Original description species: Duffin & Milàn, 2017
Genus: Oblidens Duffin & Milàn, 2017
Family: Myriacanthidae Woodward, 1889
Suborder: Myriacanthoidei
Order: Chimaeriformes
Subclass: Holocephali

Original description species: Grogan, Lund & Fath, 2014
Genus: Obruchevodus Grogan, Lund & Fath, 2014
Family: Petalodontidae Newberry & Worthen, 1866
Order: Petalodontiformes
Subclass: Euchondrocephali

Original description species: Guinot, Cappetta & Adnet, 2014
Genus: Occitanodus Guinot, Cappetta & Adnet, 2014
Family: Orthacodidae Glikman, 1957
Suborder: Hexanchoidei
Order: Hexanchiformes
Superorder: Squalomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Ctenoptychius crenatus
Original description species: Agassiz, 1844
Genus: Odontacanthus Agassiz, 1845

Synonyms: Hypotodus aculeatus
Original description species: (Cappetta & Case, 1975)
Genus: Odontaspis Agassiz, 1838
Family: Odontaspididae Müller & Henle, 1839
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Case & Borodin, 2000
Genus: Odontaspis Agassiz, 1838
Family: Odontaspididae Müller & Henle, 1839
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Cretolamna complanata, Lamna complanata, Lamna sigmoides, Odontaspis aff. complanata, Odontaspis cf. complanata, Scapanorhynchus complanatus
Original description species: (Egerton, 1844)
Genus: Odontaspis Agassiz, 1838
Family: Odontaspididae Müller & Henle, 1839
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Odontaspis aff. ferox-f, Odontaspis cf. ferox-f, Squalus ferox-f
Original description species: (Risso, 1810)
Genus: Odontaspis Agassiz, 1838
Family: Odontaspididae Müller & Henle, 1839
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Hypotodus grandis
Original description species: (Case, 1978)
Genus: Odontaspis Agassiz, 1838
Family: Odontaspididae Müller & Henle, 1839
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Lamna (Odontaspis) hispida
Original description species: (Rogovich, 1861)
Genus: Odontaspis Agassiz, 1838
Family: Odontaspididae Müller & Henle, 1839
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Carcharias kaikoraensis
Original description species: Davis, 1888
Genus: Odontaspis Agassiz, 1838
Family: Odontaspididae Müller & Henle, 1839
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Carcharias molassicus, Lamna (Odontaspis) molassica, Odontaspis cf. molassica
Original description species: (Probst, 1879)
Genus: Odontaspis Agassiz, 1838
Family: Odontaspididae Müller & Henle, 1839
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Ameghino, 1906
Genus: Odontaspis Agassiz, 1838
Family: Odontaspididae Müller & Henle, 1839
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Ameghino, 1906
Genus: Odontaspis Agassiz, 1838
Family: Odontaspididae Müller & Henle, 1839
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Odontaspis (Odontaspis) sp-f
Genus: Odontaspis Agassiz, 1838
Family: Odontaspididae Müller & Henle, 1839
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Pictet in Pictet & Campiche, 1858
Genus: Odontaspis Agassiz, 1838
Family: Odontaspididae Müller & Henle, 1839
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Carcharias substriata, Carcharias substriatus, Eugomphodus cf. substriata, Odontaspis elegans substriata, Odontaspis macrota striata, Odontaspis substriatus, Odontaspis (Synodontaspis) macrota striata, Odontaspis (Synodontaspis) macrota substriata, Odontaspis (Synodontaspis) substriata, Striatolamia substriata
Original description species: Stromer, 1910
Genus: Odontaspis Agassiz, 1838
Family: Odontaspididae Müller & Henle, 1839
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Odontaspis cf. watinensis
Original description species: Cook, Wilson, Murray, Plint, Newbrey & Everhart, 2013
Genus: Odontaspis Agassiz, 1838
Family: Odontaspididae Müller & Henle, 1839
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Eugomphodus winkleri, Odontaspis aff. winkleri, Odontaspis cf. winkleri, Odontaspis (Synodontaspis) aff. winkleri, Odontaspis (Synodontaspis) winkleri, Synodontaspis winkleri
Original description species: Leriche, 1905
Genus: Odontaspis Agassiz, 1838
Family: Odontaspididae Müller & Henle, 1839
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Salame & Asan, 2019
Genus: Odontorhytis Böhm, 1926
Family: incert. fam.
Order: incert. sedis
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Odontorhytis aff. pappenheimi
Original description species: Böhm, 1926
Genus: Odontorhytis Böhm, 1926
Family: incert. fam.
Order: incert. sedis
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Sambou, Hautier, Sarr, Tabuce, Lihoreau, Thiam, Lebrun, Martin, Cappetta & Adnet, 2020
Genus: Odontorhytis Böhm, 1926
Family: incert. fam.
Order: incert. sedis
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Ohiolepis aff. newberryi
Original description species: (Wells, 1944)
Genus: Ohiolepis Wells, 1944
Family: incert. fam.
Order: incert. sedis
Subclass: Elasmobranchii

