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Elasmobranchii Holocephali

Chondrichthyes
Chondrichthyes
(/kɒnˈdrɪkθɪ.iːz/; from Greek χονδρ- chondr- 'cartilage', ἰχθύς ichthys 'fish') is a class that contains the cartilaginous fishes: they are jawed vertebrates with paired fins, paired nares, scales, a heart with its chambers in series, and skeletons made of cartilage rather than bone. The class is divided into two subclasses: Elasmobranchii
Elasmobranchii
(sharks, rays, skates, and sawfish) and Holocephali
Holocephali
(chimaeras, sometimes called ghost sharks, which are sometimes separated into their own class). Within the infraphylum Gnathostomata, cartilaginous fishes are distinct from all other jawed vertebrates.

Contents

1 Anatomy

1.1 Skeleton 1.2 Appendages 1.3 Body covering 1.4 Respiratory system 1.5 Immune system

2 Reproduction 3 Classification 4 Evolution 5 Phylogeny 6 See also 7 References 8 Further reading

Anatomy[edit] See also: Cartilaginous versus bony fishes Skeleton[edit] The skeleton is cartilaginous. The notochord, which is present in the young, is gradually replaced by cartilage. Chondrichthyans also lack ribs, so if they leave water, the larger species' own body weight would crush their internal organs long before they would suffocate.[citation needed] As they do not have bone marrow, red blood cells are produced in the spleen and the epigonal organ (special tissue around the gonads, which is also thought to play a role in the immune system). They are also produced in the Leydig's organ, which is only found in certain cartilaginous fishes. The subclass Holocephali, which is a very specialized group, lacks both the Leydig's and epigonal organs. Appendages[edit] Apart from electric rays, which have a thick and flabby body, with soft, loose skin, chondrichthyans have tough skin covered with dermal teeth (again, Holocephali
Holocephali
is an exception, as the teeth are lost in adults, only kept on the clasping organ seen on the caudal ventral surface of the male), also called placoid scales (or dermal denticles), making it feel like sandpaper. In most species, all dermal denticles are oriented in one direction, making the skin feel very smooth if rubbed in one direction and very rough if rubbed in the other. Originally, the pectoral and pelvic girdles, which do not contain any dermal elements, did not connect. In later forms, each pair of fins became ventrally connected in the middle when scapulocoracoid and pubioischiadic bars evolved. In rays, the pectoral fins have connected to the head and are very flexible. One of the primary characteristics present in most sharks is the heterocercal tail, which aids in locomotion.[3] Body covering[edit] Chondrichthyans have toothlike scales called dermal denticles or placoid scales. Denticles provide two functions, protection and in most cases, streamlining. Mucous glands exist in some species as well. It is assumed that their oral teeth evolved from dermal denticles that migrated into the mouth, but it could be the other way around as the teleost bony fish Denticeps clupeoides has most of its head covered by dermal teeth (as does, probably, Atherion elymus, another bony fish). This is most likely a secondary evolved characteristic, which means there is not necessarily a connection between the teeth and the original dermal scales. The old placoderms did not have teeth at all, but had sharp bony plates in their mouth. Thus, it is unknown whether the dermal or oral teeth evolved first. Nor is it sure how many times it has happened if it turns out to be the case. It has even been suggested that the original bony plates of all the vertebrates are gone and that the present scales are just modified teeth, even if both teeth and the body armor have a common origin a long time ago. However, there is no evidence of this at the moment. Respiratory system[edit] All chondrichthyans breathe through five to seven pairs of gills, depending on the species. In general, pelagic species must keep swimming to keep oxygenated water moving through their gills, whilst demersal species can actively pump water in through their spiracles and out through their gills. However, this is only a general rule and many species differ. A spiracle is a small hole found behind each eye. These can be tiny and circular, such as found on the nurse shark (Ginglymostoma cirratum), to extended and slit-like, such as found on the wobbegongs (Orectolobidae). Many larger, pelagic species, such as the mackerel sharks (Lamnidae) and the thresher sharks (Alopiidae), no longer possess them. Immune system[edit] Like all other jawed vertebrates, members of Chondrichthyes
Chondrichthyes
have an adaptive immune system.[4] Reproduction[edit] Fertilization is internal. Development is usually live birth (ovoviviparous species) but can be through eggs (oviparous). Some rare species are viviparous. There is no parental care after birth; however, some chondrichthyans do guard their eggs. Capture-induced premature birth and abortion (collectively called capture-induced parturition) occurs frequently in sharks/rays when fished.[5] Capture-induced parturition is often mistaken for natural birth by recreational fishers and is rarely considered in commercial fisheries management despite being shown to occur in at least 12% of live bearing sharks and rays (88 species to date).[5] Classification[edit] The class Chondrichthyes
Chondrichthyes
has two subclasses: the subclass Elasmobranchii
Elasmobranchii
(sharks, rays, skates, and sawfish) and the subclass Holocephali
Holocephali
(chimaeras). To see the full list of the species, click here.

