''Isurus'' (meaning "equal tail") is a

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 ...

mackerel shark The Lamniformes (, from Greek ''lamna'' "fish of prey") are an order of sharks commonly known as mackerel sharks (which may also refer specifically to the family Lamnidae). It includes some of the most familiar species of sharks, such as the g ...

s in the family

Lamnidae The Lamnidae are the family of mackerel sharks known as white sharks. They are large, fast-swimming predatory fish found in oceans worldwide, though they prefer environments with colder water. The name of the family is formed from the Greek word ...

, commonly known as the mako sharks. They are largely pelagic, and are fast, predatory fish capable of swimming at speeds of up to .

Fossil history and evolution

Although fossil teeth of ''Isurus'' have been reported from as early as 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 ...

, they are likely to be of a shark with a similar dentition, '' Cretoxyrhina''; since at one point they were considered to be the same (now defunct) genus ''Oxyrhina'', and modern referrals to ''Isurus'' in the Cretaceous are scant. The earliest appearance of ''Isurus'' proper seems to be during the

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

with ''Isurus desori''. There has been much debate and speculation about the evolutionary origin and relationships between ''Isurus'' and its closest relatives, including the extant

great white shark The great white shark (''Carcharodon carcharias''), also known as the white shark, white pointer, or simply great white, is a species of large Lamniformes, mackerel shark which can be found in the coastal surface waters of all the major ocea ...

(''Carcharodon carcharias''). Molecular clock analyses place the last common ancestor of ''Isurus'' and '' Carcharodon'' between 43–60 million years ago during the Late Paleocene-Early Eocene. This insight should guide efforts to better resolve the fossil ancestry of both lineages, by providing a window of time in which to search for ancestor candidates. Many fossil species of Lamnids have historically been placed under ''Isurus'', which are now largely considered separate genera. These include species of ''Carcharodon'' (''Cosmopolitodus'') like ''C. hastalis, C. planus'', species of ''Macrorhizodus,'' ''Isurolamna'', and others.

Description

The two living species are the shortfin mako shark (''I. oxyrinchus'') and the

longfin mako shark The longfin mako shark (''Isurus paucus'') is a species of mackerel shark in the family Lamnidae, with a probable worldwide distribution in temperate and tropical waters. An uncommon species, it is typically lumped together under the name "mako" ...

(''I. paucus''). They range in length from , and have an approximate maximum weight of . They both have a distinctive blue-gray color scheme common among mackerel sharks.

Species

The genus contains these species: * '' Isurus oxyrinchus'' (

Rafinesque Constantine Samuel Rafinesque-Schmaltz (; 22 October 178318 September 1840) was a French early 19th-century polymath born near Constantinople in the Ottoman Empire and self-educated in France. He traveled as a young man in the United States, ult ...

, 1810) (shortfin mako shark) * '' Isurus paucus'' ( Guitart-Manday, 1966) (longfin mako shark)Tony Ayling & Geoffrey Cox, ''Collins Guide to the Sea Fishes of New Zealand'', William Collins Publishers Ltd, Auckland, New Zealand 1982 *†''

Isurus desori ''Isurus desori'' or "Desori shark", or "Desori mako shark" is an extinct species of Mako shark, that lived in the Oligocene and Middle Miocene, between 34 and 11 million years ago. It measured long. Diet The ''Isurus desori'' hunted squids ...

'' (

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 ...

, 1843) *†''

Isurus retroflexus ''Isurus'' (meaning "equal tail") is a genus of mackerel sharks in the family Lamnidae, commonly known as the mako sharks. They are largely pelagic, and are fast, predatory fish capable of swimming at speeds of up to . Fossil history and evolu ...

'' (

, 1843)

References

{{Authority control Extant Late Cretaceous first appearances Shark genera Taxa named by Constantine Samuel Rafinesque Taxa described in 1810

Fossil history and evolution

Description

Species

See also

References