Original description species: Wang, 1983
Genus: Ohiolepis Wells, 1944
Family: incert. fam.
Order: incert. sedis
Subclass: Elasmobranchii

Original description species: Welton, 2016
Genus: Oligodalatias Welton, 2016
Family: Dalatiidae Gray, 1851
Order: Squaliformes
Superorder: Squalomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Reinecke, 2015
Genus: Oligoraja Reinecke, 2015
Family: Rajidae De Blainville, 1816
Suborder: Rajoidei
Order: Rajiformes
Superorder: Batomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Phoebodus bryanti
Original description species: (Wells, 1944)
Genus: Omalodus Ginter & Ivanov, 1992
Family: Omalodontidae Ginter, Liao, & Valenzuela-Ríos, 2008
Order: Omalodontiformes
Subclass: Elasmobranchii

Synonyms: Dittodus grabaui
Original description species: (Hussakof & Bryant, 1918)
Genus: Omalodus Ginter & Ivanov, 1992
Family: Omalodontidae Ginter, Liao, & Valenzuela-Ríos, 2008
Order: Omalodontiformes
Subclass: Elasmobranchii

Original description species: Hampe, Aboussalam & Becker, 2004
Genus: Omalodus Ginter & Ivanov, 1992
Family: Omalodontidae Ginter, Liao, & Valenzuela-Ríos, 2008
Order: Omalodontiformes
Subclass: Elasmobranchii

Original description species: Koot, Cuny, Tintori & Twitchett, 2013
Genus: Omanoselache Koot, Cuny, Tintori & Twitchett, 2013
Family: incert. fam.
Order: Hybodontiformes
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Polyacrodus bucheri, Prolatodon bucheri
Original description species: (Cuny, Rieppel & Sander, 2001)
Genus: Omanoselache Koot, Cuny, Tintori & Twitchett, 2013
Family: incert. fam.
Order: Hybodontiformes
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Polyacrodus contrarius, Prolatodon contrarius
Original description species: (Johns, Barnes & Orchard, 1997)
Genus: Omanoselache Koot, Cuny, Tintori & Twitchett, 2013
Family: incert. fam.
Order: Hybodontiformes
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Koot & Cuny, 2015
Genus: Omanoselache Koot, Cuny, Tintori & Twitchett, 2013
Family: incert. fam.
Order: Hybodontiformes
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Koot, Cuny, Tintori & Twitchett, 2013
Genus: Omanoselache Koot, Cuny, Tintori & Twitchett, 2013
Family: incert. fam.
Order: Hybodontiformes
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Onchopristis cruciformis, Onchopristis dunklei dunklei, Sechmetia cruciformis
Original description species: Mcnulty & Slaughter, 1962
Genus: Onchopristis Stromer, 1917
Family: Sclerorhynchidae Cappetta, 1974
Suborder: Sclerorhynchoidei
Order: Rajiformes
Superorder: Batomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Gigantichthys numidus, Onchopristis cf. numidus, Onchopristis foureaui, Platyspondylus foureaui, Sechmetia aegyptiaca, Squatina aegyptiaca
Original description species: (Haug, 1905)
Genus: Onchopristis Stromer, 1917
Family: Sclerorhynchidae Cappetta, 1974
Suborder: Sclerorhynchoidei
Order: Rajiformes
Superorder: Batomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Gigantichthys pharao, Ischyrhiza iwakiensis, Onchosaurus cf. pharao, Onchosaurus iwakiensis, Onchosaurus (Onchosaurus) pharao, Titanichthys pharao
Original description species: (Dames, 1887)
Genus: Onchosaurus Gervais, 1852
Family: Sclerorhynchidae Cappetta, 1974
Suborder: Sclerorhynchoidei
Order: Rajiformes
Superorder: Batomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Onchosaurus cf. radicalis
Original description species: Gervais, 1852
Genus: Onchosaurus Gervais, 1852
Family: Sclerorhynchidae Cappetta, 1974
Suborder: Sclerorhynchoidei
Order: Rajiformes
Superorder: Batomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Roemer, 1885
Genus: Onchus Agassiz, 1837
Family: Onchidae
Order: Ischnacanthiformes

