Chimaera

Chimaera

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Chimaeras are cartilaginous fish
Chondrichthyes
Chondrichthyes or cartilaginous fishes are jawed fish with paired fins, paired nares, scales, two-chambered hearts, and skeletons made of cartilage rather than bone...

 in the order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...

 Chimaeriformes, known informally as ghost sharks, ratfish (not to be confused with the rattail
Rattail
Grenadiers or rattails are generally large, brown to black gadiform marine fish of the family Macrouridae...

s), spookfish (not to be confused with the true spookfish
Barreleye
Barreleyes, also known as spook fish , are small deep-sea osmeriform fish comprising the family Opisthoproctidae...

 of the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Opisthoproctidae), or rabbitfishes (not to be confused with the true rabbitfish
Rabbitfish
Rabbitfishes or spinefoots are perciform fishes in the family Siganidae. The 28 species are in a single genus, Siganus. In some now obsolete classifications, the species having prominent face stripes—colloquially called foxfaces–are in the genus Lo. Other species like the Masked...

es of the family Siganidae). They may be the "oldest and most enigmatic groups of fishes alive today." At one time a "diverse and abundant" group (based on the fossil record), their closest living relatives are shark
Shark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....

s, though in evolutionary terms they branched off from sharks nearly 400 million years ago and have remained isolated ever since. Today they are largely confined to deep water.

Description and habits


Chimaeras live in temperate ocean floors down to 2600 metres (8,530.2 ft) depth, with few occurring at depths shallower than 200 metres (656.2 ft). Exceptions include the members of the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 Callorhinchus
Callorhinchus
The family Callorhincidae , or plough-nose chimaeras, are a family of marine fish. They are similar in form and habits to other chimaeras, but are distinguished by the presence of an elongated and flexible fleshy snout, with a vague resemblance to a ploughshare...

, the rabbit fish
Chimaera monstrosa
Chimaera monstrosa, also known as the rabbit fish or rat fish, is a species of fish in the Chimaeridae family.-Anatomy and appearance:...

 and the spotted ratfish
Spotted ratfish
The spotted ratfish, Hydrolagus colliei, is a chimaera found in the north-eastern Pacific Ocean. Often seen by divers at night in the Pacific Northwest, this harmless shark relative gets its characteristic name from a pointed rat-like tail. The ratfish lays leathery egg cases on the bottom of muddy...

, which locally/periodically can be found at relatively shallow depths. Consequently, these are also among the only species from the Chimaera order that are kept in public aquaria. They have elongated, soft bodies, with a bulky head and a single gill
Gill
A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...

-opening. They grow up to 150 centimetres (4.9 ft) in length, although this includes the lengthy tail found in some species. In many species, the snout is modified into an elongated sensory organ.

Like other members of the class Chondrichthyes
Chondrichthyes
Chondrichthyes or cartilaginous fishes are jawed fish with paired fins, paired nares, scales, two-chambered hearts, and skeletons made of cartilage rather than bone...

, chimaeras have a skeleton constructed of cartilage
Cartilage
Cartilage is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...

. Their skin is smooth and largely covered by placoid scales, and their color can range from black to brownish gray. For defense, most chimaeras have a venom
Venom
Venom is the general term referring to any variety of toxins used by certain types of animals that inject it into their victims by the means of a bite or a sting...

ous spine
Spine (zoology)
A spine is a hard, thorny or needle-like structure which occurs on various animals. Animals such as porcupines and sea urchins grow spines as a self-defense mechanism. Spines are often formed of keratin...

 located in front of the dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...

.

