''Westrichus'' is an extinct

acanthodian Acanthodii or acanthodians is an extinct class of Gnathostomata, gnathostomes (jawed fishes). They are currently considered to represent a paraphyletic Evolutionary grade, grade of various fish lineages Basal (phylogenetics), basal to extant tax ...

which lived in the Lower Permian of Germany. It contains two species: the type species, ''Westrichus kraetschmeri'', and ''Westrichus tholeyi'', the latter of which was previously assigned to ''

Acanthodes ''Acanthodes'' (from , 'provided with spines') is an extinct genus of acanthodian fish. Species have been found in Europe, North America, and Asia, spanning the Early Carboniferous to the Early Permian, making it one of the youngest known acanth ...

''.

Description

This animal was very similar to the genus ''

'', however it was equipped with an extremely elongated pelvic fin; it started behind the head and ended just before the retracted anal fin. The appearance, compared to that of ''Acanthodes'', was therefore much more massive, however, the head was smaller. It had length up to , and like all acanthodians, ''Westrichus'' had large spines on its fins. The

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

was small and pointed backward, and was located near the larger and elongated anal fin.

Classification

First described in 2003 on the basis of

fossils 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 ...

found in the Meisenheim Formation, ''Westrichus'' is considered a very specialised acanthodian. Like many derived representatives of the group, ''Westrichus'' had a low number of fins. It is considered a close relative of the genus ''Acanthodes'', in the family

Acanthodidae Acanthodiformes (alternatively spelled Acanthodida) is an Order (biology), order of "Acanthodii, acanthodians" which lived from the Early Devonian to the Early Permian. Members of the order have been found Cosmopolitan distribution, worldwide in ...

Palaeobiology

''Westrichus'' fed on small

crustaceans Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of Arthropod, arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquat ...

, and occasionally small fish, amphibians and even members of its own species.

References

{{Taxonbar, from=Q130349336 Prehistoric cartilaginous fish genera Acanthodiformes Fossil taxa described in 2003