Xenacanthus aff. texensis (1)
(COPE, 1888)
Valid name: Orthacanthus texensis
Valid name: Orthacanthus texensis
Original description species: (COPE, 1888)
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus albuquerquei (3)
(SILVA SANTOS, 1946)
Valid name: Taquaralodus albuquerquei
Valid name: Taquaralodus albuquerquei
Original description species: (SILVA SANTOS, 1946)
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus carinatus (1)
(FRITSCH, 1890)
Valid name: Triodus carinatus
Valid name: Triodus carinatus
Original description species: (FRITSCH, 1890)
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus cf. compressus (1)
(NEWBERRY, 1856)
Valid name: Orthacanthus compressus
Valid name: Orthacanthus compressus
Original description species: (NEWBERRY, 1856)
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus cf. ossiani (1)
JOHNSON, 1999
Valid name: Xenacanthus ossiani
Valid name: Xenacanthus ossiani
Original description species: JOHNSON, 1999
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus compressus (2)
(NEWBERRY, 1856)
Valid name: Orthacanthus compressus
Valid name: Orthacanthus compressus
Original description species: (NEWBERRY, 1856)
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus decheni (29)
(GOLDFUSS, 1847)
Synonyms: Orthacanthus dechenii, Pleuracanthus decheni
Original description species: (GOLDFUSS, 1847)
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus elegans (4)
(TRAQUAIR, 1881)
Synonyms: Pleuracanthus elegans
Original description species: (TRAQUAIR, 1881)
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus gaudryi (2)
(BRONGNIART & SAUVAGE, 1888)
Synonyms: Pleuracanthus gaudryi
Original description species: (BRONGNIART & SAUVAGE, 1888)
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus gracilis (3)
NEWBERRY
Original description species: NEWBERRY
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus humbergensis (5)
HAMPE, 1994
Original description species: HAMPE, 1994
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus laevissimus (9)
(AGASSIZ, 1837)
Synonyms: Pleuracanthus laevissimus
Original description species: (AGASSIZ, 1837)
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus latus (5)
(NEWBERRY & WORTHEN, 1866)
Synonyms: Diplodus latus, Orthacanthus cf. latus
Original description species: (NEWBERRY & WORTHEN, 1866)
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus levidens (1)
FRITSCH, 1875
Original description species: FRITSCH, 1875
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus luedersensis (7)
BERMAN, 1970
Valid name: Barbclabornia luedersensis
Valid name: Barbclabornia luedersensis
Original description species: BERMAN, 1970
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus meisenheimensis (10)
HAMPE, 1994
Original description species: HAMPE, 1994
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus moorei (13)

Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus nebraskensis (5)
JOHNSON, 1984
Valid name: Bransonella nebraskensis
Valid name: Bransonella nebraskensis
Original description species: JOHNSON, 1984
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus oelbergensis (2)
(FRITSCH, 1890)
Original description species: (FRITSCH, 1890)
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus ossiani (2)
JOHNSON, 1999
Synonyms: Xenacanthus cf. ossiani
Original description species: JOHNSON, 1999
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus ovalis (8)
(FRITSCH, 1890)
Synonyms: Pleuracanthus ovalis
Original description species: (FRITSCH, 1890)
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus paralellus (1)
(FRITSCH, 1890)
Valid name: Xenacanthus parallelus
Valid name: Xenacanthus parallelus
Original description species: (FRITSCH, 1890)
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus parallelus (12)
(FRITSCH, 1890)
Synonyms: Pleuracanthus parallelus, Xenacanthus paralellus
Original description species: (FRITSCH, 1890)
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus platypternus (1)
COPE, 1884
Valid name: Orthacanthus platypternus
Valid name: Orthacanthus platypternus
Original description species: COPE, 1884
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus plicatus (2)
FRITSCH, 1879
Valid name: Plicatodus plicatus
Valid name: Plicatodus plicatus
Original description species: FRITSCH, 1879
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus ragonhai (1)
PAULIV, DIAS, SEDOR & RIBEIRO, 2014
Original description species: PAULIV, DIAS, SEDOR & RIBEIRO, 2014
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus remigiusbergensis (6)
HAMPE, 1994
Original description species: HAMPE, 1994
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus santaritensis (1)
RAGONHA, 1984
Original description species: RAGONHA, 1984
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus sessilis (1)

Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus slaughteri (2)
JOHNSON, 1999
Original description species: JOHNSON, 1999
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus sp. (40)

Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus tenuis (3)
(WOODWARD, 1889)
Synonyms: Diplodus tenuis
Original description species: (WOODWARD, 1889)
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus texensis (2)
(COPE, 1888)
Valid name: Orthacanthus texensis
Valid name: Orthacanthus texensis
Original description species: (COPE, 1888)
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus tocantinsensis (1)
SANTOS & SALGADO, 1970
Original description species: SANTOS & SALGADO, 1970
Genus: Xenacanthus BEYRICH, 1848
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenacanthus (Diplodus) plicatus (1)
FRITSCH, 1879
Valid name: Plicatodus plicatus
Valid name: Plicatodus plicatus
Original description species: FRITSCH, 1879
Genus: Xenacanthus (Diplodus)
Family: Xenacanthidae FRITSCH, 1889
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenodolamia aff. simplex (1)
(LEIDY, 1877)
Valid name: Megaselachus simplex
Valid name: Megaselachus simplex
Original description species: (LEIDY, 1877)
Genus: Xenodolamia LEIDY, 1877
Family: incert. fam.
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii
Xenodolamia barbadica (2)
CASIER, 1958
Valid name: Xiphodolamia barbadica
Valid name: Xiphodolamia barbadica
Original description species: CASIER, 1958
Genus: Xenodolamia LEIDY, 1877
Family: incert. fam.
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii
Xenodolamia eocaena (10)
(WOODWARD, 1889)
Valid name: Xiphodolamia eocaena
Valid name: Xiphodolamia eocaena
Original description species: (WOODWARD, 1889)
Genus: Xenodolamia LEIDY, 1877
Family: incert. fam.
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii
Xenodolamia parvus (1)
LEIDY, 1877
Original description species: LEIDY, 1877
Genus: Xenodolamia LEIDY, 1877
Family: incert. fam.
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii
Xenodolamia pravus (2)
LEIDY, 1877
Valid name: Megaselachus pravus
Valid name: Megaselachus pravus
Original description species: LEIDY, 1877
Genus: Xenodolamia LEIDY, 1877
Family: incert. fam.
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii
Xenodolamia simplex (2)
LEIDY, 1877
Valid name: Megaselachus simplex
Valid name: Megaselachus simplex
Original description species: LEIDY, 1877
Genus: Xenodolamia LEIDY, 1877
Family: incert. fam.
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii
Xenodolamia sp. (3)

Genus: Xenodolamia LEIDY, 1877
Family: incert. fam.
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii
Xenodus hertzeri (1)
(NEWBERRY, 1889)
Original description species: (NEWBERRY, 1889)
Genus: Xenodus MILLER, 1892
Family: Cochliodontidae OWEN, 1867
Order: Cochliodontiformes
Superorder: Holocephalimorpha
Subclass: Holocephali
Xenodus herzeri (1)
(NEWBERRY, 1889)
Original description species: (NEWBERRY, 1889)
Genus: Xenodus MILLER, 1892
Family: Cochliodontidae OWEN, 1867
Order: Cochliodontiformes
Superorder: Holocephalimorpha
Subclass: Holocephali
Xenosynechodus egloni (5)
GLIKMAN, 1980
Original description species: GLIKMAN, 1980
Genus: Xenosynechodus GLIKMAN, 1980
Family: Xenosynechodontidae GLICKMAN, 1980
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xenosynechodus sp. (1)