Subclasses of cartilaginous fishes

Elasmobranchii

Sharks

and rays, skates, and sawfish

Elasmobranchii
Elasmobranchii
is a subclass that includes the sharks and the rays and skates. Members of the elasmobranchii have no swim bladders, five to seven pairs of gill clefts opening individually to the exterior, rigid dorsal fins, and small placoid scales. The teeth are in several series; the upper jaw is not fused to the cranium, and the lower jaw is articulated with the upper. The eyes have a tapetum lucidum. The inner margin of each pelvic fin in the male fish is grooved to constitute a clasper for the transmission of sperm. These fish are widely distributed in tropical and temperate waters.[6]

Holocephali

Chimaeras

Holocephali
Holocephali
(complete-heads) is a subclass of which the order Chimaeriformes
Chimaeriformes
is the only surviving group. This group includes the rat fishes (e.g., Chimaera), rabbit-fishes (e.g., Hydrolagus) and elephant-fishes (Callorhynchus). Today, they preserve some features of elasmobranch life in Paleaozoic times, though in other respects they are aberrant. They live close to the bottom and feed on molluscs and other invertebrates. The tail is long and thin and they move by sweeping movements of the large pectoral fins. There is an erectile spine in front of the dorsal fin, sometimes poisonous. There is no stomach (that is, the gut is simplified and the 'stomach' is merged with the intestine), and the mouth is a small aperture surrounded by lips, giving the head a parrot-like appearance. The fossil record of the Holocephali
Holocephali
starts in the Devonian
Devonian
period. The record is extensive, but most fossils are teeth, and the body forms of numerous species are not known, or at best poorly understood.

Extant orders of cartilaginous fishes

Group Order Image Common name Authority Families Genera Species Note

Total

Galean sharks Carcharhiniformes

ground sharks Compagno, 1977 8 51 >270 7 10 21

Heterodontiformes

bullhead sharks L. S. Berg, 1940 1 1 9

Lamniformes

mackerel sharks L. S. Berg, 1958 7 +2 extinct 10 16

10

Orectolobiformes

carpet sharks Applegate, 1972 7 13 43

7

Squalomorph sharks Hexanchiformes

frilled and cow sharks de Buen, 1926 2 +3 extinct 4 +11 extinct 6 +33 extinct

Pristiophoriformes

sawsharks L. S. Berg, 1958 1 2 6

Squaliformes

dogfish sharks

1 2 29 1

6

Squatiniformes

angel sharks Buen, 1926 1 1 23 3 4 5

Rays Myliobatiformes

stingrays and relatives Compagno, 1973 10 29 223 1 16 33

Pristiformes

sawfishes

1 2 5-7 5-7

Rajiformes

skates and guitarfishes L. S. Berg, 1940 5 36 >270 4 12 26

Torpediniformes

electric rays de Buen, 1926 2 12 69 2

9

Holocephali Chimaeriformes

chimaera Obruchev, 1953 3 +2 extinct 6 +3 extinct 39 +17 extinct

Taxonomy according to Leonard Compagno, 2005[7] with additions from [8]

†Order Mongolepidiformes Karatajüte-Talimaa & Novitskaya 1990 †Order Omalodontiformes Turner 1997 †Order Coronodontiformes Zangerl 1981 †Order Symmoriiformes Zangerl 1981 Subclass Holocephali

