''Ciderius'' is an extinct genus of jawless fish from the family

Euphaneropidae Euphaneropidae is an extinct family of prehistoric jawless fishes in the extinct order Euphanerida. These fishes are characterised by a greatly elongated branchial apparatus which covers most of the length of the body. Fossils are known from the L ...

, being the oldest known member of the family. It is known from the

Lower Silurian The Silurian ( ) is a geologic period and system spanning 23.5 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 third and shortest period of t ...

Fish Bed Formation The Fish Bed Formation is a geological formation in Scotland, United Kingdom. The fluvial to lacustrine sandstones, shales, siltstones and conglomerates preserve flora, arthropods, among which eurypterids, invertebrates and early fish fossils da ...

Scotland Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land area, consisting of the northern part of the island of Great Britain and more than 790 adjac ...

, and the genus name is derived from cider, due to its resemblance to a bottle, a barrel and a pair of apples when flattened.

Discovery and naming

The earliest discovered specimens belonging to ''Ciderius'' were discovered during the early 20th century, and the genus is known exclusively from several outcrops of the

. The

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

is MAB 6000, a complete specimen in the collections of the Oertijdmuseum De Groene Poort. Other specimens are known, including the paratypes MAB 6001-6004. The holotype and paratypes were discovered with the aid of David John Cooper in the

Central Lowlands The Central Lowlands, sometimes called the Midland Valley or Central Valley, is a geologically defined area of relatively low-lying land in southern Scotland. It consists of a rift valley between the Highland Boundary Fault to the north and ...

, Scotland. The species ''Ciderius cooperi'' was named by Gambit van der Brugghen in 2015. Several hundred specimens were described, although most are fragmentary.

Description

The known remains of ''Ciderius'' suggest it grew up to at least long, and the specimens also preserved soft tissues. The head of ''Ciderius'' was sectioned into three parts, and it likely possessed sclerotic rings. It also had a 'visceral cavity' similar to '' Euphanerops''.Janvier, P. & Arsenault, M., (2007). The anatomy of ''Euphanerops longaevus'', an anaspid-like jawless vertebrate from the Upper Devonian. ''Geodiversitas'' 29: 143–216. The only parts of the animal that were not preserved in a lateral aspect were skin impressions, traces of fins and the head region.

Classification

van der Brugghen (2015) classified ''Ciderius'' as the oldest known member of the

, a family of jawless fishes.

References

External links

* Anaspidomorphi Fossil taxa described in 2015 Anaspidomorphi genera {{paleo-jawless-fish-stub