''Anconastes'' is an extinct

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

dissorophoid Dissorophoidea is a clade of medium-sized, temnospondyl amphibians that appeared during the Moscovian in Euramerica, and continued through to the Late Permian and the Early Triassic of Gondwana. They are distinguished by various details of the ...

temnospondyl Temnospondyli (from Greek language, Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') or temnospondyls is a diverse ancient order (biology), order of small to giant tetrapods—often considered Labyrinth ...

within the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Trematopidae Trematopidae is a family of dissorophoid temnospondyls spanning the late Carboniferous to the early Permian. Together with Dissorophidae, the family forms Olsoniformes, a clade comprising the medium-large terrestrial dissorophoids. Trematopids a ...

. It is known from two specimens from the

Late Carboniferous Late or LATE may refer to: Everyday usage * Tardy, or late, not being on time * Late (or the late) may refer to a person who is dead Music * Late (The 77s album), ''Late'' (The 77s album), 2000 * Late (Alvin Batiste album), 1993 * Late!, a pseudo ...

Cutler Formation The Cutler Formation or Cutler Group is a stratigraphic unit 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. Desc ...

of north-central

New Mexico New Mexico is a state in the Southwestern United States, Southwestern region of the United States. It is one of the Mountain States of the southern Rocky Mountains, sharing the Four Corners region with Utah, Colorado, and Arizona. It also ...

in the southwestern United States. The genus name derives from two Greek roots, ''ankos'' ("mountain glen or valley") and ''nastes'' ("inhabitant"), which refers to the type locality of El Cobre Canyon where the specimens were found. The specific name is derived from the Latin word ''vesperus'' ("western"). The more complete specimen, the

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

, is a partial skull with articulated mandibles and a substantial amount of the postcranial skeleton. The less complete specimen, the paratype, consists only of the right margin of the skull with an articulated mandible.

Anatomy

When originally described, only three other trematopid taxa were recognized: ''

Acheloma ''Acheloma'' (also known as ''Trematops milleri'') is an extinct genus of temnospondyl that lived during the Early Permian. The type species is ''A. cumminsi''. History of study ''Acheloma'' was named by Edward Drinker Cope in 1882 based on ...

Actiobates ''Actiobates'' is an extinct genus of trematopid temnospondyl that lived during the Late Carboniferous. It is known from the Garnett Quarry in Kansas. History of study ''Actiobates peabodyi'' was named in 1973 by Theodore Eaton. The genus name ...

'', and "''

Trematops ''Acheloma'' (also known as ''Trematops milleri'') is an extinct genus of temnospondyl that lived during the Early Permian. The type species is ''A. cumminsi''. History of study ''Acheloma'' was named by Edward Drinker Cope in 1882 based on ...

''" (now a synonym of ''Acheloma''); ''

Ecolsonia ''Ecolsonia'' is an extinct genus of trematopid temnospondyl. Its phylogenetic position within Olsoniformes has been historically debated, but it is presently considered to be a trematopid. History of study The holotype of ''Ecolsonia'' is a ...

'', which is now considered a trematopid by most workers, had recently been re-described as a dissorophid on the basis of new material. Berman et al. suggested two autapomorphies: (1) an internal naris that is half as wide as it is long; and (2) a dense covering of non-overlapping scales or osteoderms in the dorsal trunk region. They further differentiated ''Anconastes'' from ''Acheloma'' and "''Trematops''" by several features: (1) large orbit with a width equal to 1/3 the midline length of the skull; (2) a short suborbital bar with a maxilla entering the orbital margin; (3) pointed snout without prominent dorsomedial expansion of the postparietals; (4) nasals, frontals, and parietals of subequal length; (5) parietals approximately three times the length of the postparietals; (6) frontals not extending beyond the anterior margin of the orbit; (7) large interpterygoid vacuities; (8) an open basicranial joint; and (9) absence of an internarial opening or bone. They differentiated ''Anconastes'' from ''Actiobates'' by the presence of a quadratojugal contributing substantially to the ventral margin of the otic notch. More recent review work has refined the diagnostic features to a handful of the original features proposed by Berman et al. with the study of additional trematopid material and the description of new taxa.

Relationships

''Anconastes'' is an uncontroversial trematopid and is most often recovered as the sister taxon to ''

Tambachia ''Tambachia'' is an extinct genus of dissorophoid temnospondyl within the family Trematopidae. It is known from the Early Permian Tambach Formation (the lowermost unit of the Upper Rotliegend) near the town of Tambach-Dietharz in Thuringia, Ger ...

'' from the early Permian Bromacker Quarry in Germany. Below is the topology from Polley & Reisz (2011):

References

{{Taxonbar, from=Q4033999 Dissorophidae Trematopidae Carboniferous temnospondyls of North America Carboniferous geology of New Mexico Fossil taxa described in 1987 Prehistoric amphibian genera