Chimaeras resemble sharks in some ways: they employ claspers for internal fertilization of females and they lay eggs
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...

 with leather
Leather
Leather is a durable and flexible material created via the tanning of putrescible animal rawhide and skin, primarily cattlehide. It can be produced through different manufacturing processes, ranging from cottage industry to heavy industry.-Forms:...

y cases. However, unlike sharks, male chimaeras also have retractable sexual appendages on the forehead (a type of tentaculum) and in front of the pelvic fins. The females lay eggs in spindle
Spindle (textiles)
A spindle is a wooden spike used for spinning wool, flax, hemp, cotton, and other fibres into thread. It is commonly weighted at either the bottom middle or top, most commonly by a circular or spherical object called a whorl, and may also have a hook, groove or notch, though spindles without...

-shaped leathery cases.

They also differ from sharks in that their upper jaws are fused with their skulls and they have separate anal and urogenital openings. They lack sharks' many sharp and replaceable teeth, having instead just three pairs of large permanent grinding tooth plates.They have gill cover or operculum
Operculum (fish)
The operculum of a bony fish is the hard bony flap covering and protecting the gills. In most fish, the rear edge of the operculum roughly marks the division between the head and the body....

 like bony fishes. Chimaera are the only vertebrates to retain traces of a third pair of limbs.

Classification


In some classifications the chimaeras are included (as subclass Holocephali) in the class Chondrichthyes
Chondrichthyes
Chondrichthyes or cartilaginous fishes are jawed fish with paired fins, paired nares, scales, two-chambered hearts, and skeletons made of cartilage rather than bone...

 of cartilaginous fishes; in other systems this distinction may be raised to the level of class. Chimaeras also have some characteristics of bony fishes
Osteichthyes
Osteichthyes , also called bony fish, are a taxonomic group of fish that have bony, as opposed to cartilaginous, skeletons. The vast majority of fish are osteichthyes, which is an extremely diverse and abundant group consisting of over 29,000 species...

.

A renewed effort to explore deep water and to undertake taxonomic analysis of specimens in museum collections led to a boom during the first decade of the 21st century in the number of new species identified. There are more than fifty extant species in six genera and three families
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 (an additional three genera and two families are only known from fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

s):

Family Callorhinchidae Garman, 1901
  • Genus Callorhinchus
    Callorhinchus
    The family Callorhincidae , or plough-nose chimaeras, are a family of marine fish. They are similar in form and habits to other chimaeras, but are distinguished by the presence of an elongated and flexible fleshy snout, with a vague resemblance to a ploughshare...

    Lacépède, 1798
    • Callorhinchus callorynchus
      Callorhinchus callorynchus
      The elephantfish is a species of fish in the Callorhinchidae family. It is found in Peru, Chile, Argentina, Uruguay and southern Brazil. Its natural habitat is open seas.-References:...

      (Linnaeus
      Carolus Linnaeus
      Carl Linnaeus , also known after his ennoblement as , was a Swedish botanist, physician, and zoologist, who laid the foundations for the modern scheme of binomial nomenclature. He is known as the father of modern taxonomy, and is also considered one of the fathers of modern ecology...

      , 1758)
      (Ploughnose chimaera)
    • Callorhinchus capensis A. H. A. Duméril, 1865 (Cape elephantfish)
    • Callorhinchus milii Bory de Saint-Vincent
      Jean Baptiste Bory de Saint-Vincent
      Jean Baptiste Bory de Saint-Vincent was a French naturalist. He was born at Agen...

      , 1823
      (Australian ghost shark)
  • Genus †Edaphodon
    Edaphodon
    Edaphodon was a prehistoric chimaeriforme fish genus belonging to the family callorhinchidae. Edaphodon was a type of rabbitfish, a cartilaginous fish related to sharks and rays, and indeed some rabbitfishes are still alive today. Edaphodon has under fifteen known species, all of which are extinct...

    -prehistoric
    • Edaphodon agassizi Buckland
      William Buckland
      The Very Rev. Dr William Buckland DD FRS was an English geologist, palaeontologist and Dean of Westminster, who wrote the first full account of a fossil dinosaur, which he named Megalosaurus...

