''Cheirothrix'' (meaning "hand hair") is an extinct genus of 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 ...

from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

. It is named for its enlarged pectoral fins, which show close convergence with modern

flying fish The Exocoetidae are a family (biology), family of Saltwater fish, marine Actinopterygii, ray-finned fish in the order (biology), order Beloniformes, known colloquially as flying fish or flying cod. About 64 species are grouped in seven genus, ge ...

Taxonomy

The following species are known: * †''C. guestphalicus'' (von der Marck & Schlüter, 1868) - Late

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 ...

of Germany (='' Telepholis biantennatus'' von der Marck, 1873, ''Megapus guestphalicus'' von der Marck & Schlüter, 1868) * †''C. lewisii''

Davis Davis may refer to: Places Antarctica * Mount Davis (Antarctica) * Davis Island (Palmer Archipelago) * Davis Station, an Australian base and research outpost in the Vestfold Hills * Davis Valley, Queen Elizabeth Land Canada * Davis, Sa ...

, 1887 - Late

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 ...

Lebanon Lebanon, officially the Republic of Lebanon, is a country in the Levant region of West Asia. Situated at the crossroads of the Mediterranean Basin and the Arabian Peninsula, it is bordered by Syria to the north and east, Israel to the south ...

(

Sahel Alma Sahel Alma () is a village located in the Keserwan District of the Keserwan-Jbeil Governorate in Lebanon, it constitutes along with three other villages (Sarba, Haret Sakher and Ghadir) the area known as Jounieh. Sahel Alma is situated between the ...

) * †''C. libanicus'' Pictet &

Humbert Humbert, Umbert or Humberto (Latinized ''Humbertus'') is a Germanic given name, from ''hun'' "warrior" and ''beraht'' "bright". It also came into use as a surname. Given name ;Royalty and Middle Ages * Emebert (died 710) * Humbert of Maroilles ...

, 1866 - Late Santonian of Lebanon (Sahel Alma) The fossilised remains of ''Cheirothrix lewisii'' were found in limestone strata in Lebanon dating back about 85 million years. This fish was first described by

James William Davis James William Davis (1846, Leeds-1893) was a British people, British Natural History, naturalist who specialised in fossil Evolution of fish, fish. He lived at Chevinedge, Halifax, West Yorkshire, Halifax in Yorkshire. James William Davis was a l ...

in 1887 and was named in honour of Professor E. R. Lewis of the American College in Beirut. Professor Lewis had originally found the fossil at Sahel Alma on

Mount Lebanon Mount Lebanon (, ; , ; ) is a mountain range in Lebanon. It is about long and averages above in elevation, with its peak at . The range provides a typical alpine climate year-round. Mount Lebanon is well-known for its snow-covered mountains, ...

. In this famous fossil location, about sixty species of fish have been found, none of them known from elsewhere in the world.

Description

''Cheirothrix'' is characterized by enormous

pectoral fins Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only b ...

and the ventral lobe of the tail fin is also much enlarged. It seems likely that these fish could launch themselves out of the water and glide hundreds of metres (yards) through the air, probably to evade

predators Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill ...

Distribution

During the Cretaceous period, sea levels were much higher than they are now. The fish remains at Sahel Alma are very well preserved. The rock is a fine-grained limestone found in an area much folded and faulted and is laid down in thick beds. The fish may have died because of a localized shortage of

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

. Five specimens of ''Cheirothrix lewisii'' were found, each preserved in such detail that the fifty or so

vertebrae Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spinal ...

can be counted and the branching rays of the pectoral fins can be seen clearly. The

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

is a cleft slab of limestone with remains of the fish on both sides. It is now kept in the

Natural History Museum A natural history museum or museum of natural history is a scientific institution with natural history scientific collection, collections that include current and historical records of animals, plants, Fungus, fungi, ecosystems, geology, paleo ...

in London. Another member of the genus, ''Cheirothrix libanicus'', is found in the same fossil bed and other members of the genus are known from 84-to-70-million-year-old deposits in Germany.

References

External links

Cheirothrix - Gnathostomata - Alepisauriformes
- The Paleobiology Database

† 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 ...

Prehistoric ray-finned fish genera Late Cretaceous fish of Asia Cretaceous fish of Europe Late Cretaceous bony fish Santonian genus first appearances Campanian genus extinctions Fossils of Germany Fossils of Lebanon Taxa named by François Jules Pictet de la Rive Fossil taxa described in 1866 {{Paleo-rayfinned-fish-stub