Lepidosirenidae is a

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

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 ...

containing the genera ''

Lepidosiren The South American lungfish (''Lepidosiren paradoxa'') is the single species of lungfish found in swamps and slow-moving waters of the Amazon, Paraguay, and lower Paraná River basins in South America. Notable as an obligate air-breather, it ...

'' (the South American lungfish) and ''

Protopterus ''Protopterus'' is the genus of four species of lungfish found in Africa. ''Protopterus'' was formerly thought to be the sole genus in the family Protopteridae, but more recent studies have classified it with ''Lepidosiren'' in the family Lepi ...

'' (the African lungfish). Both genera were formerly thought to represent the distinct families Lepidosirenidae and Protopteridae within the order Lepidosireniformes, but a 2017 study analyzing all post-

Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...

lungfish taxa found them to be better classified as different genera in a single family.

Taxonomy

Their closest living relatives are of the family

Neoceratodontidae Neoceratodontidae is a family of lungfish containing the extant Australian lungfish and several extinct genera. It and Lepidosirenidae represent the only lungfish families still extant. Fossils from this family are first known from Triassic-aged ...

, or the

Australian lungfish The Australian lungfish (''Neoceratodus forsteri''), also known as the Queensland lungfish, Burnett salmon and barramunda, is the only surviving member of the family Neoceratodontidae. It is one of only six extant lungfish species in the world. ...

, with both families being members of the suborder

Ceratodontoidei Ceratodontoidei is a suborder of lungfish that is defined as "the clade including all taxa more closely related to ''South American lungfish, Lepidosiren'', ''Australian lungfish, Neoceratodus'' and ''Gnathorhiza'' than to ''Uronemus'', ''Conchop ...

. However, their closest relatives in general are of the extinct

Gnathorhizidae The Gnathorhizidae are an extinct family of lungfish that lived from the late Carboniferous until the middle Triassic. Gnathorhizid fossils have been found in North America, Madagascar, Australia, and possibly Eastern Europe and South Africa. ...

, which forms a sister group to Lepidosirenidae. The clade containing both families forms a sister group to the extinct family Ptychoceratodontidae. The earliest fossils of the family come from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...

(

Campanian The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campanian s ...

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval ...

) of

Sudan Sudan ( or ; ar, السودان, as-Sūdān, officially the Republic of the Sudan ( ar, جمهورية السودان, link=no, Jumhūriyyat as-Sūdān), is a country in Northeast Africa. It shares borders with the Central African Republic t ...

, but

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 o ...

evidence indicates the two genera split at the very beginning of the

Early Cretaceous The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Pro ...

, around 145 MYA, and the family itself originated during the end-

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 ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...

period.

Biology

All lungfish of the order can and often do estivate (except the Spotted African lungfish, which can but rarely does so). All members of the order are obligatory air-breathers; only the Australian lungfish has functioning

gills A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...

when adult; members of the Lepidosirenidae have gills only when they are larvae. The lungfish also all have generally small scales and two lungs as opposed to the Australian lungfish's single lung.

References

{{Taxonbar, from1=Q11832577, from2=Q150624 Taxa named by Charles Lucien Bonaparte Lungfish Fish families Extant Cenomanian first appearances