Gebrayelichthyidae is a

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

pycnodontid Pycnodontidae is an extinct family of ray-finned fishes, ranging from the Triassic period until the Eocene. Genera * '' Acrotemnus'' Agassiz, 1843 * '' Anomoeodus'' Forir, 1887 * ''Athrodon'' Sauvage, 1880 * '' Callodus'' Thurmond, 1974 * '' Coc ...

fish, with a superficially

shrimpfish Shrimpfish, also called razorfish, are five small species of marine fishes in the subfamily Centriscinae of the family Centriscidae. The species in the genera ''Aeoliscus'' and ''Centriscus'' are found in relatively shallow tropical parts of the ...

-like appearance that lived during the lower

Cenomanian The Cenomanian is, in the ICS' geological timescale, the oldest or earliest age of the Late Cretaceous Epoch or the lowest stage of the Upper Cretaceous Series. An age is a unit of geochronology; it is a unit of time; the stage is a unit in the s ...

. The family is composed of two genera, the

type genus In biological taxonomy, the type genus is the genus which defines a biological family and the root of the family name. Zoological nomenclature According to the International Code of Zoological Nomenclature, "The name-bearing type of a nominal f ...

, '' Gebrayelichthys'', and the

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

'' Maraldichthys''. The Gebrayelichthyids are highly modified in appearance, having their bodies compressed and vertebrae elongated. Gebrayelichthyidae, together with Gladiopycnodontidae and Coccodontidae, make up the pycnodontid superfamily Coccodontoidea. Maraldichthys verticalis

Description

''Gebrayelichthys'' was strongly flattened on the sides. The body height was 1.8 to 2 times the body length. The head and torso each made up half of the total length. The skull was similar to that of other

Pycnodontiformes Pycnodontiformes is an extinct order of primarily marine bony fish. The group first appeared during the Late Triassic and disappeared during the Eocene. The group has been found in rock formations in Africa, Asia, Europe, North and South America ...

. The orbit was high up under the curved head profile, the muzzle was long and directed downwards. There were a few pointed teeth on the ploughshare. The anatomy of the lower jaw is unknown due to the lack of evidence. Behind the skull was a tall bone mast that supported a narrow, high ridge. Throughout the fleshy part of the ridge there were fins carrier (Pterygiophoren). Behind the lower jaw began a deep, laterally flattened abdominal keel, which was also supported in front by a thick, bony stem and was covered at the sides by bone plates. The keel of the abdomen reached as far as the crest of the back. The trailing edge of the abdominal keel was protected by plate-shaped scales, each with a short, thick spike. Most of the entrails were in the keel of the abdomen. At the front part of the belly keel the flashy lay cloaca. The pelvic fins stood on the leading edge of the keel, the pectoral fins about two-thirds of the way up on the keel. A caudal fin is not preserved in any fossil. There is still a

notochord In anatomy, the notochord is a flexible rod which is similar in structure to the stiffer cartilage. If a species has a notochord at any stage of its life cycle (along with 4 other features), it is, by definition, a chordate. The notochord consis ...

in the spine. The scales are small and limited to the axis of the body and the base of the back crest. ''Gebrayelichthys'' was probably a pelagic fish that ate plankton and small nectonic animals.

References

Pycnodontiformes Late Cretaceous fish Cretaceous bony fish Prehistoric ray-finned fish families Cenomanian first appearances Cenomanian extinctions {{Cretaceous-fish-stub

Description

Further reading

References