Dissorophoideans are 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 term, ...

of medium-sized,

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

amphibia Amphibians are four-limbed and ectothermic vertebrates of the class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terrestrial, fossorial, arbore ...

ns that appeared during the Moscovian in

Euramerica Laurasia () was the more northern of two large landmasses that formed part of the Pangaea supercontinent from around ( Mya), the other being Gondwana. It separated from Gondwana (beginning in the late Triassic period) during the breakup of Pan ...

, and continued through to 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, ...

and the

Early Triassic The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between Ma and Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which is a un ...

Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages ...

. They are distinguished by various details of the skull, and many forms seem to have been well adapted for life on land. Since 2008,

Lissamphibia The Lissamphibia is a group of tetrapods that includes all modern amphibians. Lissamphibians consist of three living groups: the Salientia (frogs, toads, and their extinct relatives), the Caudata (salamanders, newts, and their extinct relatives), ...

has been progressively widely considered part of this clade, but this position is still disputed by some authors. It is possible that the small Permo-Carboniferous

Micromelerpetontidae Micromelerpetontidae (also spelled Micromelerpetidae) is an extinct family of dissorophoid temnospondyl amphibians that lived from the Late Carboniferous to the Early Permian in what is now Europe, with one Carboniferous species also known from N ...

and the large Late Permian Melosauridae may also belong in this clade.

Phylogeny

An extensive phylogenetic analysis of dissorophoids conducted in 2016 and 2018 found that the families

Dissorophidae Dissorophidae is an extinct family of medium-sized, temnospondyl amphibians that flourished during the late Carboniferous and early Permian periods. The clade is known almost exclusively from North America. History of study Dissorophidae is a ...

and

Trematopidae Trematopidae is a family of dissorophoid temnospondyl 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 ...

are more closely related to each other than either is to the family

Amphibamidae The Amphibamidae are an extinct family of dissorophoid temnospondyls known from Late Carboniferous-Early Permian strata in the United States. Classification Amphibamidae has traditionally included small-bodied, terrestrial dissorophoids. The n ...

. Following a 2008 study, the Dissorophidae-Trematopidae clade was called

Olsoniformes Olsoniformes is a clade of dissorophoid temnospondyls. It includes the families Dissorophidae and Trematopidae. Most members of the clade were highly adapted to a terrestrial lifestyle. The clade was named in 2008 and is defined as the least incl ...

. Below is 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 d ...

from the 2018 analysis:

References

* Huttenlocker, Adam. 2007
Dissorophoidea

Tree of Life Web Project The Tree of Life Web Project is an Internet project providing information about the diversity and phylogeny of life on Earth. This collaborative peer reviewed project began in 1995, and is written by biologists from around the world. The site h ...

* Laurin, M. and Steyer, J-S, 2000
Phylogeny and Apomorphies of Temnospondyls

(reviewed) * Reisz, Robert (no date),
Biology 356 - Major Features of Vertebrate Evolution - The Origin of Tetrapods and Temnospondyls

References

External links

- Palaeos

- Mikko's Phylogeny Archive {{Taxonbar, from=Q137426 Carboniferous temnospondyls Permian temnospondyls Triassic temnospondyls Vertebrate superfamilies