Synonyms: Ctenacanthus heterogyrus
Original description species: Agassiz, 1844
Genus: Onchus Agassiz, 1837
Family: Onchidae
Order: Ischnacanthiformes

Synonyms: Onchus murchisonii
Original description species: Agassiz, 1837
Genus: Onchus Agassiz, 1837
Family: Onchidae
Order: Ischnacanthiformes

Original description species: Kada, 1858
Genus: Onchus Agassiz, 1837
Family: Onchidae
Order: Ischnacanthiformes

Synonyms: Onchus semistriatus
Original description species: Agassiz, 1837
Genus: Onchus Agassiz, 1837
Family: Onchidae
Order: Ischnacanthiformes

Genus: Onychoselache Dick, 1978
Family: incert. fam.
Order: Hybodontiformes
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Dick, 1978
Genus: Onychoselache Dick, 1978
Family: incert. fam.
Order: Hybodontiformes
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Oracanthus confluens, Oracanthus minor
Original description species: Agassiz, 1836
Genus: Oracanthus Agassiz, 1836

Synonyms: Pnigeacanthus deltoides
Original description species: Newberry & Worthen, 1866
Genus: Oracanthus Agassiz, 1836

Original description species: Agassiz, 1837
Genus: Oracanthus Agassiz, 1836

Original description species: Underwood & Cumbaa, 2010
Genus: Orectoloboides Cappetta, 1977
Family: Orectolobidae Gill, 1896
Order: Orectolobiformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Herman & Van Den Eeckhaut, 2010
Genus: Orectoloboides Cappetta, 1977
Family: Orectolobidae Gill, 1896
Order: Orectolobiformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Thies, 1981
Genus: Orectoloboides Cappetta, 1977
Family: Orectolobidae Gill, 1896
Order: Orectolobiformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Werner, 1989
Genus: Orectoloboides Cappetta, 1977
Family: Orectolobidae Gill, 1896
Order: Orectolobiformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Ginglymostoma parvula, Orectoloboides parvulus
Original description species: (Dalinkevicius, 1935)
Genus: Orectoloboides Cappetta, 1977
Family: Orectolobidae Gill, 1896
Order: Orectolobiformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Thies, 1982
Genus: Orectoloboides Cappetta, 1977
Family: Orectolobidae Gill, 1896
Order: Orectolobiformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Adnet, 2006
Genus: Orectoloboides Cappetta, 1977
Family: Orectolobidae Gill, 1896
Order: Orectolobiformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Squatina gippslandicus
Original description species: (Chapman & Cudmore, 1924)
Genus: Orectolobus Bonaparte, 1834
Family: Orectolobidae Gill, 1896
Order: Orectolobiformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Regan, 1906
Genus: Orectolobus Bonaparte, 1834
Family: Orectolobidae Gill, 1896
Order: Orectolobiformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Genus: Orectolobus Bonaparte, 1834
Family: Orectolobidae Gill, 1896
Order: Orectolobiformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Squatiscyllium aff. nigeriensis
Original description species: Cappetta & Case, 2016
Genus: Orectolobus Bonaparte, 1834
Family: Orectolobidae Gill, 1896
Order: Orectolobiformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Lund, 1984
Genus: Orestiacanthus Lund, 1974
Family: Symmoriidae Zangerl, 1990
Order: Symmoriiformes
Superorder: Cladodontomorphi
Subclass: Holocephali

Original description species: Zangerl, 1966
Genus: Ornithoprion Zangerl, 1966
Family: Caseodontidae Zangerl, 1981
Superfamily: Caseodontoidae
Order: Eugeneodontiformes
Subclass: Euchondrocephali

Original description species: Portlock, 1843 (ex Agassiz ms.)
Genus: Orodus Agassiz, 1836
Family: Orodontidae De Koninck, 1878
Order: Orodontiformes
Subclass: Euchondrocephali

Original description species: Agassiz, 1836
Genus: Orodus Agassiz, 1836
Family: Orodontidae De Koninck, 1878
Order: Orodontiformes
Subclass: Euchondrocephali

Synonyms: Orodus cf. decussatus
Original description species: St. John & Worthen, 1875
Genus: Orodus Agassiz, 1836
Family: Orodontidae De Koninck, 1878
Order: Orodontiformes
Subclass: Euchondrocephali