†Superorder Paraselachimorpha

†Order Desmiodontiformes Zangerl 1981 †Order Polysentoriformes Cappetta 1993 †Order Orodontiformes Zangerl 1981 †Order Petalodontiformes
Petalodontiformes
Zangerl 1981 †Order Helodontiformes Patterson 1965 †Order Iniopterygiformes
Iniopterygiformes
Zanger 1973 †Order Debeeriiformes Grogan & Lund 2000 †Order Eugeneodontiformes
Eugeneodontiformes
Zangerl 1981

Superorder Holocephalimorpha

†Order Psammodontiformes* Obruchev 1953 †Order Copodontiformes Obručhev 1953 †Order Squalorajiformes †Order Chondrenchelyiformes Moy-Thomas 1939 †Order Menaspiformes †Order Cochliodontiformes Obručhev 1953 Order Chimaeriformes
Chimaeriformes
Berg 1940 sensu Obručhev 1953 (chimaeras)

Subclass Elasmobranchii

†Plesioselachus †Order Antarctilamniformes Ginter, Liao & Valenzuela-Rios 2008 †Order Elegestolepidiformes Andreev et al. 2016 †Order Lugalepidida Karatajute-Talimaa 1997 †Order Squatinactiformes
Squatinactiformes
Zangerl 1981 †Order Protacrodontiformes
Protacrodontiformes
Zangerl 1981 †Infraclass Cladoselachimorpha

†Order Cladoselachiformes
Cladoselachiformes
Dean 1909

†Infraclass Xenacanthimorpha Berg 1940

†Order Bransonelliformes Hampe & Ivanov 2007 †Order Xenacanthiformes
Xenacanthiformes
Berg 1940

Infraclass Euselachii (sharks and rays)

†Order Altholepidiformes Andreev et al. 2015 †Order Polymerolepidiformes †Order Ptychodontiformes †Order Ctenacanthiformes Zangerl 1981 †Division Hybodonta

†Order Hybodontiformes
Hybodontiformes
Owen 1846

Division Neoselachii Compagno 1977

Subdivision Selachii
Selachii
(modern sharks)

Superorder Galeomorphi
Galeomorphi
Compagno 1977

Order Heterodontiformes
Heterodontiformes
(bullhead sharks) Order Orectolobiformes
Orectolobiformes
(carpet sharks) Order Lamniformes
Lamniformes
(mackerel sharks) Order Carcharhiniformes
Carcharhiniformes
(ground sharks)

Superorder Squalomorphi

Order Chlamydoselachiformes Order Hexanchiformes
Hexanchiformes
(frilled and cow sharks) Order Squaliformes
Squaliformes
(dogfish sharks) †Order Protospinaciformes †Order Synechodontiformes Order Squatiniformes
Squatiniformes
(angel sharks) Order Pristiophoriformes
Pristiophoriformes
(sawsharks)

Subdivision Batoidea
Batoidea
(rays)

Order Torpediniformes
Torpediniformes
(electric rays) Order Pristiformes
Pristiformes
(sawfishes) Order Rajiformes
Rajiformes
(skates and guitarfishes) Order Myliobatiformes
Myliobatiformes
(stingrays and relatives)

* position uncertain

Evolution[edit]

Radiation of cartilaginous fishes, based on Michael Benton, 2005.[9]

See also: Evolution of fish Further information: List of transitional fossils § Chondrichthyes, and List of prehistoric cartilaginous fish Cartilaginous fish
Cartilaginous fish
are considered to have evolved from acanthodians. Originally assumed to be closely related to bony fish or a polyphyletic assemblage leading to both groups, the discovery of Entelognathus
Entelognathus
and several examinations of acanthodian characteristics indicate that bony fish evolved directly from placoderm like ancestors, while acanthodians represent a paraphyletic assemblage leading to Chondrichthyes. Some characteristics previously thought to be exclusive to acanthodians are also present in basal cartilaginous fish.[10] In particular, new phylogenetic studies find cartilaginous fish to be well nested among acanthodians, with Doliodus and Tamiobatis being the closest relatives to Chondrichthyes.[11] Recent studies vindicate this, as Doliodus had a mosaic of chondrichthyian and acanthodiian traits.[12] Unequivocal fossils of cartilaginous fishes first appeared in the fossil record by about 395 million years ago, during the middle Devonian. The radiation of elasmobranches in the chart on the right is divided into the taxa: Cladoselache, Eugeneodontiformes, Symmoriida, Xenacanthiformes, Ctenacanthiformes, Hybodontiformes, Galeomorphi, Squaliformes
Squaliformes
and Batoidea. By the start of the Early Devonian, 419 mya (million years ago), jawed fishes had divided into three distinct groups: the now extinct placoderms (a paraphyletic assemblage of ancient armoured fishes), the bony fishes and the clade including spiny sharks and early cartilaginous fish. The modern bony fishes, class Osteichthyes, appeared in the late Silurian
Silurian
or early Devonian, about 416 million years ago. Cartilaginous fishes first appeared about 395 Ma, having evolved from Doliodus-like spiny shark ancestors. The first abundant genus of shark, Cladoselache, appeared in the oceans during the Devonian
Devonian
Period. A Bayesian analysis of molecular data suggests that the Holocephali and Elasmoblanchii diverged in the Silurian
Silurian
(421 million years ago) and that the sharks and rays/skates split in the Carboniferous (306 million years ago).

