''Coelacanthus'' ("Hollow Spine") is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of extinct

coelacanth The coelacanths ( ) are fish belonging to the order Actinistia that includes two extant species in the genus ''Latimeria'': the West Indian Ocean coelacanth (''Latimeria chalumnae''), primarily found near the Comoro Islands off the east coast ...

s that first appeared during the

Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...

period. It was the first

of coelacanths described, about a

century A century is a period of 100 years. Centuries are numbered ordinally in English and many other languages. The word ''century'' comes from the Latin ''centum'', meaning ''one hundred''. ''Century'' is sometimes abbreviated as c. A centennial or ...

before the discovery of the extant coelacanth. The order

Coelacanthiformes The coelacanths ( ) are fish belonging to the order Actinistia that includes two extant species in the genus ''Latimeria'': the West Indian Ocean coelacanth (''Latimeria chalumnae''), primarily found near the Comoro Islands off the east coast ...

is named after it.

Description

''Coelacanthus'' bears a superficial similarity to the living

Latimeria ''Latimeria'' is a rare genus of fish which contains the only living species of coelacanth. It includes two Extant taxon, extant species: the West Indian Ocean coelacanth (''Latimeria chalumnae'') and the Indonesian coelacanth (''Latimeria menado ...

'', though it was smaller, and had a more elongated head. Individuals grew up to in length, had an elongate codavypter or supplementary tail lobe, and had small lobed fins, suggesting that ''Coelacanthus'' were open-water predators. The fin rays of the

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

are hollow, which gave ''Coelacanthus'' its name. The name is an adaptation of the Modern Latin cœlacanthus ("hollow spine"), from the Greek κοῖλ-ος (koilos; "hollow") and ἄκανθ-α (akantha; "spine"). These hollow spines are a typical feature of coelacanths. Coelacanthus_granulatus_restoration

Distribution and time

The

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

''Coelacanthus granulatus'' was described from the

late Permian Late may refer to: * LATE, an acronym which could stand for: ** Limbic-predominant age-related TDP-43 encephalopathy, a proposed form of dementia ** Local-authority trading enterprise, a New Zealand business law ** Local average treatment effect, ...

(

Wuchiapingian In the geologic timescale, the Wuchiapingian or Wujiapingian (from in the Liangshan area of Hanzhong, Shaanxi Province) is an age or stage of the Permian. It is also the lower or earlier of two subdivisions of the Lopingian Epoch or Series. The ...

) Kupferschiefer of Germany and equivalent

Marl Slate The Marl Slate Formation is a geological formation in England. Despite its name, it is mostly dolomite rock. The Marl Slate Formation was formed about 273 to 259 million years ago, during the Guadalupian and Lopingian epochs of the late Permian ...

of England. ''Coelacanthus'' is primarily known from Late Permian and Early Triassic deposits in Europe and Canada, although the referred species ''C. welleri'', known from Iowa, is of Late Devonian (

Famennian The Famennian is the latter of two faunal stages in the Late Devonian Epoch. The most recent estimate for its duration estimates that it lasted from around 371.1 million years ago to 359.3 million years ago. An earlier 2012 estimate, still used b ...

) age. It survived the

Permian–Triassic extinction event The Permian–Triassic (P–T, P–Tr) extinction event, also known as the Latest Permian extinction event, the End-Permian Extinction and colloquially as the Great Dying, formed the boundary between the Permian and Triassic geologic periods, as ...

, and one species, ''C. banffensis'', is known from the Early Triassic. Several other species that were first referred to ''Coelacanthus'' were later reallocated to other genera. ''Coelacanthus minor'' was considered by Woodward (1891) as potentially belonging to the Triassic genus ''

Heptanema ''Heptanema'' is an Extinction, extinct genus of prehistoric coelacanth from the Middle Triassic (Ladinian) of northern Italy and Switzerland. The Type species, type and only species is ''Heptanema paradoxum''. Woodward (1891) suggested that '' ...

'', while Martin and Wenz (1984) considered ''Coelacanthus lunzensis'' a possible synonym of ''

Garnbergia ''Garnbergia'' is an extinct genus of prehistoric bony fish that lived during the Anisian stage of the Middle Triassic epoch. See also * Prehistoric fish The evolution of fish began about 530 million years ago during the Cambrian explosi ...

''. ''Coelacanthus madagascariensis'' from the Early Triassic of Madagascar was reattributed to the genus ''

Rhabdoderma ''Rhabdoderma'' is an extinct genus of coelacanth fish in the class Sarcopterygii. It lived in the Carboniferous and Early Triassic, and its fossils have been found in Europe, Madagascar and North America. Species * ''Rhabdoderma alderingi'' ...

'', and ''Coelacanthus evolutus'' is a synonym of '' Whiteia woodwardi''.Forey P. L. (1998) History of the coelacanth fishes (Chapman & Hall, London).

References

External links

Mikko's Phylogeny Archive o
Coelacanthiformes
Coelacanthidae Prehistoric lobe-finned fish genera Permian bony fish Triassic bony fish Triassic extinctions Prehistoric fish of Europe Prehistoric fish of North America Fossil taxa described in 1836 Taxa named by Louis Agassiz {{paleo-lobefinned-fish-stub