Cheirothricidae is a family of extinct marine

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 ...

, perhaps belonging to the

Aulopiformes Aulopiformes is a diverse order (biology), order of Marine (ocean), marine ray-finned fish consisting of some 15 Extant taxon, extant and several prehistoric family (biology), families with about 45 genera and over 230 species. The common names ...

, although they are tentatively placed as indeterminate eurypterygians. They lived during the Upper

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

(

Cenomanian The Cenomanian is, in the International Commission on Stratigraphy's (ICS) geological timescale, the oldest or earliest age (geology), age of the Late Cretaceous epoch (geology), Epoch or the lowest stage (stratigraphy), stage of the Upper Cretace ...

Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...

, about 95 - 71 million years ago) and their fossil remains are found in the Middle East and Europe. They were characterized by very expanded even fins.

Genera

*†'' Cheirothrix'' Pictet and Humbert, 1866 - Late Santonian to Campanian of Germany and Lebanon *†'' Exocoetoides'' Davis, 1887 - Late Cenomanian of Lebanon *?†'' Telepholis'' von der Marck, 1868 - Late Campanian of Germany (possibly a stem- stomiiform)

Description

The main characteristic of these small fish (the length of the body was usually between 3 and 20 centimeters in length) was given by the extreme development of the even fins; in '' Cheirothrix'' species the pectoral fins were particularly developed, while in '' Telepholis'' and '' Exocoetoides'' also the pelvic fins were large. In any case, the fins were large and provided with very long rays. ''Cheirothrix'' was the largest genus, had a more robust body and could reach 20 centimeters in length; ''Telepholis'', usually shorter and with a thinner body, had shorter pectoral fins than ''Exocoetoides'' and had some small and thin shields in the dorsal region, rounded or polygonal, adorned in the center with a tubercle. The caudal fin was not very indented. However, ''Telepholis'' may not be a cheirothricid. ''Exocoetoides'', on the other hand, was decidedly small in size (between 3 and 7 centimeters in length) and the pectoral fins were particularly long (they could reach the anal region); in the caudal fin both lobes were the same size.

Taxonomy and fossil record

Established in 1901 by

Arthur Smith Woodward Sir Arthur Smith Woodward, FRS (23 May 1864 – 2 September 1944) was an English palaeontologist, known as a world expert in fossil fish. He also described the Piltdown Man fossils, which were later determined to be fraudulent. He is not rel ...

, the family Cheirothricidae was widespread in the ancient

Tethys Ocean The Tethys Ocean ( ; ), also called the Tethys Sea or the Neo-Tethys, was a prehistoric ocean during much of the Mesozoic Era and early-mid Cenozoic Era. It was the predecessor to the modern Indian Ocean, the Mediterranean Sea, and the Eurasia ...

, in the areas currently occupied by the Middle East and Europe. Two genera are known in the

of Lebanon (''Cheirothrix'' in deposits of the

Santonian The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya ( million years ago) and 83.6 ± 0.7 m ...

, and ''Exocoetoides'' from the

), and in Germany (''Cheirothrix'' and ''Telepholis'' from the Campanian). Members of this family are generally considered to be representatives of the

; in particular, affinities have been proposed with the extinct group of Enchodontidae. However, a 2009 study found them to be indeterminate members of the Eurypterygii.

Paleobiology

The Cheirothricidae had a morphology remarkably similar to that of the extant flying fishes and to that of other extinct forms like '' Thoracopterus''. Like today's ''

Cypselurus ''Cypselurus'' is a genus of flying fish in the family Exocoetidae. They are found across Indo-Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific ...

'' and ''

Exocoetus ''Exocoetus'' is a genus of flying fishes. It is a bony fish. The body is covered with cycloid scales. The mouth is wide, and the jaws bear teeth. It is a marine fish. The tail has hypobatic fins as the ventral lobe. Species Five species in th ...

'', Cheirothricidae were also likely to perform a sort of gliding flight over water, thanks to the notable expansion of the pectoral and pelvic fins.

Bibliography

* James W. Davis (1887)
"The fossil fishes of the chalk of Mount Lebanon in Syria".
Royal Dublin Society. 2 (3). *M. Gayet, A. Belouze & P. Abi Saad, 2003. Les Poissons fossiles. Éditions Desiris,. 158 p.

References

Note: This article has been expanded using material based on a translation of an article from the Italian Wikipedia. {{Taxonbar, from=Q30895919

† A dagger, obelisk, or obelus is a typographical mark that usually indicates a footnote if an asterisk has already been used. The symbol is also used to indicate death (of people) or extinction (of species or languages). It is one of the mo ...

Cenomanian first appearances Campanian extinctions