Original description species: Hussakof & Bryant, 1918
Genus: Orodus Agassiz, 1836
Family: Orodontidae De Koninck, 1878
Order: Orodontiformes
Subclass: Euchondrocephali

Original description species: Newberry & Worthen, 1866
Genus: Orodus Agassiz, 1836
Family: Orodontidae De Koninck, 1878
Order: Orodontiformes
Subclass: Euchondrocephali

Synonyms: Orodus angustus
Original description species: Davis, 1883 (ex Agassiz MSS.)
Genus: Orodus Agassiz, 1836
Family: Orodontidae De Koninck, 1878
Order: Orodontiformes
Subclass: Euchondrocephali

Synonyms: Orodus cf. gibbus
Original description species: Portlock (Ex Agassiz), 1843
Genus: Orodus Agassiz, 1836
Family: Orodontidae De Koninck, 1878
Order: Orodontiformes
Subclass: Euchondrocephali

Original description species: Zangerl, 1981
Genus: Orodus Agassiz, 1836
Family: Orodontidae De Koninck, 1878
Order: Orodontiformes
Subclass: Euchondrocephali

Original description species: Chahud, Fairchild & Petri, 2010
Genus: Orodus Agassiz, 1836
Family: Orodontidae De Koninck, 1878
Order: Orodontiformes
Subclass: Euchondrocephali

Synonyms: Orodus cf. mammillaris, Orodus mammilaris
Original description species: Newberry & Worthen, 1866
Genus: Orodus Agassiz, 1836
Family: Orodontidae De Koninck, 1878
Order: Orodontiformes
Subclass: Euchondrocephali

Original description species: Zangerl, 1981
Genus: Orodus Agassiz, 1836
Family: Orodontidae De Koninck, 1878
Order: Orodontiformes
Subclass: Euchondrocephali

Original description species: Würdig-Maciel, 1975
Genus: Orodus Agassiz, 1836
Family: Orodontidae De Koninck, 1878
Order: Orodontiformes
Subclass: Euchondrocephali

Original description species: Newberry & Worthen, 1866
Genus: Orodus Agassiz, 1836
Family: Orodontidae De Koninck, 1878
Order: Orodontiformes
Subclass: Euchondrocephali

Synonyms: Orodus ornatus.
Original description species: Davis, 1883
Genus: Orodus Agassiz, 1836
Family: Orodontidae De Koninck, 1878
Order: Orodontiformes
Subclass: Euchondrocephali

Original description species: Newberry & Worthen, 1866
Genus: Orodus Agassiz, 1836
Family: Orodontidae De Koninck, 1878
Order: Orodontiformes
Subclass: Euchondrocephali

Synonyms: Helodus subteres, Helodus (Psammodus) subteres, Orodus subteres
Original description species: Agassiz, 1836
Genus: Orodus Agassiz, 1836
Family: Orodontidae De Koninck, 1878
Order: Orodontiformes
Subclass: Euchondrocephali

Original description species: Davis, 1883
Genus: Orodus Agassiz, 1836
Family: Orodontidae De Koninck, 1878
Order: Orodontiformes
Subclass: Euchondrocephali

Original description species: Newberry & Worthen, 1866
Genus: Orodus Agassiz, 1836
Family: Orodontidae De Koninck, 1878
Order: Orodontiformes
Subclass: Euchondrocephali

Original description species: St. John & Worthen, 1875
Genus: Orodus Agassiz, 1836
Family: Orodontidae De Koninck, 1878
Order: Orodontiformes
Subclass: Euchondrocephali

Original description species: Adnet, Cappetta, Guinot & Notarbartolo Di Sciara, 2012
Genus: Oromobula Adnet, Cappetta, Guinot & Notarbartolo Di Sciara, 2012
Family: Mobulidae Bonaparte, 1838
Order: Myliobatiformes
Superorder: Batomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Jaekelotodus heersensis, Odontaspis heersensis, Orpodon parvus, Otodus parvus
Original description species: (Herman, 1972)
Genus: Orpodon Cappetta & Nolf, 2005
Family: Odontaspididae Müller & Henle, 1839
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Orthacanthus gracilis Newberry 1875, Pleuracanthus gracilis, Pleuracanthus (Orthacanthus) gracilis
Original description species: Babcock, 2024
Genus: Orthacanthus Agassiz, 1843
Family: Diplodoselachidae Dick, 1981
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii

Synonyms: Orthacanthus (Orthacanthus) bohemicus
Original description species: Fritsch, 1889
Genus: Orthacanthus Agassiz, 1843
Family: Diplodoselachidae Dick, 1981
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii

Synonyms: Chilodus carbonarius, Chilodus tuberosus, Lamna carbonaria
Original description species: (Germar, 1844)
Genus: Orthacanthus Agassiz, 1843
Family: Diplodoselachidae Dick, 1981
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii

Synonyms: Expleuracanthus commailli
Original description species: (Heyler & Poplin, 1982)
Genus: Orthacanthus Agassiz, 1843
Family: Diplodoselachidae Dick, 1981
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii

Synonyms: Ctenacanthus clarki, Ctenacanthus clarkii, Ctenacanthus compressus, Didymodus compressus, Diplodus compressus, Dittodus compressus, Orthacanthus aff. compressus, Orthacanthus arcuatus, Orthacanthus cf. compressus, Pleuracanthus arcuatus, Pleuracanthus cf. arcuatus, Pleuracanthus (Didymodus) compressus, Pleuracanthus (Diplodus) compressus, Xenacanthus cf. compressus, Xenacanthus compressus
Original description species: (Newberry, 1856)
Genus: Orthacanthus Agassiz, 1843
Family: Diplodoselachidae Dick, 1981
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii

Synonyms: Pleuracanthus denticulatus, Pleuracanthus howsei, Xenacanthus howsei
Original description species: (Davis, 1880)
Genus: Orthacanthus Agassiz, 1843
Family: Diplodoselachidae Dick, 1981
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii

Synonyms: Orthacanthus cf. donnelljohnsi
Original description species: Johnson & Thayer, 2010
Genus: Orthacanthus Agassiz, 1843
Family: Diplodoselachidae Dick, 1981
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii

Synonyms: Diplodus equilateralis, Diplodus gibbosus, Dittodus gibbosus, Dittodus parallelus, Lophacanthus taylori, Ochlodus crassus, Orthacanthus cylindricus, Orthacanthus (Orthacanthus) cylindricus, Pleuracanthus cylindricus, Pleuracanthus (Diplodus) equilateralis, Pleuracanthus (Lophacanthus) taylori, Pleuracanthus (Xenacanthus) gibbosus
Original description species: (Binney, 1841)
Genus: Orthacanthus Agassiz, 1843
Family: Diplodoselachidae Dick, 1981
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii

Synonyms: Chilodus gracilis, Orthacanthus cf. gracilis
Original description species: (Giebel, 1848)
Genus: Orthacanthus Agassiz, 1843
Family: Diplodoselachidae Dick, 1981
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii

Original description species: Zidek, 1992
Genus: Orthacanthus Agassiz, 1843
Family: Diplodoselachidae Dick, 1981
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii

Synonyms: Orthacanthus cf. kounoviensis, Orthacanthus (Orthacanthus) kounoviensis
Original description species: Fritsch, 1889
Genus: Orthacanthus Agassiz, 1843
Family: Diplodoselachidae Dick, 1981
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii

Synonyms: Diplodus gracilis, Dittodus gracilis, Xenacanthus gracilis
Original description species: Babcock, 2024
Genus: Orthacanthus Agassiz, 1843
Family: Diplodoselachidae Dick, 1981
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii

Synonyms: Orthacanthus (Orthacanthus) meridionalis
Original description species: Soler-Gijón, 1997
Genus: Orthacanthus Agassiz, 1843
Family: Diplodoselachidae Dick, 1981
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii

Synonyms: Orthacanthus (Orthacanthus) pinguis
Original description species: Fritsch, 1889
Genus: Orthacanthus Agassiz, 1843
Family: Diplodoselachidae Dick, 1981
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii

Synonyms: Diacranodus platypternus, Didymodus platypternus, Orthacanthus aff. platypternus, Xenacanthus platypternus
Original description species: (Cope, 1884)
Genus: Orthacanthus Agassiz, 1843
Family: Diplodoselachidae Dick, 1981
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii

Synonyms: Diacranodus texensis, Didymodus texensis, Orthacanthus aff. texensis, Orthacanthus (Lebachacanthus) texensis, Pleuracanthus texensis, Xenacanthus aff. texensis, Xenacanthus texensis
Original description species: Cope, 1888
Genus: Orthacanthus Agassiz, 1843
Family: Diplodoselachidae Dick, 1981
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii

Synonyms: Orthacanthus buxieri
Original description species: Heyler & Poplin, 1990
Genus: Orthacanthus (Orthacanthus)
Family: Diplodoselachidae Dick, 1981
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii

Original description species: Welton, 2016
Genus: Orthechinorhinus Adnet, 2006
Family: Echinorhinidae Gill, 1862
Order: Echinorhiniformes
Superorder: Squalomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Orthechinorhinus aff. pfeili, Orthechinorhinus cf. pfeili
Original description species: Adnet, 2006
Genus: Orthechinorhinus Adnet, 2006
Family: Echinorhinidae Gill, 1862
Order: Echinorhiniformes
Superorder: Squalomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Coquand, 1860
Genus: Orthodon Coquand, 1860
Family: Scyliorhinidae Gill, 1862
Order: Carcharhiniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Ginter, 2016
Genus: Ossianodus Ginter, 2016
Family: Hybodontidae Owen, 1846
Superfamily: Hybodontoidea
Order: Hybodontiformes
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Marrama, Schultz & Kriwet, 2019
Genus: Ostarriraja Marrama, Schultz & Kriwet, 2019
Family: incert. fam.
Order: Rajiformes
Superorder: Batomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Duffin, 1998
Genus: Ostenoselache Duffin, 1998
Family: Ostenoselachidae Duffin, 1998
Superfamily: Hybodontoidea
Order: Hybodontiformes
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Carcharodon toliapicus ak-suatica
Original description species: (Menner, 1928)
Genus: Otodus Agassiz, 1838
Family: Otodontidae Glickman, 1964
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Carcharocles debrayi, Carcharodon debrayi, Procarcharodon debrayi
Original description species: (Leriche, 1906)
Genus: Otodus Agassiz, 1838
Family: Otodontidae Glickman, 1964
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Davis, 1890
Genus: Otodus Agassiz, 1838
Family: Otodontidae Glickman, 1964
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: (Leriche, 1942)
Genus: Otodus Agassiz, 1838
Family: Otodontidae Glickman, 1964
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Carcharodon minor, Otodus minor minor
Original description species: Giebel, 1848
Genus: Otodus Agassiz, 1838
Family: Otodontidae Glickman, 1964
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Zhelezko in Zhelezko & Kozlov, 1999
Genus: Otodus Agassiz, 1838
Family: Otodontidae Glickman, 1964
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Zhelezko in Zhelezko & Kozlov, 1999
Genus: Otodus Agassiz, 1838
Family: Otodontidae Glickman, 1964
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Zhelezko in Zhelezko & Kozlov, 1999
Genus: Otodus Agassiz, 1838
Family: Otodontidae Glickman, 1964
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Lamna obliqua corbarica
Original description species: (Leriche, 1936)
Genus: Otodus Agassiz, 1838
Family: Otodontidae Glickman, 1964
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Leriche, 1908
Genus: Otodus Agassiz, 1838
Family: Otodontidae Glickman, 1964
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Otodus mugodzharicus
Original description species: Zhelezko in Zhelezko & Kozlov, 1999
Genus: Otodus Agassiz, 1838
Family: Otodontidae Glickman, 1964
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Zhelezko in Zhelezko & Kozlov, 1999
Genus: Otodus Agassiz, 1838
Family: Otodontidae Glickman, 1964
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Zhelezko in Zhelezko & Kozlov, 1999
Genus: Otodus Agassiz, 1838
Family: Otodontidae Glickman, 1964
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Zhelezko in Zhelezko & Kozlov, 1999
Genus: Otodus Agassiz, 1838
Family: Otodontidae Glickman, 1964
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Zhelezko in Zhelezko & Kozlov, 1999
Genus: Otodus Agassiz, 1838
Family: Otodontidae Glickman, 1964
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: (Menner, 1932)
Genus: Otodus Agassiz, 1838
Family: Otodontidae Glickman, 1964
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: (Zhelezko in Zhelezko & Kozlov, 1999)
Genus: Otodus Agassiz, 1838
Family: Otodontidae Glickman, 1964
