''Auchenaspis salteri'' is an extinct species of armored jawless fish of the

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...

Thyestiida Thyestiida is an order of bony-armored jawless fish in the extinct vertebrate class Osteostraci The class Osteostraci (meaning "bony shells") is an extinct taxon of bony-armored jawless fish, termed "ostracoderms", that lived in what is now ...

from the Late

Silurian The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozo ...

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...

. In England, ''A. salteri'''s fossils are found in extreme abundance in the Lower Old Red Sandstone strata in

Ledbury Ledbury is a market town and civil parish in the county of Herefordshire, England, lying east of Hereford, and west of the Malvern Hills. It has a significant number of timber-framed structures, in particular along Church Lane and High Street ...

Herefordshire Herefordshire () is a county in the West Midlands of England, governed by Herefordshire Council. It is bordered by Shropshire to the north, Worcestershire to the east, Gloucestershire to the south-east, and the Welsh counties of Monmouthshire ...

. ''A. salteri'' strongly resembles the thyestiids ''

Procephalaspis ''Procephalaspis'' is an extinct genus of jawless fish Agnatha (, Ancient Greek 'without jaws') is an infraphylum of jawless fish in the phylum Chordata, subphylum Vertebrata, consisting of both present (cyclostomes) and extinct (conodonts a ...

'' and ''

Thyestes In Greek mythology, Thyestes (pronounced , gr, Θυέστης, ) was a king of Olympia. Thyestes and his brother, Atreus, were exiled by their father for having murdered their half-brother, Chrysippus, in their desire for the throne of Olym ...

'', and within Thyestiida, it represents a transitional form between the primitive, superficially ''

Cephalaspis ''Cephalaspis'' (from el, κεφαλή , 'head' and el, ἀσπίς , 'shield') is a possibly monotypic genus of extinct osteostracan agnathan vertebrate. It was a trout-sized detritivorous fish that lived in the early Devonian. Description L ...

''-like forms, such as ''Thyestes'', and the more specialized tremataspid thyestiids, like ''

Tremataspis ''Tremataspis'' is a genus of an extinct osteostracan agnathan from the Silurian period of what is now Estonia. ''Tremataspis'' was about in length, and had an armored shield covering its head. Compared with its relatives, the shield was unusu ...

'', ''

Dartmuthia ''Dartmuthia'' is an extinct genus of primitive jawless fish that lived in the Silurian period. Fossils of ''Dartmuthia'' have been found in Himmiste Quarry, on the island of Saaremaa in Estonia Estonia, formally the Republic of Estonia, ...

'', or '' Dobraspis'', whose headshields tend to resemble hot buns or horseshoe crabs.

References

Osteostraci genera Silurian fish of Europe Fossils of Great Britain {{Paleo-jawless-fish-stub