      , 1835
    • Edaphodon antwerpiensis Leriche, 1926
    • Edaphodon bucklandi Agassiz
      Louis Agassiz
      Jean Louis Rodolphe Agassiz was a Swiss paleontologist, glaciologist, geologist and a prominent innovator in the study of the Earth's natural history. He grew up in Switzerland and became a professor of natural history at University of Neuchâtel...

      , 1843
    • Edaphodon eyrensis Long, 1985
    • Edaphodon kawai
      Edaphodon kawai
      Edaphodon kawai was a prehistoric chimaeriforme fish species belonging to the genus Edaphodon, of which all the species are now extinct. Edaphodon kawai was a type of rabbitfish, a cartilaginous fish related to sharks and rays, and indeed, some rabbitfishes are still alive today...

      Consoli, 2006
    • Edaphodon laqueatus Leidy
      Joseph Leidy
      Joseph Leidy was an American paleontologist.Leidy was professor of anatomy at the University of Pennsylvania, and later was a professor of natural history at Swarthmore College. His book Extinct Fauna of Dakota and Nebraska contained many species not previously described and many previously...

      , 1873
    • Edaphodon leptognathus - (has not been formally classified) Agassiz
      Louis Agassiz
      Jean Louis Rodolphe Agassiz was a Swiss paleontologist, glaciologist, geologist and a prominent innovator in the study of the Earth's natural history. He grew up in Switzerland and became a professor of natural history at University of Neuchâtel...

    • Edaphodon minor
    • Edaphodon mirabilis - (has not been formally classified)
    • Edaphodon mirificus Leidy
      Joseph Leidy
      Joseph Leidy was an American paleontologist.Leidy was professor of anatomy at the University of Pennsylvania, and later was a professor of natural history at Swarthmore College. His book Extinct Fauna of Dakota and Nebraska contained many species not previously described and many previously...

      , 1856
    • Edaphodon sedgwicki
    • Edaphodon smocki Cope
      Edward Drinker Cope
      Edward Drinker Cope was an American paleontologist and comparative anatomist, as well as a noted herpetologist and ichthyologist. Born to a wealthy Quaker family, Cope distinguished himself as a child prodigy interested in science; he published his first scientific paper at the age of nineteen...

    • Edaphodon stenobryus Cope
      Edward Drinker Cope
      Edward Drinker Cope was an American paleontologist and comparative anatomist, as well as a noted herpetologist and ichthyologist. Born to a wealthy Quaker family, Cope distinguished himself as a child prodigy interested in science; he published his first scientific paper at the age of nineteen...

    • Edaphodon tripartitus Cope
      Edward Drinker Cope
      Edward Drinker Cope was an American paleontologist and comparative anatomist, as well as a noted herpetologist and ichthyologist. Born to a wealthy Quaker family, Cope distinguished himself as a child prodigy interested in science; he published his first scientific paper at the age of nineteen...



Family Chimaeridae
Chimaeridae
The Chimaeridae, or shortnose chimaeras are a family of cartilaginous fish.They resemble other chimaeras in general form and habits, but have a short, rounded, snout, without the modifications found in related families. Many species have a long tapering tail, given them an alternative name of ratfish...

 Bonaparte
Charles Lucien Bonaparte
Charles Lucien Jules Laurent Bonaparte, 2nd Prince of Canino and Musignano was a French naturalist and ornithologist.-Biography:...

, 1831
  • Genus Chimaera
    Chimaera (genus)
    Chimaera is the type genus of the cartilaginous fish family Chimaeridae.It contains the following thirteen species with more likely to be discovered:** Chimaera argiloba Last, W. T...

    Linnaeus, 1758
    • Chimaera argiloba Last, W. T. White & Pogonoski, 2008 (Whitefin chimaera)
    • Chimaera bahamaensis Kemper, Ebert, Didier & Compagno, 2010 (Bahamas ghost shark)
    • Chimaera cubana Howell-Rivero
      Luis Howell-Rivero
      Luis Howell-Rivero was a Cuban biologist and anthropologist. In the 1920's and 30's he identified numerous new species of animals, especially fish, in Cuba and the rest of the Caribbean. One example is Squalus cubensis, the Cuban dogfish...

