Dorsetichthys is an extinct genus of marine stem-teleost ray-finned fish from the Early Jurassic period of Europe. It contains a single species, D. bechei, known from the Sinemurian-aged Lower Lias of England and the Moltrasio Formation of Italy.

Description

Dorsetichthys was an elongated teleost that could reach up to 20 centimetres (7.9 in) long. This fish had ganoid scales close to modern gars.

Taxonomy

The type species of Dorsetichthys, D. bechei, was formerly assigned to Pholidophorus, but Arratia (2013) recognized it as generically distinct from the Pholidophorus type species, placing it in the new family Dorsetichthyidae and new order Dorsetichthyiformes.

Dorsetichthys is widely considered to be a teleosteomorph, a primitive early relative of teleosts, the group that comprises the vast majority of living ray-finned fish. Cladogram of Teleosteomorpha after Sferco et al. 2021:

Holostei
Teleostei total group (Teleosteomorpha)Pachycormiformes Aspidorhynchiformes Mesturus Pholidophoridae Siemensichythys Dorsetichthys Eurycormus Leptolepidae Luisiellidae Tharsis dubius Varasichthyidae Ascalabos Ichthyodectiformes Teleostei crown group (including Crossognathiformes)
Pachycormiformes
Aspidorhynchiformes Mesturus Pholidophoridae Siemensichythys Dorsetichthys Eurycormus Leptolepidae Luisiellidae Tharsis dubius Varasichthyidae Ascalabos Ichthyodectiformes Teleostei crown group (including Crossognathiformes)
Aspidorhynchiformes
Mesturus
Pholidophoridae Siemensichythys Dorsetichthys Eurycormus Leptolepidae Luisiellidae Tharsis dubius Varasichthyidae Ascalabos Ichthyodectiformes Teleostei crown group (including Crossognathiformes)
Pholidophoridae
Siemensichythys Dorsetichthys Eurycormus Leptolepidae Luisiellidae Tharsis dubius Varasichthyidae Ascalabos Ichthyodectiformes Teleostei crown group (including Crossognathiformes)
Siemensichythys
Dorsetichthys Eurycormus Leptolepidae Luisiellidae Tharsis dubius Varasichthyidae Ascalabos Ichthyodectiformes Teleostei crown group (including Crossognathiformes)
Dorsetichthys
Eurycormus Leptolepidae Luisiellidae Tharsis dubius Varasichthyidae Ascalabos Ichthyodectiformes Teleostei crown group (including Crossognathiformes)
Eurycormus
Leptolepidae Luisiellidae Tharsis dubius Varasichthyidae Ascalabos Ichthyodectiformes Teleostei crown group (including Crossognathiformes)
Leptolepidae
Luisiellidae Tharsis dubius Varasichthyidae Ascalabos Ichthyodectiformes Teleostei crown group (including Crossognathiformes)
Luisiellidae
Tharsis dubius Varasichthyidae Ascalabos Ichthyodectiformes Teleostei crown group (including Crossognathiformes)
Tharsis dubius
Varasichthyidae Ascalabos Ichthyodectiformes Teleostei crown group (including Crossognathiformes)
Varasichthyidae
Ascalabos Ichthyodectiformes Teleostei crown group (including Crossognathiformes)
Ascalabos
Ichthyodectiformes Teleostei crown group (including Crossognathiformes)
Ichthyodectiformes
Teleostei crown group (including Crossognathiformes)

Ecology

One probable specimen of Dorsetichthys has been found preserved within the jaws of the larger fish Dapedium punctatum suggesting that it was preyed upon by the larger fish.