Devonian

Devonian
Devonian
(419–359 mya)

Cladoselache Cladoselache
Cladoselache
was the first abundant genus of primitive shark, appearing about 370 Ma.[13] It grew to 6 feet (1.8 m) long, with anatomical features similar to modern mackerel sharks. It had a streamlined body almost entirely devoid of scales, with five to seven gill slits and a short, rounded snout that had a terminal mouth opening at the front of the skull.[13] It had a very weak jaw joint compared with modern-day sharks, but it compensated for that with very strong jaw-closing muscles. Its teeth were multi-cusped and smooth-edged, making them suitable for grasping, but not tearing or chewing. Cladoselache
Cladoselache
therefore probably seized prey by the tail and swallowed it whole.[13] It had powerful keels that extended onto the side of the tail stalk and a semi-lunate tail fin, with the superior lobe about the same size as the inferior. This combination helped with its speed and agility which was useful when trying to outswim its probable predator, the heavily armoured 10 metres (33 ft) long placoderm fish Dunkleosteus.[13]

Carbon- iferous Carboniferous
Carboniferous
(359–299 Ma): Sharks
Sharks
underwent a major evolutionary radiation during the Carboniferous.[14] It is believed that this evolutionary radiation occurred because the decline of the placoderms at the end of the Devonian
Devonian
period caused many environmental niches to become unoccupied and allowed new organisms to evolve and fill these niches.[14]

Orthacanthus
Orthacanthus
senckenbergianus The first 15 million years of the Carboniferous
Carboniferous
has very few terrestrial fossils. This gap in the fossil record, is called Romer's gap after the American palaentologist Alfred Romer. While it has long been debated whether the gap is a result of fossilisation or relates to an actual event, recent work indicates that the gap period saw a drop in atmospheric oxygen levels, indicating some sort of ecological collapse.[15] The gap saw the demise of the Devonian
Devonian
fish-like ichthyostegalian labyrinthodonts, and the rise of the more advanced temnospondyl and reptiliomorphan amphibians that so typify the Carboniferous
Carboniferous
terrestrial vertebrate fauna. The Carboniferous
Carboniferous
seas were inhabited by many fish, mainly Elasmobranchs (sharks and their relatives). These included some, like Psammodus, with crushing pavement-like teeth adapted for grinding the shells of brachiopods, crustaceans, and other marine organisms. Other sharks had piercing teeth, such as the Symmoriida; some, the petalodonts, had peculiar cycloid cutting teeth. Most of the sharks were marine, but the Xenacanthida
Xenacanthida
invaded fresh waters of the coal swamps. Among the bony fish, the Palaeonisciformes
Palaeonisciformes
found in coastal waters also appear to have migrated to rivers. Sarcopterygian fish were also prominent, and one group, the Rhizodonts, reached very large size. Most species of Carboniferous
Carboniferous
marine fish have been described largely from teeth, fin spines and dermal ossicles, with smaller freshwater fish preserved whole. Freshwater fish were abundant, and include the genera Ctenodus, Uronemus, Acanthodes, Cheirodus, and Gyracanthus.

