''Pachycormus'' (from , 'thick' and 'trunk') is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of pachycormiform

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...

known from the Early

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

(

Toarcian The Toarcian is, in the International Commission on Stratigraphy, ICS' geologic timescale, an age (geology), age and stage (stratigraphy), stage in the Early Jurassic, Early or Lower Jurassic. It spans the time between 184.2 Megaannum, Ma (million ...

stage) of Europe.

Taxonomy

The type species ''P. macropterus'' was first named as a species of ''

Elops The Elopidae are a family (biology), family of ray-finned fish containing a single living genus ''Elops''. They are commonly known as ladyfish, skipjacks, jack-rashes, or tenpounders. The ladyfish are a coastal-dwelling fish found throughout t ...

'' by

Henri Marie Ducrotay de Blainville Henri Marie Ducrotay de Blainville (; 12 September 1777 – 1 May 1850) was a French zoologist and anatomist. Life Blainville was born at Arques-la-Bataille, Arques, near Dieppe, Seine-Maritime, Dieppe. As a young man, he went to Paris to study a ...

in 1818, it was placed into the newly named genus ''Pachycormus'' by

Louis Agassiz Jean Louis Rodolphe Agassiz ( ; ) FRS (For) FRSE (May 28, 1807 – December 14, 1873) was a Swiss-born American biologist and geologist who is recognized as a scholar of Earth's natural history. Spending his early life in Switzerland, he recei ...

in 1833. Fossils have been found in marine deposits from France, Germany and England. ''Pachycormus'' has recently been considered monotypic, only containing ''P.'' ''macropterus,'' with other species considered junior synonyms of the former, though this has subsequently been questioned. ''Pachycormus'' has generally been considered basal among Pachycormiformes, with a recent phylogeny finding it to be the second most basal pachycormiform after '' Euthynotus''.

Description

It grew up to 1 m (3.5 ft) in length. The teeth are short and designed for grasping. Its ecology has been interpreted as that of a generalist predator. Stomach contents indicate that its diet included

cephalopods A cephalopod is any member of the molluscan Taxonomic rank, class Cephalopoda (Greek language, Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral symm ...

(including vampyropods,

belemnites Belemnites may refer to: *Belemnitida, an extinct order of cephalopods commonly known as "belemnites" *Belemnites (genus), ''Belemnites'' (genus), a belemnite genus from the Early Jurassic {{disambiguation ...

and

ammonites Ammonoids are extinct, (typically) coiled-shelled cephalopods comprising the subclass Ammonoidea. They are more closely related to living octopuses, squid, and cuttlefish (which comprise the clade Coleoidea) than they are to nautiluses (family N ...

), and small fish, including juvenile ''Pachycormus''. One particular specimen shows that it died because of swallowing an ammonite too large for its size, and the ammonite itself was only shortly digested just before the fish's death.

References

* ''Fossils'' (Smithsonian Handbooks) by David Ward (page 214) Jurassic bony fish Prehistoric ray-finned fish genera Pachycormiformes Jurassic fish of Europe Taxa named by Louis Agassiz {{Jurassic-fish-stub