      , 1936
    • Chimaera fulva Didier, Last & W. T. White, 2008 (Southern Chimaera)
    • Chimaera jordani S. Tanaka (I)
      Shigeho Tanaka
      was a Japanese ichthyologist and professor of zoology at the Imperial University of Tokyo. He published numerous works on fishes and sharks and co-authored a book on Japanese fish with famous American scientist David Starr Jordan.Publications:...

      , 1905
      (Jordan's Chimaera)
    • Chimaera lignaria Didier, 2002 (Carpenter's chimaera)
    • Chimaera macrospina Didier, Last & W. T. White, 2008 (Longspine Chimaera)
    • Chimaera monstrosa
      Chimaera monstrosa
      Chimaera monstrosa, also known as the rabbit fish or rat fish, is a species of fish in the Chimaeridae family.-Anatomy and appearance:...

      Linnaeus
      Carolus Linnaeus
      Carl Linnaeus , also known after his ennoblement as , was a Swedish botanist, physician, and zoologist, who laid the foundations for the modern scheme of binomial nomenclature. He is known as the father of modern taxonomy, and is also considered one of the fathers of modern ecology...

      , 1758
      (Rabbit fish)
    • Chimaera notafricana Kemper, Ebert, Compagno & Didier, 2010 Cape Chimaera
    • Chimaera obscura Didier, Last & W. T. White, 2008 (Shortspine Chimaera)
    • Chimaera opalescens Luchetti, Iglésias & Sellos, 2011
    • Chimaera owstoni S. Tanaka (I)
      Shigeho Tanaka
      was a Japanese ichthyologist and professor of zoology at the Imperial University of Tokyo. He published numerous works on fishes and sharks and co-authored a book on Japanese fish with famous American scientist David Starr Jordan.Publications:...

      , 1905
      (Owston's Chimaera)
    • Chimaera panthera Didier, 1998 (Leopard Chimaera)
    • Chimaera phantasma Jordan
      David Starr Jordan
      David Starr Jordan, Ph.D., LL.D. was a leading eugenicist, ichthyologist, educator and peace activist. He was president of Indiana University and Stanford University.-Early life and education:...

       & Snyder
      John Otterbein Snyder
      John Otterbein Snyder was an American zoologist.As a student he met David Starr Jordan who inspired him to enter zoology. He eventually became a zoology instructor at Stanford University and served there from 1899 until 1943. He went on several major collecting expeditions aboard the USS Albatross...

      , 1900
      (Silver chimaera)

  • Genus Hydrolagus
    Hydrolagus
    Hydrolagus is a genus of fish in the Chimaeridae family.It contains the following species:* Hydrolagus affinis * Hydrolagus africanus...

    Gill
    Theodore Gill
    Theodore Nicholas Gill was an American ichthyologist, mammalogist, malacologist and librarian.Born and educated in New York City under private tutors, Gill early showed interest in natural history. He was associated with J...

    , 1863
    • Hydrolagus affinis (Brito Capello, 1868) (Smalleyed rabbitfish)
    • Hydrolagus africanus (Gilchrist, 1922) (African chimaera)
    • Hydrolagus alberti Bigelow
      Henry Bryant Bigelow
      Henry Bryant Bigelow was an American oceanographer and marine biologist.After graduating from Harvard in 1901, he began working with famed ichthyologist Alexander Agassiz. Bigelow accompanied Agassiz on several major marine science expeditions including one aboard the Albatross in 1907...

       & Schroeder
      William Charles Schroeder
      William Charles Schroeder was an American ichthyologist. He was born on Staten Island, New York. He, along with his lifelong colleague Henry Bryant Bigelow, made substantial contributions to the knowledge of the fish fauna of the western North Atlantic...