Stethacanthidae

As a result of the evolutionary radiation, carboniferous sharks assumed a wide variety of bizarre shapes; e.g., sharks belonging to the family Stethacanthidae
Stethacanthidae
possessed a flat brush-like dorsal fin with a patch of denticles on its top.[14] Stethacanthus' unusual fin may have been used in mating rituals.[14] Apart from the fins, Stethacanthidae
Stethacanthidae
resembled Falcatus
Falcatus
(below).

Falcatus Falcatus
Falcatus
is a genus of small cladodont-toothed sharks which lived 335–318 Ma. They were about 25–30 cm (9.8–11.8 in) long.[16] They are characterised by the prominent fin spines that curved anteriorly over their heads.

Orodus Orodus
Orodus
is another shark of the Carboniferous, a genus from the family Orodontidae
Orodontidae
that lived into the early Permian
Permian
from 303 to 295 Ma. It grew to 2 m (6.6 ft) in length.

Permian Permian
Permian
(298–252 Ma): The Permian
Permian
ended with the most extensive extinction event recorded in paleontology: the Permian-Triassic extinction event. 90% to 95% of marine species became extinct, as well as 70% of all land organisms. Recovery from the Permian-Triassic extinction event was protracted; land ecosystems took 30M years to recover,[17] and marine ecosystems took even longer.[18]

Triassic Triassic
Triassic
(252–201 Ma): The fish fauna of the Triassic
Triassic
was remarkably uniform, reflecting the fact that very few families survived the Permian
Permian
extinction. In turn, the Triassic
Triassic
ended with the Triassic– Jurassic
Jurassic
extinction event. About 23% of all families, 48% of all genera (20% of marine families and 55% of marine genera) and 70% to 75% of all species became extinct.[19]

Jurassic Jurassic
Jurassic
(201–145 Ma):

Cretaceous Cretaceous
Cretaceous
(145–66 Ma): The end of the Cretaceous
Cretaceous
was marked by the Cretaceous– Paleogene extinction event (K-Pg extinction). There are substantial fossil records of jawed fishes across the K–T boundary, which provides good evidence of extinction patterns of these classes of marine vertebrates. Within cartilaginous fish, approximately 80% of the sharks, rays, and skates families survived the extinction event,[20] and more than 90% of teleost fish (bony fish) families survived.[21]

Squalicorax
Squalicorax
falcatus Squalicorax
Squalicorax
falcatus is a lamnoid shark from the Cretaceous

Ptychodus Ptychodus
Ptychodus
is a genus of extinct hybodontiform shark which lived from the late Cretaceous
Cretaceous
to the Paleogene.[22][23] Ptychodus
Ptychodus
mortoni (pictured) was about 32 feet (9.8 meters) long and was unearthed in Kansas, United States.[24]

Cenozoic Era Cenozoic Era
Cenozoic Era
(65 Ma to present): The current era has seen great diversification of bony fishes.

Megalodon

External video

Megalodon
Megalodon
battle History Channel

The Nightmarish Megalodon
Megalodon
Discovery

Megalodon
Megalodon
is an extinct species of shark that lived about 28 to 1.5 Ma. It looked much like a stocky version of the great white shark, but was much larger with fossil lengths reaching 20.3 metres (67 ft).[25] Found in all oceans[26] it was one of the largest and most powerful predators in vertebrate history,[25] and probably had a profound impact on marine life.[27]

Extinct orders of cartilaginous fishes

Group Order Image Common name Authority Families Genera Species Note

Holocephali †Orodontiformes

†Petalodontiformes

†Helodontiformes

†Iniopterygiformes

†Debeeriiformes

†Symmoiida

[28]

†Eugeneodonti formes

[29]

†Psammodonti formes

Position uncertain

†Copodontiformes

†Squalorajiformes

†Chondrenchelyi formes

†Menaspiformes

†Coliodontiformes

Squalomorph sharks †Protospinaci- formes

Other †Squatinactiformes

†Protacrodonti- formes

†Cladoselachi- formes

†Xenacanthiformes

†Ctenacanthi- formes

†Hybodontiformes

Phylogeny[edit]

Subphylum Vertebrata └─Infraphylum Gnathostomata ├─ Placodermi
Placodermi
— extinct (armored gnathostomes) └ Eugnathostomata
Eugnathostomata
(true jawed vertebrates) ├─ Acanthodii
Acanthodii
(stem cartilaginous fish) └─ Chondrichthyes
Chondrichthyes
(true cartilaginous fish) ├─ Holocephali
Holocephali
(chimaeras + several extinct clades) └ Elasmobranchii
Elasmobranchii
(shark and rays) ├─ Selachii
Selachii
(true sharks) └─ Batoidea
Batoidea
(rays and relatives)

 

Note: lines show evolutionary relationships.

