Amphiaspidoidei is a

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 nam ...

of extinct amphiaspidid heterostracan agnathans whose fossils are restricted to Lower Devonian marine strata of

Siberia Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a part of ...

near the Taimyr Peninsula. In life, the amphiaspidids of Amphiaspidoidei are thought to be benthic animals that lived most of their lives mostly buried in the sediment of a series of hypersaline lagoons. Amphiaspids are easily distinguished from other heterostracans in that all of the plates of the cephalothorax armor are fused into a single, muff-like unit, so that the forebody of the living animal would have looked like a potpie or a hot waterbottle with a pair of small, or degenerated eyes flanked by preorbital openings, a pair of branchial openings for exhaling, and a simple, slit-like mouth.

Taxonomy

The superfamily Amphiaspidoidei contains four families.

Amphiaspididae

This family contains two monotypic genera, including the type genus '' Amphiaspis'', and '' Amphoraspis''

Edaphaspididae

This family is monotypic, and contains the monotypic genus '' Edaphaspis''.

Gabreyaspididae

This family contains four genera, '' Gabreyaspis'', '' Prosarctaspis'', '' Pelaspis'', and '' Tareyaspis''.

Olbiaspididae

This family contains three genera, '' Olbiaspis'', '' Kureykaspis'' and '' Angaraspis''.

References

. Devonian jawless fish Prehistoric animal superfamilies Vertebrate superfamilies Devonian fish of Asia Early Devonian fish Fauna of Siberia Fossils of Russia Early Devonian first appearances Devonian extinctions {{Devonian-jawless-fish-stub