricoarytenoid muscle * Lateral release (surgery), a surgical procedure on the side of a kneecap Phonetics *Lateral co ...

ly and not curved

distal Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

ly. A new genus wasn't erected for MCZ 2987, as it is very fragmentary and lacks sufficient diagnostic features.

Description

''Cutleria'' was assigned to the Haptodontinae by Lewis and Vaughn (1965) on the basis of similarities to '' Haptodus baylei'' and '' H. longicaudata'' (now '' Palaeohatteria''). Currie (1977) described the second haptodontine from North America, '' Haptodus garnettensis''. In 1979, he synonymized all European haptodontines, as well as ''C. wilmarthi'', with ''H. baylei''. Later, Laurin (1993 and 1994) considered Haptodontinae to represent a

polyphyletic A polyphyletic group is an assemblage of organisms or other evolving elements that is of mixed evolutionary origin. The term is often applied to groups that share similar features known as homoplasies, which are explained as a result of conver ...

grade of basal sphenacodonts, and revalidated ''Cutleria'' among other genera and species. His revision has been accepted since. Only three

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

analyses included ''Cutleria''. Laurin (1994) and Fröbisch ''et al.'' (2011) recovered ''Cutleria'' as the sister taxon of

Sphenacodontoidea Sphenacodontoidea is a node-based clade that is defined to include the most recent common ancestor of Sphenacodontidae and Therapsida and its descendants (including mammals). Sphenacodontoids are characterised by a number of synapomorphies conce ...

, while the significantly larger analysis of Benson (in press) recovered it as the

basalmost In phylogenetics, basal is the direction of the ''base'' (or root) of a rooted phylogenetic tree or cladogram. The term may be more strictly applied only to nodes adjacent to the root, or more loosely applied to nodes regarded as being close to ...

sphenacodontid. Benson (in press) listed three

synapomorphies In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to hav ...

between ''Cutleria'' and more derived sphenacodontids: their frontal is more than 2.5 times the length of the parietal (as it was noted by Laurin in 1994), a strongly posteroventrally inclined temporal roof (absent in ''

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 ...

''), and a lateral centrale that covers the proximal ends of the first-third distal carpals. However, only one additional step was required to place ''Cutleria'' outside Sphenacodontidae, as the sister taxon of Sphenacodontoidea (which is the node "Therapsida + Sphenacodontidae"). The

cladogram 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 ...

below shows ''Cutleria'' phylogenetic position among other synapsids following Benson (2012).

Etymology

''Cutleria'' was first described and named by George Edward Lewis and Peter Paul Vaughn in

1965 Events January–February * January 14 – The Prime Minister of Northern Ireland and the Taoiseach of the Republic of Ireland meet for the first time in 43 years. * January 20 ** Lyndon B. Johnson is Second inauguration of Lyndo ...

and 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 specimen( ...

is ''Cutleria wilmarthi''. The generic name is derived from the name of the

in which the holotype was found. The specific name honors Wilmarth for finding the holotype.

References

{{Taxonbar, from=Q5196889 Sphenacodontidae Fossil taxa described in 1965 Cisuralian synapsids of North America Prehistoric synapsid genera Cisuralian genus first appearances