See also[edit]

List of cartilaginous fish Cartilaginous versus bony fishes Largest cartilaginous fishes Threatened rays Threatened sharks

References[edit]

^ Botella, H.A.; Donoghue, P.C.J.; Martínez-Pérez, C. (2009). "Enameloid microstructure in the oldest known chondrichthyan teeth". Acta Zoologica. 90 (Supplement): 103–108. doi:10.1111/j.1463-6395.2008.00337.x. Retrieved 26 November 2013.  ^ "Chondrichthyes". PalaeoDB. Retrieved 26 November 2013.  ^ Wilga, C. D.; Lauder, G. V. (2002). "Function of the heterocercal tail in sharks: quantitative wake dynamics during steady horizontal swimming and vertical maneuvering". Journal of Experimental Biology. 205 (16): 2365–2374.  ^ Flajnik, M. F.; Kasahara, M. (2009). "Origin and evolution of the adaptive immune system: genetic events and selective pressures". Nature Reviews Genetics. 11 (1): 47–59. doi:10.1038/nrg2703. PMC 3805090 . PMID 19997068.  ^ a b Adams, Kye R.; Fetterplace, Lachlan C.; Davis, Andrew R.; Taylor, Matthew D.; Knott, Nathan A. (January 2018). "Sharks, rays and abortion: The prevalence of capture-induced parturition in elasmobranchs". Biological Conservation. 217: 11–27. doi:10.1016/j.biocon.2017.10.010.  ^ Bigelow, Henry B.; Schroeder, William C. (1948). Fishes of the Western North Atlantic. Sears Foundation for Marine Research, Yale University. pp. 64–65. ASIN B000J0D9X6.  ^ Leonard Compagno (2005) Sharks
Sharks
of the World. ISBN 9780691120720. ^ Haaramo, Mikko. Chondrichthyes
Chondrichthyes
– Sharks, Rays and Chimaeras. Retrieved 22 October 2013.  ^ Benton, M. J. (2005). Vertebrate
Vertebrate
Palaeontology (3rd ed.). Blackwell. Fig 7.13 on page 185. ISBN 0-632-05637-1.  ^ Min Zhu; Xiaobo Yu; Per Erik Ahlberg; Brian Choo; Jing Lu; Tuo Qiao; Qingming Qu; Wenjin Zhao; Liantao Jia; Henning Blom; You'an Zhu (2013). "A Silurian
Silurian
placoderm with osteichthyan-like marginal jaw bones". Nature. 502 (7470): 188–193. doi:10.1038/nature12617. PMID 24067611.  ^ Carole Burrow; Jan den Blaauwen; Michael Newman; Robert Davidson (2016). "The diplacanthid fishes (Acanthodii, Diplacanthiformes, Diplacanthidae) from the Middle Devonian
Devonian
of Scotland". Palaeontologia Electronica 19 (1): Article number 19.1.10A. ^ G., Maisey, John; 1956-, Miller, Randall F. (Randall Francis),; Alan., Pradel,; S., Denton, John S.; Allison., Bronson,; Philippe., Janvier, (2017-03-10). "Pectoral morphology in Doliodus : bridging the 'acanthodian'-chondrichthyan divide. (American Museum Novitates, no. 3875)". ^ a b c d The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals 1999, p. 26. ^ a b c d R. Aidan Martin. "A Golden Age of Sharks". Biology of Sharks and Rays. Retrieved 26 November 2013.  ^ Ward, P.; Labandeira, C.; Laurin, M.; Berner, R. A. (2006). "Confirmation of Romer's Gap is a low oxygen interval constraining the timing of initial arthropod and vertebrate terrestrialization". Proceedings of the National Academy of Sciences. 103 (45): 16818–16822. Bibcode:2006PNAS..10316818W. doi:10.1073/pnas.0607824103. PMC 1636538 . PMID 17065318.  ^ "Archived copy". Archived from the original on 21 August 2008. Retrieved 2008-09-04.  Fossil Fish
Fish
