Eriptychiida is an extinct

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...

taxon In biology, a taxon ( back-formation from '' taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular n ...

vertebrate Vertebrates () comprise all animal taxon, taxa within the subphylum Vertebrata () (chordates with vertebral column, backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the ...

in the group

Pteraspidomorphi Pteraspidomorphi is an extinct class of early jawless fish. They have long been regarded as closely related or even ancestral to jawed vertebrates, but the few characteristics they share with the latter are now considered as basal traits for al ...

. The order contains the

genus 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 n ...

, '' Eriptychius'', and

fossilized 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 ...

specimens from this genus have been found in the Gull River Formation of

Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central C ...

, the Harding Formation of

Colorado Colorado (, other variants) is a state in the Mountain states, Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the wes ...

, and the Bighorn Dolomite of

Wyoming Wyoming () is a state in the Mountain West subregion of the Western United States. It is bordered by Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho to the west, Utah to the southwest, and Colorado to the sou ...

. The group contains two documented

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

: ''Eriptychius americanus'' and ''Eriptychius orvigi''.

Characteristics

The structure of the dentine of eriptychiids is in many respects closer to that of

heterostraca Heterostraci ( Ancient Greek, ἕτερος+ὄστρακον "those itha different shell" i is pl. of -us is an extinct subclass of pteraspidomorph jawless vertebrate that lived primarily in marine and estuary environments. Heterostraci e ...

ns that to that of astraspids. This is the only argument to place them as the closest relatives to heterostracans, among the Ordovician vertebrates. However, eriptychiids differ from all other pteraspidomorphs in having a massively calcified endoskeleton, pervaded by canals for blood vessels.

Taxonomy

* Order † Eriptychiiformes Ørvig 1958 ** Genus ?†'' Eleochera'' Sansom & Smith 2005 ** Family † Eriptychiidae Tarlo 1962 *** Genus †'' Eriptychius'' Walcott 1892 ** Family † Oniscolepididae Märss & Karatajūtė-Talimaa 2009 *** Genus †'' Kallostrakon'' Lankester 1870 *** Genus †'' Oniscolepis'' Pander 1856 non Groß 1961 'Strosipherus'' Pander 1856

References

External links

Eriptychiida
Pteraspidomorphi Prehistoric jawless fish orders Ordovician jawless fish Late Ordovician animals Ordovician fish of North America Late Ordovician first appearances Late Ordovician taxonomic orders Late Ordovician extinctions {{ordovician-animal-stub de:Pteraspidomorphi#Eriptychiida

Characteristics

Taxonomy

See also

References

External links