''Heterosteus'' (also known as ''Heterostius''
) is an
extinct
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
heterosteid placoderm of the
Middle Devonian known from remains discovered in
Europe
Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...
and
Greenland
Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland is t ...
.
Name
''Heterosteus'' was originally
described in 1837 as species of ''
Trionyx'', a softshelled turtle. Also in later studies it was often misidentified and given names like ''Ichthyosauroides'', ''
Asterolepis asmussi'' and ''Chelonichthys asmusii''.
[ Even in recent studies, it is controversial as to whether to use genus name ''Heterosteus'' or ''Heterostius''. According to ]International Code of Zoological Nomenclature
The International Code of Zoological Nomenclature (ICZN) is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals. It is also informally known as the ICZN Code, for its publisher, the ...
, suffix ‘-ostius’ in scientific name
In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...
should not be corrected as ‘-osteus’, so some study uses genus name ''Heterostius''.[
]
Description
This genus includes the largest species in the family, and are among the largest arthrodires
Arthrodira (Greek for "jointed neck") is an order of extinct armored, jawed fishes of the class Placodermi that flourished in the Devonian period before their sudden extinction, surviving for about 50 million years and penetrating most marine ec ...
, as well, with the type species, ''H. asmussi'', having an estimated body length of up to .
Phylogeny
''Heterosteus'' is the type genus for 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 ...
Heterosteidae
Heterosteidae (also known as Heterostiidae) is an extinct family of moderately large to giant, flattened, benthic arthrodire placoderms with distinctive, flattened, triangular skulls that are extremely broad posteriorly, but become very narrow ...
, which belongs to the superfamily
SUPERFAMILY is a database and search platform of structural and functional annotation for all proteins and genomes. It classifies amino acid sequences into known structural domains, especially into SCOP superfamilies. Domains are functional, str ...
Dunkleosteoidea. It is a relative of the giant '' Dunkleosteus'', as shown in the cladogram below:[
]
References
{{Taxonbar, from=Q3785387, from2=Q112325922
Arthrodires
Placoderm families
Middle Devonian first appearances
Middle Devonian extinctions
Fossil taxa described in 1844
Fossil taxa described in 1856