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Carcharias angustidens, Carcharias turgidus, Carcharocles aff. angustidens, Carcharocles angustidens, Carcharocles angustidens turgidus, Carcharocles cf. angustidens, Carcharocles megalodon angustidens, Carcharocles rectus, Carcharocles turgidus, Carcharodon aff. angustidens, Carcharodon aff. angustidens turgidus, Carcharodon aff. turgidus, Carcharodon angustidens, Carcharodon angustidens angustidens, Carcharodon angustidens turgidus, Carcharodon arndti, Carcharodon augustidens turgidus, Carcharodon cf. angustidens, Carcharodon cf. praemegalodon, Carcharodon cf. turgidus, Carcharodon latidens, Carcharodon longidens, Carcharodon megalodon robustus, Carcharodon praemegalodon, Carcharodon rectus, Carcharodon robustus, Carcharodon simus, Carcharodon turgidus, Otodus angustidens, Otodus angustidens angustidens, Otodus angustidens turgidus, Otodus arndti, Otodus latidens, Otodus rectus, Otodus robustus, Otodus turgidus, Otodus (Carcharocles) aff. angustidens, Otodus (Carcharocles) cf. angustidens, Procarcharodon angustidens, Procarcharodon angustidens angustidens, Procarcharodon cf. angustidens, Procarcharodon latidens, Procarcharodon praemegalodon, Procarcharodon turgidus
Original description species: (Agassiz, 1835)
Genus: Otodus (Carcharocles) Agassiz, 1838
Family: Otodontidae Glickman, 1964
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Carcharias auriculatus, Carcharias canceolatus, Carcharias disauris, Carcharias herodon, Carcharias heterodon, Carcharias leptodon, Carcharias megalotis, Carcharias toliapicus, Carcharocles auriculatus, Carcharocles cf. auriculatus, Carcharocles disauris, Carcharodon auriculatus, Carcharodon auriculatus disauris, Carcharodon auriculatus toliapicus, Carcharodon cf. auriculatus, Carcharodon contortidens, Carcharodon crasidens, Carcharodon disauris, Carcharodon disaurus, Carcharodon heterodon, Carcharodon interamniae, Carcharodon lanciformis, Carcharodon leptodon, Carcharodon megalotis, Carcharodon mortoni, Carcharodon strömeri, Carcharodon sulcatus, Carcharodon toliapicus, Galeocerdo sismonda, Galeocerdo sismondae, Otodus auriculatus, Otodus auriculatus auriculatus, Otodus auriculatus disauris, Otodus contortidens, Otodus crassidens, Otodus disauris, Otodus heterodon, Otodus interamniae, Otodus lanciformis, Otodus leptodon, Otodus megalotis, Otodus mortoni, Otodus orientalis, Otodus toliapicus, Procarcharodon auriculatus, Procarcharodon disauris, Procarcharodon dissauris, Procarcharodon lanciformis, Squalus auriculatus
Original description species: (Blainville, 1818)
Genus: Otodus (Carcharocles) Agassiz, 1838
Family: Otodontidae Glickman, 1964
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Carcharocles aff. sokolovi, Carcharocles auriculatus sokolowi, Carcharocles cf. sokolowi, Carcharocles gr. sokolovi, Carcharocles sokolovi, Carcharocles sokolowi, Carcharodon angustidens sokolowi, Carcharodon sokolovi, Carcharodon sokolowi, Otodus cf. sokolovi, Otodus cf. sokolowi, Otodus sokolovi, Otodus sokolovi sokolovi, Otodus (Carcharocles) cf. sokolovi, Otodus (Carcharocles) cf. sokolowi, Procarcharodon angustidens cf. sokolowi, Procarcharodon cf. sokolowi, Procarcharodon sokolovi, Procarcharodon sokolowi
Original description species: (Jaekel, 1895)
Genus: Otodus (Carcharocles) Agassiz, 1838
Family: Otodontidae Glickman, 1964
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Carcharodon stromeri, Otodus stromeri
Original description species: (Darteville & Casier, 1943)
Genus: Otodus (Carcharocles) Agassiz, 1838
Family: Otodontidae Glickman, 1964
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Carcharias subauriculatus, Carcharocles aff. chubutensis, Carcharocles aff. subauriculatus, Carcharocles cf. chubutensis, Carcharocles chubutensis, Carcharocles megalodon chubutensis, Carcharodon chubutensis, Carcharodon megalodon chubutensis, Carcharodon megalodon subauriculatus, Carcharodon subauricularis, Carcharodon subauriculatus, Corax rothi, Megaselachus chubutensis, Megaselachus rothi, Megaselachus subauriculatus, Otodus chubutensis, Otodus (Megaselachus) cf. chubutensis, Procarcharodon chubutensis, Procarcharodon megalodon chubutensis