      , 1951
    • Hydrolagus alphus Quaranta, Didier, Long & Ebert, 2006
    • Hydrolagus barbouri (Garman, 1908)
    • Hydrolagus bemisi Didier, 2002 (Pale ghost shark)
    • Hydrolagus colliei (Lay
      George Tradescant Lay
      George Tradescant Lay was a British naturalist, missionary and diplomat.Lay was a naturalist on the English sailing ship HMS Blossom under the command of Captain Frederick William Beechey from 1825 to 1828, where he collected specimens in the Pacific including California, Alaska, Kamchatka, China,...

       & E. T. Bennett
      Edward Turner Bennett
      Edward Turner Bennett was an English zoologist and writer. He was the elder brother of the botanist John Joseph Bennett. Bennett was born at Hackney and practiced as a surgeon, but his chief pursuit was always zoology...

      , 1839)
      (Spotted ratfish)
    • Hydrolagus deani (H. M. Smith
      Hugh McCormick Smith
      Hugh McCormick Smith was an American ichthyologist and administrator in the Bureau of Fisheries.-Biography:...

       & Radcliffe
      Lewis Radcliffe
      Lewis Radcliffe was a naturalist, malacologist, and ichthyologist. He was Deputy Commissioner of the United States Bureau of Fisheries until 1932 and was the assistant naturalist under Hugh McCormick Smith for the 1907-1910 Philippines Expedition. During his life, he described numerous new species...

      , 1912)
      (Philippine chimaera)
    • Hydrolagus eidolon (Jordan
      David Starr Jordan
      David Starr Jordan, Ph.D., LL.D. was a leading eugenicist, ichthyologist, educator and peace activist. He was president of Indiana University and Stanford University.-Early life and education:...

       & Hubbs
      Carl Leavitt Hubbs
      -Youth:He was born in Williams, Arizona. He was the son of Charles Leavitt and Elizabeth Hubbs. His father had a wide variety of jobs . The family moved several times before settling in San Diego where he got his first taste of natural history...

      , 1925)
    • Hydrolagus homonycteris Didier, 2008 (Black Ghostshark)
    • Hydrolagus lemures (Whitley
      Gilbert Percy Whitley
      Gilbert Percy Whitley was a British-born Australian ichthyologist and malacologist who was Curator of Fishes at the Australian Museum in Sydney for about 40 years. He was born at Swaythling, Southampton, England, and was educated at King Edward VI School, Southampton and Osborne House...

      , 1939)
      (Blackfin ghostshark)
    • Hydrolagus lusitanicus Moura, Figueiredo, Bordalo-Machado, Almeida & Gordo, 2005
    • Hydrolagus macrophthalmus de Buen
      Don Fernando de Buen y Lozano
      Don Fernando de Buen y Lozano was a Spanish ichthyologist and oceanographer. He lived in Mexico, Uruguay, and Chile. In Uruguay, he was the director of the Department of Science at the Oceanography and Fisheries Service as well as Professor of Hydrobiology and Protozoology in the Faculty of Arts...

      , 1959
    • Hydrolagus marmoratus Didier, 2008 Marbled Ghostshark
    • Hydrolagus matallanasi
      Hydrolagus matallanasi
      Hydrolagus matallanasi is a species of very rare deep-water chimaera that lives in the ocean at depths of up to 600 m. The species is 150 million years old. It was discovered in 2001 by a team of Brazilian scientists....

      Soto & Vooren, 2004 (Striped rabbitfish)
    • Hydrolagus mccoskeri Barnett, Didier, Long & Ebert, 2006 (Galápagos Ghostshark)
    • Hydrolagus melanophasma K. C. James, Ebert, Long & Didier, 2009 (Eastern Pacific Black Ghostshark)
    • Hydrolagus mirabilis (Collett
      Robert Collett
      Robert Collett was a Norwegian zoologist. He worked with vertebrates, primarily fishes. From 1864 he was curator at the Zoological Museum in Oslo. In 1882 he became its director and from 1884 was a professor there...

