Hibernaspidoidei 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, hibernaspid amphiaspidids are thought to be benthic animals that lived most of their lives mostly buried in the sediment of a series of hypersaline lagoons. All 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, a pair of branchial openings for exhaling, and, in the case of hibernaspids, a simple, slit-like mouth at the anterior end of a tube-like head.

Taxonomy

Hibernaspidoidei contains three families.

Hibernaspididae

This family is

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

, containing only the genus ''

Hibernaspis ''Hibernaspis'' is a genus 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 ex ...

''.

Eglonaspididae

This is a diverse family that contains five monotypic genera, including '' Eglonaspis'', '' Gerronaspis'', '' Lecaniaspis'', '' Empedaspis'', and '' Pelurgaspis''.

Aphataspididae

This family contains two monotypic genera, '' Aphataspis'' and '' Putoranaspis''.

References

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