of Bear Gulch 2005 by Richard Lund and Eileen Grogan Accessed 2009-01-14 ^ Sahney, S.; Benton, M.J. (2008). "Recovery from the most profound mass extinction of all time". Proceedings of the Royal Society B. 275 (1636): 759–65. doi:10.1098/rspb.2007.1370. PMC 2596898 . PMID 18198148.  ^ Baez. John (2006) Extinction
Extinction
University of California. Retrieved 20 January 2013. ^ "extinction". Math.ucr.edu. Retrieved 26 November 2013.  ^ MacLeod, N; Rawson, PF; Forey, PL; Banner, FT; Boudagher-Fadel, MK; Bown, PR; Burnett, JA; Chambers, P; Culver, S; Evans, SE; Jeffery, C; Kaminski, MA; Lord, AR; Milner, AC; Milner, AR; Morris, N; Owen, E; Rosen, BR; Smith, AB; Taylor, PD; Urquhart, E; Young, JR (1997). "The Cretaceous–Tertiary biotic transition". Journal of the Geological Society. 154 (2): 265–292. doi:10.1144/gsjgs.154.2.0265. Archived from the original on 2007-10-31.  ^ Patterson, C (1993). Osteichthyes: Teleostei. In: The Fossil Record 2 (Benton, MJ, editor). Springer. pp. 621–656. ISBN 0-412-39380-8.  ^ Fossils (Smithsonian Handbooks) by David Ward (Page 200) ^ The paleobioloy Database Ptychodus
Ptychodus
entry accessed on 8/23/09 ^ "Giant predatory shark fossil unearthed in Kansas". BBC - Earth News. 24 February 2010.  ^ a b Wroe, S.; Huber, D. R.; Lowry, M.; McHenry, C.; Moreno, K.; Clausen, P.; Ferrara, T. L.; Cunningham, E.; Dean, M. N.; Summers, A. P. (2008). "Three-dimensional computer analysis of white shark jaw mechanics: how hard can a great white bite?" (PDF). Journal of Zoology. 276 (4): 336–342. doi:10.1111/j.1469-7998.2008.00494.x.  ^ Pimiento, Catalina; Dana J. Ehret; Bruce J. MacFadden; Gordon Hubbell (10 May 2010). Stepanova, Anna, ed. "Ancient Nursery Area for the Extinct Giant Shark
Shark
Megalodon
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from the Miocene of Panama". PLoS ONE. Panama: PLoS.org. 5 (5): e10552. Bibcode:2010PLoSO...510552P. doi:10.1371/journal.pone.0010552. PMC 2866656 . PMID 20479893. Retrieved 12 May 2010.  ^ Lambert, Olivier; Bianucci, Giovanni; Post, Klaas; de Muizon, Christian; Salas-Gismondi, Rodolfo; Urbina, Mario; Reumer, Jelle (1 July 2010). "The giant bite of a new raptorial sperm whale from the Miocene epoch of Peru". Nature. Peru. 466 (7302): 105–108. Bibcode:2010Natur.466..105L. doi:10.1038/nature09067. PMID 20596020.  ^ Coates, M.; Gess, R.; Finarelli, J.; Criswell, K.; Tietjen, K. (2016). "A symmoriiform chondrichthyan braincase and the origin of chimaeroid fishes". Nature. 541: 208–211. doi:10.1038/nature20806.  ^ Tapanila, L; Pruitt, J; Pradel, A; Wilga, C; Ramsay, J; Schlader, R; Didier, D (2013). "Jaws for a spiral-tooth whorl: CT images reveal novel adaptation and phylogeny in fossil Helicoprion" (PDF). Biology Letters. 9: 20130057. doi:10.1098/rsbl.2013.0057. PMC 3639784 . PMID 23445952. [permanent dead link]

Further reading[edit]

Wikispecies
Wikispecies
has information related to Chondrichthyes

The Wikibook Dichotomous Key has a page on the topic of: Chondrichthyes

Taxonomy of Chondrichthyes Images of many sharks, skates and rays on Morphbank

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Extant chordate classes

Kingdom Animalia (unranked) Bilateria Superphylum Deuterostomia

Cephalochordata

Leptocardii (lancelets)

