Osteolaeminae is a

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...

of true crocodiles within the

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 ...

Crocodylidae Crocodiles (family Crocodylidae) or true crocodiles are large semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. The term crocodile is sometimes used even more loosely to include all extant mem ...

containing the dwarf crocodiles and slender-snouted crocodiles, and is the

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 t ...

to Crocodylinae.

Taxonomy

Osteolaeminae was named by Christopher Brochu in 2003 as a subfamily of Crocodylidae separate from Crocodylinae, and is

cladistically Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived chara ...

defined as ''Osteolaemus tetraspis'' (the Dwarf crocodile) and all

crocodylians Crocodilia (or Crocodylia, both ) is an order of mostly large, predatory, semiaquatic reptiles, known as crocodilians. They first appeared 95 million years ago in the Late Cretaceous period (Cenomanian stage) and are the closest living ...

more closely related to it than to ''Crocodylus niloticus'' (the

Nile crocodile The Nile crocodile (''Crocodylus niloticus'') is a large crocodilian native to freshwater habitats in Africa, where it is present in 26 countries. It is widely distributed throughout sub-Saharan Africa, occurring mostly in the central, eastern ...

). This is a stem-based definition, and is the

to Crocodylinae. Osteolaeminae contains the two

extant Extant is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Extant taxon, a taxon which is not extinct, ...

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

Osteolaemus ''Osteolaemus'' is a genus of crocodiles. They are small, secretive crocodiles that occur in wetlands of West and Middle Africa. They are commonly known as the African dwarf crocodiles. Unlike other crocodiles, ''Osteolaemus'' are strictly noct ...

'' and ''

Mecistops ''Mecistops'' is a genus of crocodiles, the slender-snouted crocodiles, native to sub-Saharan Africa. Taxonomy and etymology Traditionally placed in ''Crocodylus'', recent studies in DNA and morphology have shown that it is in fact basal to ' ...

'', along with several extinct genera, although the number of extant species within Osteolaeminae is currently in question.

Phylogeny

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 ...

below is based on two studies that combined morphological, molecular (

DNA sequencing DNA sequencing is the process of determining the nucleic acid sequence – the order of nucleotides in DNA. It includes any method or technology that is used to determine the order of the four bases: adenine, guanine, cytosine, and thymine. Th ...

), and

stratigraphic Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has three related subfields: lithostra ...

(

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

age) data. Alternatively, other morphological studies have recovered ''Mecistops'' as a basal member of Crocodylinae, more closely related to '' Crocodylus'' than to ''

'' and the other members of Osteolaeminae, as shown in the

below.

Species list

* Subfamily Osteolaeminae ** Genus ''

'' *** '' Osteolaemus osborni'', Osborn’s dwarf crocodile *** '' Osteolaemus tetraspis'', dwarf crocodile (There has been controversy as to whether or not this is actually two species; recent (2010) DNA analysis indicate three distinct species: ''O. tetraspis'', ''O. osborni'' and a third, currently unnamed.) ** Genus ''

'' ***''

Mecistops cataphractus The West African slender-snouted crocodile (''Mecistops cataphractus''), or slender-snouted crocodile, is a critically endangered species of African crocodile. It is one of five species of crocodile in Africa, the other four being the Central A ...

West African slender-snouted crocodile The West African slender-snouted crocodile (''Mecistops cataphractus''), or slender-snouted crocodile, is a critically endangered species of African crocodile. It is one of five species of crocodile in Africa, the other four being the Central A ...

*** ''

Mecistops leptorhynchus The Central African slender-snouted crocodile (''Mecistops leptorhynchus'') is one of two species of crocodiles in the genus ''Mecistops''. It was once thought to be a population of the West African slender-snouted crocodile (''Mecistops cataph ...

Central African slender-snouted crocodile The Central African slender-snouted crocodile (''Mecistops leptorhynchus'') is one of two species of crocodiles in the genus ''Mecistops''. It was once thought to be a population of the West African slender-snouted crocodile (''Mecistops cataph ...

** Genus '' Brochuchus'' *** ''

Brochuchus pigotti ''Brochuchus'' is an extinct genus of crocodile known from the Early Miocene Hiwegi Formation of Rusinga Island in Lake Victoria, Kenya; it was originally named as a species of '' Crocodylus''. It contains two species, ''B. parvidens'' and ''B ...

'' (formerly ''Crocodylus pigotti'') *** '' Brochuchus parvidens'' ** Genus ''

Euthecodon ''Euthecodon'' is an extinct genus of long-snouted crocodile. It was common throughout much of Africa during the Neogene, with fossils being especially common in Kenya, Ethiopia, and Libya. Although superficially resembling that of gharials, the ...

'' *** ''

Euthecodon nitriae ''Euthecodon'' is an extinct genus of long-snouted crocodile. It was common throughout much of Africa during the Neogene, with fossils being especially common in Kenya, Ethiopia, and Libya. Although superficially resembling that of gharials, t ...

'' *** ''

Euthecodon brumpti ''Euthecodon'' is an extinct genus of long-snouted crocodile. It was common throughout much of Africa during the Neogene, with fossils being especially common in Kenya, Ethiopia, and Libya. Although superficially resembling that of gharials, the ...

'' *** '' Euthecodon arambourgi'' ** Genus '' Rimasuchus'' *** ''

Rimasuchus lloydi ''Rimasuchus'' is an extinct genus of crocodile from the Miocene of Egypt and possibly Libya. Only one species - ''Rimasuchus lloydi'' - is currently known. It was previously thought to be a species of '' Crocodylus'', but is now thought to be ...

'' (formerly ''Crocodylus lloydi'')

References

{{Taxonbar, from=Q21541686 Crocodylidae Tetrapod subfamilies