Ankyramorpha ("anchor forms") is an extinct clade of

procolophonomorph Procolophonomorpha is an order or clade containing most parareptiles. Many papers have applied various definitions to the name, though most of these definitions have since been considered synonymous with modern parareptile clades such as Ankyra ...

parareptile Parareptilia ("at the side of reptiles") is a subclass or clade of basal sauropsids (reptiles), typically considered the sister taxon to Eureptilia (the group that likely contains all living reptiles and birds). Parareptiles first arose near the ...

s which lived between the early

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 ...

epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided by ...

(middle

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) to the latest

Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago (Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...

period (latest

Rhaetian The Rhaetian is the latest age of the Triassic Period (in geochronology) or the uppermost stage of the Triassic System (in chronostratigraphy). It was preceded by the Norian and succeeded by the Hettangian (the lowermost stage or earliest ...

stage) of

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest co ...

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an ...

, Australia,

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located enti ...

, North America and

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the souther ...

.Jalil, N. E., & Janvier, P. (2005). Les pareiasaures (Amniota, Parareptilia) du Permien supérieur du Bassin d’Argana, Maroc. Geodiversitas, 27(1), 35-132. This clade was named in a

1996 File:1996 Events Collage.png, From left, clockwise: A bomb explodes at Centennial Olympic Park in Atlanta, set off by a radical anti-abortionist; The center fuel tank explodes on TWA Flight 800, causing the plane to crash and killing everyone on b ...

parareptile study by Michael deBraga and

Robert R. Reisz Robert Rafael Reisz is a Canadian paleontologist and specialist in the study of early amniote and tetrapod evolution. Research career Reisz received his B.Sc. (1969), M.Sc. (1971) and Ph.D. (1975) from McGill University as Robert L. Carro ...

. They provided the name Ankyramorpha for a newly recognized clade encompassing "the most recent common ancestor of

Procolophonia The Procolophonia are a suborder of herbivorous reptiles that lived from the Middle Permian till the end of the Triassic period. They were originally included as a suborder of the Cotylosauria (later renamed Captorhinida Carroll 1988) but ar ...

and

Lanthanosuchoidea Lanthanosuchoidea is an extinct superfamily of ankyramorph parareptiles from the middle Pennsylvanian to the middle Guadalupian epoch (Moscovian - Wordian stages) of Europe, North America and Asia. It was named by the Russian paleontologist ...

and all its descendants", and this clade name sees continued use among modern parareptile studies. A similar name, Hallucicrania, was provided in an earlier

1995 File:1995 Events Collage V2.png, From left, clockwise: O.J. Simpson is acquitted of the murders of Nicole Brown Simpson and Ronald Goldman from the year prior in "The Trial of the Century" in the United States; The Great Hanshin earthquake strike ...

study by Michael S. Y. Lee, who defined it as the

node-based taxon Phylogenetic nomenclature is a method of nomenclature for taxa in biology that uses phylogenetic definitions for taxon names as explained below. This contrasts with the traditional approach, in which taxon names are defined by a ''type'', which c ...

formed by the

most recent common ancestor In biology and genetic genealogy, the most recent common ancestor (MRCA), also known as the last common ancestor (LCA) or concestor, of a set of organisms is the most recent individual from which all the organisms of the set are descended. The ...

of lanthanosuchids and "pareiasauroids" (

pareiasaur Pareiasaurs (meaning "cheek lizards") are an extinct clade of large, herbivorous parareptiles. Members of the group were armoured with scutes which covered large areas of the body. They first appeared in southern Pangea during the Middle Permia ...

s + ''

Sclerosaurus ''Sclerosaurus'' is an extinct genus of procolophonid parareptile known from the Early to Middle Triassic of Germany and Switzerland. It contains a single species, ''Sclerosaurus armatus''. It was fairly small about 30 cm long, distingu ...

''), and all its descendants. Unlike Ankyramorpha, which explicitly included

procolophonoid Procolophonoidea is an extinct superfamily of procolophonian parareptiles. Members were characteristically small, stocky, and lizard-like in appearance. Fossils have been found worldwide from many continents including Antarctica. The first mem ...

s, Hallucicrania was originally designed to exclude procolophonoids, which Lee's analysis argued to have split off prior to the divergence between lanthanosuchids and pareiasaurs. Nevertheless, purely considering the taxa encompassed by their definitions, Hallucicrania and Ankyramorpha refer to an identical grouping. The following

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 ...

is simplified after the phylogenetic analysis of MacDougall and Reisz (2014) and shows the placement of Ankyramorpha within

Parareptilia Parareptilia ("at the side of reptiles") is a subclass or clade of basal sauropsids ( reptiles), typically considered the sister taxon to Eureptilia (the group that likely contains all living reptiles and birds). Parareptiles first arose near ...

. Relationships within emboldened terminal clades are not shown.

References

Procolophonomorphs Permian reptiles Triassic reptiles Permian reptiles of South America Early Triassic reptiles of South America Middle Triassic reptiles of South America Late Triassic reptiles of South America Cisuralian first appearances Late Triassic extinctions {{paleo-reptile-stub