Original description species: (Ameghino, 1901)
Genus: Otodus (Megaselachus) Agassiz, 1838
Family: Otodontidae Glickman, 1964
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Carcharias giganteus, Carcharias grosseserratus, Carcharias incidens, Carcharias macrodon, Carcharias megalodon, Carcharias mexicanus, Carcharias polygurus, Carcharias polygyrus, Carcharias productus, Carcharias rectidens, Carcharias semiserratus, Carcharias versus, Carcharias (Prionodon) incidens, Carcharocles aff. megalodon, Carcharocles megalodon, Carcharocles megalodon megalodon, Carcharocles productus, Carcharodon akitaensis, Carcharodon arcuatus, Carcharodon branneri, Carcharodon brevis, Carcharodon cf. megalodon, Carcharodon costae, Carcharodon crassidens, Carcharodon crassirhadix, Carcharodon crassus, Carcharodon crassus NEUGEBOREN, 1850, Carcharodon gibbesi, Carcharodon gigas, Carcharodon helveticus, Carcharodon humilis, Carcharodon intermedius, Carcharodon latissimus, Carcharodon leviathan, Carcharodon megalodon, Carcharodon megalodon indica, Carcharodon megalodon megalodon, Carcharodon megalodon polygyra, Carcharodon megalodon productus, Carcharodon megalodon siculus, Carcharodon megalodon yamanarii, Carcharodon morricei, Carcharodon polygurus, Carcharodon polygyrus, Carcharodon productus, Carcharodon quenstedti, Carcharodon rectidens, Carcharodon rectideus, Carcharodon semiserratus, Carcharodon tumidissimus, Carcharodon turicensis, Cosmopolitodus trigonodon intermedius, Megaselachus megalodon, Megaselachus productus, Otodus megalodon, Otodus polygurus, Otodus (Carcharocles) megalodon, Procarcharodon aff. megalodon, Procarcharodon megalodon, Procarcharodon megalodon megalodon, Selache manzonii, Xenodolamia parvus, Xenodolamia pravus
Original description species: (Agassiz, 1835)
Genus: Otodus (Megaselachus) Agassiz, 1838
Family: Otodontidae Glickman, 1964
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Carcharias lanceolatus, Carcharodon cf. lanceolatus, Carcharodon lanceolatus, Carcharodon obliquus, Cretolamna mediavia, Lamna lanceolata MORTON, 1835, Lamna mediavia, Lamna obliqua, Lamna obliquus, Odontaspis obliqua, Odontaspis taurus obliqua, Otodus cf. obliquus, Otodus giganteus, Otodus lanceolatus, Otodus minor mediavus, Otodus obliquus, Otodus obliquus obliquus, Otodus plicatilis
Original description species: Agassiz, 1838
Genus: Otodus (Otodus) Agassiz, 1838
Family: Otodontidae Glickman, 1964
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Popov, Delsate & Felten, 2019
Genus: Ottangodus Popov, Delsate & Felten, 2019
Family: Rajidae De Blainville, 1816
Suborder: Rajoidei
Order: Rajiformes
Superorder: Batomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Ouledia aff. lacuna
Original description species: Adnet et al., 2020
Genus: Ouledia Cappetta, 1986
Family: Gymnuridae Fowler, 1934
Order: Myliobatiformes
Superorder: Batomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Cappetta, 1986
Genus: Ouledia Cappetta, 1986
Family: Gymnuridae Fowler, 1934
Order: Myliobatiformes
Superorder: Batomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Centrina salvianii-f, Oxynotus aff. centrina-f, Oxynotus cf. centrina-f
Original description species: (Linnaeus, 1758)
Genus: Oxynotus Rafinesque, 1810
Family: Oxynotidae Gill, 1872
Order: Squaliformes
Superorder: Squalomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Welton, 1981
Genus: Oxynotus Rafinesque, 1810
Family: Oxynotidae Gill, 1872
Order: Squaliformes
Superorder: Squalomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Genus: Oxynotus Rafinesque, 1810
Family: Oxynotidae Gill, 1872
Order: Squaliformes
Superorder: Squalomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Ameghino, 1901
Genus: Oxyprinichthys Ameghino, 1901
Family: Lamnidae Bonaparte, 1835
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: Pradel, Maisey, Tafforeau, Mapes & Mallatt, 2014
Genus: Ozarcus Pradel, Maisey, Tafforeau, Mapes & Mallatt, 2014
Family: Falcatidae Zangerl, 1990
Order: Symmoriiformes
Superorder: Cladodontomorphi
Subclass: Holocephali