Ceratodontoidei is a suborder of

lungfish Lungfish are freshwater vertebrates belonging to the order Dipnoi. Lungfish are best known for retaining ancestral characteristics within the Osteichthyes, including the ability to breathe air, and ancestral structures within Sarcopterygii, i ...

that is defined as "the clade including all taxa more closely related to '' Lepidosiren'', ''

Neoceratodus ''Neoceratodus'' is a genus of lungfish in the family Neoceratodontidae. The extant Australian lungfish (''Neoceratodus forsteri'') is the only surviving member of this genus, but it was formerly much more widespread, being distributed througho ...

'' and ''

Gnathorhiza ''Gnathorhiza'' is an extinct genus of prehistoric lobe-finned fish (lungfish) which lived during the Permian period and Early Triassic epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the or ...

'' than to '' Uronemus'', ''

Conchopoma ''Conchopoma'' is an extinct genus of lungfish which lived during the Carboniferous The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ...

'' and ''

Sagenodus ''Sagenodus'' is an extinct genus of prehistoric lungfish. It is a lungfish from the Permo-Carboniferous period found in Europe and North America. See also * Sarcopterygii * List of sarcopterygians * List of prehistoric bony fish A ''list'' ...

''". Members of this suborder are known as ceratodontoids. The only presently extant lungfish in the families Neoceratodontidae and

Lepidosirenidae Lepidosirenidae is a family of lungfish containing the genera '' Lepidosiren'' (the South American lungfish) and '' Protopterus'' (the African lungfish). Both genera were formerly thought to represent the distinct families Lepidosirenidae and Pro ...

belong to this suborder.

Taxonomy

The suborder was formerly defined as being within the order

Ceratodontiformes Ceratodontoidei is a suborder of lungfish that is defined as "the clade including all taxa more closely related to ''Lepidosiren'', '' Neoceratodus'' and '' Gnathorhiza'' than to '' Uronemus'', '' Conchopoma'' and ''Sagenodus''". Members of this ...

and including the families Neoceratodontidae and

Ceratodontidae Ceratodontidae is an extinct family of lungfish with fossils known from the earliest Triassic to the Eocene. Taxonomy Although the extant Queensland lungfish was formerly also classified in this family due to its similar appearance, phylogene ...

, as they were formerly thought to be closely related to one another. However, phylogenetic analyses indicate that this classification is

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

, as Ceratodontidae was found to be a

sister group 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 a clade containing Lepidosirenidae, which was formerly classified as

Lepidosireniformes Lev Berg Lev Semyonovich Berg, also known as Leo S. Berg (russian: Лев Семёнович Берг; 14 March 1876 – 24 December 1950) was a leading Russian geographer, biologist and ichthyologist who served as President of the Soviet Geogra ...

, a distinct order from Ceratodontiformes. Due to this, Lepidosireniformes and Ceratodontiformes were redefined as families within the order

Dipnoi Lungfish are freshwater vertebrates belonging to the order Dipnoi. Lungfish are best known for retaining ancestral characteristics within the Osteichthyes, including the ability to breathe air, and ancestral structures within Sarcopterygii, in ...

, and Ceratodontei was redefined as including all lungfish more closely allied with Neoceratodontidae and Lepidosirenidae. The current taxa within the suborder are listed below: The oldest fossils from this suborder are of Gnathorhizidae from the

Late Carboniferous 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 effe ...

. Phylogenetic evidence indicates that the suborder itself originated slightly earlier in the late Carboniferous and rapidly diversified into the multiple families between then and the start of the

Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Pale ...

References

{{Taxonbar, from=Q21230686 Lungfish Extant Pennsylvanian first appearances Fish suborders