Kannemeyeriiformes is a group of large-bodied

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 per ...

dicynodont Dicynodontia is an extinct clade of anomodonts, an extinct type of non-mammalian therapsid. Dicynodonts were herbivorous animals with a pair of tusks, hence their name, which means 'two dog tooth'. Members of the group possessed a horny, typic ...

s. As a

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English ter ...

, Kannemeyeriiformes has been defined to include the species '' Kannemeyeria simocephalus'' and all dicynodonts more closely related to it than to the species ''

Lystrosaurus murrayi ''Lystrosaurus'' (; 'shovel lizard'; proper Greek is λίστρον ''lístron'' ‘tool for leveling or smoothing, shovel, spade, hoe’) is an extinct genus of herbivorous dicynodont therapsids from the late Permian and Early Triassic epochs (a ...

''.

Evolutionary history

Despite being the most species-rich group of dicynodonts in the Triassic Period, kannemeyeriiforms exhibit much less diversity in terms of their anatomy and ecological roles than the dicynodonts from the Permian Period.

Lystrosauridae Lystrosauridae is a family of dicynodont therapsids from the Permian and Triassic time periods. It includes two genera, ''Lystrosaurus'' and '' Kwazulusaurus''. ''Kwazulusaurus'' includes a single species, ''K. shakai'', from the Late Permian of ...

is thought to be the most closely related group (

sister taxon In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

) to Kannemeyeriiformes, and since the earliest lystrosaurids are known 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, ...

, the divergence of these two groups must have occurred at least as far back as this time, implying that a long ghost lineage must exist. Although no kannemeyeriiforms have been found in the Late Permian yet, the recent discovery of '' Sungeodon'' helps fill a gap in the early fossil record of the group by showing that kannemeyeriiforms diversified right after the Permian-Triassic extinction event.Maisch, M. W.; Matzke, A. T. (2014). "Sungeodon kimkraemerae n. gen. n. sp., the oldest kannemeyeriiform (Therapsida, Dicynodontia) and its implications for the early diversification of large herbivores after the P/T boundary". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 272: 1. doi:10.1127/0077-7749/2014/0394. edit

Classification

Four families have been included in the group: Kannemeyeriidae,

Shansiodontidae Shansiodontidae is a family of dicynodont therapsid Therapsida is a major group of eupelycosaurian synapsids that includes mammals, their ancestors and relatives. Many of the traits today seen as unique to mammals had their origin within ear ...

, Stahleckeriidae, and Dinodontosauridae. Occasionally some of these families are not recognized, with most kannemeyeriiforms being placed in Kannemeyeriidae. Recent

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 ...

analyses suggest that these families represent similar body plans or

morphotype In biology, polymorphism is the occurrence of two or more clearly different morphs or forms, also referred to as alternative '' phenotypes'', in the population of a species. To be classified as such, morphs must occupy the same habitat at the ...

s rather than true evolutionary groupings.

Phylogeny

Below is a

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 ...

from Kammerer ''et al.'' (2013):

References

Dicynodonts Triassic synapsids Induan first appearances Rhaetian extinctions Taxa named by Friedrich von Huene {{anomodont-stub