      , 1904)
      (Large-eyed rabbitfish)
    • Hydrolagus mitsukurii
      Hydrolagus mitsukurii
      Hydrolagus mitsukurii is a species of fish in the Chimaeridae family. It is found in China, Japan, South Korea, the Philippines, Taiwan, and possibly Indonesia. Its natural habitat is open seas. It is threatened by habitat loss.-Source:...

      (Jordan
      David Starr Jordan
      David Starr Jordan, Ph.D., LL.D. was a leading eugenicist, ichthyologist, educator and peace activist. He was president of Indiana University and Stanford University.-Early life and education:...

       & Snyder
      John Otterbein Snyder
      John Otterbein Snyder was an American zoologist.As a student he met David Starr Jordan who inspired him to enter zoology. He eventually became a zoology instructor at Stanford University and served there from 1899 until 1943. He went on several major collecting expeditions aboard the USS Albatross...

      , 1904)
      (Spookfish)
    • Hydrolagus novaezealandiae (Fowler
      Henry Weed Fowler
      Henry Weed Fowler was an American zoologist born in Holmesburg, Pennsylvania.He studied at Stanford University under David Starr Jordan...

      , 1911)
      (Dark ghostshark)
    • Hydrolagus ogilbyi (Waite
      Edgar Ravenswood Waite
      Edgar Ravenswood Waite was a British/Australian ichthyologist, ornithologist and zoologist.Waite was born in Leeds, Yorkshire, England, the second son of John Waite, a bank clerk,...

      , 1898)
    • Hydrolagus pallidus Hardy & Stehmann, 1990
    • Hydrolagus purpurescens (Gilbert
      Charles Henry Gilbert
      Charles Henry Gilbert was a pioneer ichthyologist and fishery biologist of particular significance to natural history of the western United States. He collected and studied fishes from Central America north to Alaska and described many new species...

      , 1905)
      (Purple chimaera)
    • Hydrolagus trolli Didier & Séret, 2002 (Pointy-nosed blue chimaera)
    • Hydrolagus waitei Fowler
      Henry Weed Fowler
      Henry Weed Fowler was an American zoologist born in Holmesburg, Pennsylvania.He studied at Stanford University under David Starr Jordan...

      , 1907
    • Hydrolagus sp. D/G Giant Black Chimaera
    • Hydrolagus sp. F Peruvian Ratfish

Family Rhinochimaeridae
Rhinochimaeridae
Rhinochimaeridae, commonly known as long-nosed chimaeras, is a family of cartilaginous fish. They are similar in form and habits to other chimaeras, but have an exceptionally long, conical or paddle-shaped, snout. The snout has numerous sensory nerve endings, and is used to find food such as small...

 Garman, 1901
  • Genus Harriotta
    Harriotta
    Harriotta is a genus of fish in the Rhinochimaeridae family.It contains the following species:* Harriotta haeckeli Karrer, 1972 * Harriotta raleighana Goode & Bean, 1895...

    Goode
    George Brown Goode
    George Brown Goode , was an ichthyologist, although most of his time was spent as a museum administrator and he was very interested in the history of science, especially the history of the development of science in America. Goode graduated from Wesleyan University and studied at Harvard University...

     & Bean
    Tarleton Hoffman Bean
    Tarleton Hoffman Bean was an American ichthyologist, born at Bainbridge, Pennsylvania on 8 October 1846. He died in Albany, New York on 28 December 1916.-FAMILY AND EDUCATION :...

    , 1895
    • Harriotta haeckeli Karrer, 1972 (Smallspine spookfish)
    • Harriotta raleighana Goode
      George Brown Goode
      George Brown Goode , was an ichthyologist, although most of his time was spent as a museum administrator and he was very interested in the history of science, especially the history of the development of science in America. Goode graduated from Wesleyan University and studied at Harvard University...