O l f a c t o r e s

Urochordata (tunicates)

Ascidiacea
Ascidiacea
(sea squirts) Appendicularia (larvaceans) Thaliacea
Thaliacea
(pyrosomes, salps, doliolids)

Craniata (Vertebrates + Myxini) (fish + Tetrapods)

Agnatha
Agnatha
(jawless fish)

Cyclostomata

Myxini (hagfish) Hyperoartia
Hyperoartia
(lampreys)

Gnathostomata (jawed vertebrates)

Chondrichthyes
Chondrichthyes
(cartilaginous fish: sharks, rays, chimaeras)

Osteichthyes (bony fish)

Actinopterygii
Actinopterygii
(ray-finned fish)

Sarcopterygii (lobe-finned fish)

Actinistia
Actinistia
(coelacanths)¹

R h i p i d i s t i a

Dipnoi (lungfish)¹

T e t r a p o d a

Amphibia (amphibians)

A m n i o t a

Synapsida

Mammalia (mammals)

Sauropsida (withal Diapsida)

Lepidosauria

Rhynchocephalia
Rhynchocephalia
(tuatara)² Squamata
Squamata
(scaled reptiles)²

Archelosauria

Testudines (turtles)²,³

Archosauria

Crocodilia
Crocodilia
(crocodilians)² Aves (birds)

¹subclasses of Sarcopterygii ²orders of class Reptilia (reptiles) ³traditionally placed in Anapsida italic are paraphyletic groups

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Extant cartilaginous fish orders

Kingdom Animalia Phylum Chordata Subphylum Vertebrata Infraphylum Gnathostomata

Elasmobranchii

Selachii
Selachii
(sharks)

Hexanchiformes
Hexanchiformes
(frilled and cow sharks) Squaliformes
Squaliformes
(dogfish sharks) Pristiophoriformes
Pristiophoriformes
(sawsharks) Squatiniformes
Squatiniformes
(angel sharks) Heterodontiformes
Heterodontiformes
(bullhead sharks) Orectolobiformes
Orectolobiformes
(carpet sharks) Carcharhiniformes
Carcharhiniformes
(ground sharks) Lamniformes
Lamniformes
(mackerel sharks)

Batoidea
Batoidea
(rays)

Torpediniformes
Torpediniformes
(electric rays) Pristiformes
Pristiformes
(sawfishes) Rajiformes
Rajiformes
(skates and guitarfishes) Myliobatiformes
Myliobatiformes
(stingrays and relatives)

Holocephali

Chimaeriformes
Chimaeriformes
(chimaeras)

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Evolution of fish

Forerunners

Cephalochordate

†Pikaia †Cathaymyrus Lancelet

Olfactores

†Haikouella Tunicate †Myllokunmingiidae? †Zhongxiniscus?

Jawless fish

Cyclostomata

Hagfish Hyperoartia

†Haikouichthys Lamprey

†Conodonts

†Protoconodonta? †Paraconodontida †Prioniodontida

†Promissum

†Ostracoderms

†Pteraspidomorphi †Thelodonti †Anaspida †Cephalaspidomorphi

†Galeaspida †Pituriaspida †Osteostraci

Jawed fish

†Placoderms

†Antiarchi †Arthrodira †Brindabellaspida †Petalichthyida †Phyllolepida †Ptyctodontida †Rhenanida † Acanthothoraci
Acanthothoraci
† †Pseudopetalichthyida? †Stensioellida?

†Spiny sharks

†Climatiiformes †Ischnacanthiformes

Cartilaginous

Elasmobranchii Holocephali

Bony

Lobe-finned

†Onychodontida Actinistia

Coelacanth

Dipnomorpha

†Porolepiformes Lungfish

Tetrapodomorpha

Ray-finned

Cladistii Chondrostei Neopterygii

†Semionotiformes Holostei Teleostei

Lists

Lists of prehistoric fish

spiny sharks placoderms cartilaginous bony lobe-finned

List of transitional fossils

Related

Prehistoric life Transitional fossils Vertebrate
Vertebrate
paleontology

† extinct

Taxon identifiers

Wd: Q25371 ADW: Chondrichthyes EoL: 2774522 EPPO: 1CHONC iNaturalist: 196614 ITIS:

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