       & Bean
      Tarleton Hoffman Bean
      Tarleton Hoffman Bean was an American ichthyologist, born at Bainbridge, Pennsylvania on 8 October 1846. He died in Albany, New York on 28 December 1916.-FAMILY AND EDUCATION :...

      , 1895
      (Pacific Longnose chimaera)
  • Genus Neoharriotta
    Neoharriotta
    Neoharriotta is a genus of fish in the Rhinochimaeridae family.It contains the following species:* Neoharriotta carri Bullis & J. S. Carpenter, 1966* Neoharriotta pinnata...

    Bigelow
    Henry Bryant Bigelow
    Henry Bryant Bigelow was an American oceanographer and marine biologist.After graduating from Harvard in 1901, he began working with famed ichthyologist Alexander Agassiz. Bigelow accompanied Agassiz on several major marine science expeditions including one aboard the Albatross in 1907...

     & Schroeder
    William Charles Schroeder
    William Charles Schroeder was an American ichthyologist. He was born on Staten Island, New York. He, along with his lifelong colleague Henry Bryant Bigelow, made substantial contributions to the knowledge of the fish fauna of the western North Atlantic...

    , 1950
    • Neoharriotta carri Bullis & J. S. Carpenter, 1966
    • Neoharriotta pinnata (Schnakenbeck, 1931) (Sicklefin chimaera)
    • Neoharriotta pumila Didier & Stehmann, 1996
  • Genus Rhinochimaera
    Rhinochimaera
    Rhinochimaera is a genus of fish in the Rhinochimaeridae family.It contains the following species:* Rhinochimaera africana Compagno, Stehmann & Ebert, 1990* Rhinochimaera atlantica Holt & Byrne, 1909...

    Garman, 1901
    • Rhinochimaera africana Compagno, Stehmann & Ebert, 1990
    • Rhinochimaera atlantica Holt
      Ernest William Lyons Holt
      Ernest William Lyons Holt was an eminent English marine naturalist and biologist specialized in ichthyology, the study of fish...

       & Byrne, 1909
      (Straightnose rabbitfish)
    • Rhinochimaera pacifica (Mitsukuri
      Kakichi Mitsukuri
      was a Japanese zoölogist, born at Edo. In 1873 he came to the United States, where he received the Ph.D. degree from Yale in 1879 and from Johns Hopkins in 1883. He was appointed professor in the college of science of the Imperial University of Tokyo in 1882 and councilor of the university in 1893...

      , 1895)
      (Pacific spookfish)

Family †Squalorajidae
  • Genus Squaloraja
    Squaloraja
    Squaloraja is a genus of fish in the extinct Squalorajidae family....

    Agassiz, 1836

Family †Echinochimaeridae
  • Genus Echinochimaera
    Echinochimaera
    Echinochimaera is an extinct genus of fish, it was assigned to the order chimaera by Jack Sepkoski in 2002. The genus' name derives from the Greek εχινό meaning spiny, and chimaera.-Species:...

    Lund, 1977
    • Echinochimaera meltoni Lund, 1977
    • Echinochimaera snyderi Lund, 1988

Phylogenetics


The evolution of these species has been problematic given the paucity of good fossils. DNA sequences have become the preferred approach to understanding speciation.

The order appears to have originated about 420 million years ago during the Silurian
Silurian
The Silurian is a geologic period and system that extends from the end of the Ordovician Period, about 443.7 ± 1.5 Mya , to the beginning of the Devonian Period, about 416.0 ± 2.8 Mya . As with other geologic periods, the rock beds that define the period's start and end are well identified, but the...

. The 39 extant species fall into three families - the callorhinchids, rhinochimaerids and chimaerids) with the callorhinchids being the most basal clade. The families appear to have diverged during the late Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to  Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...

 to early Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...

 (170-120 MYA.)