Genus: Xenosynechodus GLIKMAN, 1980
Family: Xenosynechodontidae GLICKMAN, 1980
Order: Xenacanthiformes
Superorder: Xenacanthimorpha
Subclass: Elasmobranchii
Xinjiangichthys pluridentatus (2)
WANG, ZHANG, WANG & ZHU, 1998
Original description species: WANG, ZHANG, WANG & ZHU, 1998
Genus: Xinjiangichthys WANG, ZHANG, WANG & ZHU, 1998
Family: Shiqianolepidae SANSOM, ALDRIDGE & SMITH, 2000
Suborder: KARATAJUTE-TALIMAA, NOVITSKAYA, ROZMAN & SODOV, 1990
Order: Mongolepidida
Xinjiangichthys tarimensis (1)
WANG, ZHANG, WANG & ZHU, 1998
Original description species: WANG, ZHANG, WANG & ZHU, 1998
Genus: Xinjiangichthys WANG, ZHANG, WANG & ZHU, 1998
Family: Shiqianolepidae SANSOM, ALDRIDGE & SMITH, 2000
Suborder: KARATAJUTE-TALIMAA, NOVITSKAYA, ROZMAN & SODOV, 1990
Order: Mongolepidida
Xiphodolamia ensis (16)
LEIDY, 1877
Synonyms: Xyphodolamia ensis
Original description species: LEIDY, 1877
Genus: Xiphodolamia LEIDY, 1877
Family: Lamnidae MÜLLER & HENLE, 1838
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii
Xiphodolamia eocaena (26)
(WOODWARD, 1889)
Synonyms: Carcharias (Scoliodon) eocaenus, Isurus eocaenus, Oxyrhina eocaena, Oxyrhina zignoi, Rhizoprionodon eocaenus, Xenodolamia eocaena, Xiphodolamia eocenica, Xiphodolamia zignoi
Original description species: (WOODWARD, 1889)
Genus: Xiphodolamia LEIDY, 1877
Family: Lamnidae MÜLLER & HENLE, 1838
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii
Xiphodolamia eocenica (3)
(WOODWARD, 1889)
Valid name: Xiphodolamia eocaena
Valid name: Xiphodolamia eocaena
Original description species: (WOODWARD, 1889)
Genus: Xiphodolamia LEIDY, 1877
Family: Lamnidae MÜLLER & HENLE, 1838
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii
Xiphodolamia morricei (1)
(JORDAN & BEAL, 1913)
Valid name: Hemipristis serra
Valid name: Hemipristis serra
Original description species: (JORDAN & BEAL, 1913)
Genus: Xiphodolamia LEIDY, 1877
Family: Lamnidae MÜLLER & HENLE, 1838
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii
Xiphodolamia serrata (3)
ADNET & HOSSEINZADEH & ANTUNES & BALBINO & KOZLOV & CAPPETTA, 2009
Original description species: ADNET & HOSSEINZADEH & ANTUNES & BALBINO & KOZLOV & CAPPETTA, 2009
Genus: Xiphodolamia LEIDY, 1877
Family: Lamnidae MÜLLER & HENLE, 1838
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii
Xiphodolamia sp. (5)

Genus: Xiphodolamia LEIDY, 1877
Family: Lamnidae MÜLLER & HENLE, 1838
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii
Xiphotrygon acutidens (3)
COPE, 1879
Valid name: Heliobatis radians
Valid name: Heliobatis radians
Original description species: COPE, 1879
Genus: Xiphotrygon COPE, 1879
Family: Dasyatidae JORDAN, 1888
Order: Myliobatiformes
Superorder: Batomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii
Xyphodolamia ensis (1)
LEIDY, 1877
Valid name: Xiphodolamia ensis
Valid name: Xiphodolamia ensis
Original description species: LEIDY, 1877
Genus: Xyphodolamia
Xystracanthus arcuatus (1)
LEIDY, 1859
Original description species: LEIDY, 1859
Genus: Xystracanthus LEIDY, 1859
Subclass: Elasmobranchii
Xystracanthus konincki (1)
LOHEST, 1878
Original description species: LOHEST, 1878
Genus: Xystracanthus LEIDY, 1859
Subclass: Elasmobranchii
Xystrodus alatus (1)
DE KONINCK, 1878
Original description species: DE KONINCK, 1878
Genus: Xystrodus PLIENINGER IN SCHLÖNBACH, 1860
Family: Hybodontidae OWEN, 1846
Superfamily: Hybodontoidea
Order: Hybodontiformes
Cohort: Euselachii
Subclass: Elasmobranchii
Xystrodus egertoni (1)
DAVIS, 1883
Original description species: DAVIS, 1883
Genus: Xystrodus PLIENINGER IN SCHLÖNBACH, 1860
Family: Hybodontidae OWEN, 1846
Superfamily: Hybodontoidea
Order: Hybodontiformes
Cohort: Euselachii
Subclass: Elasmobranchii
Xystrodus finitimus (1)
PLIENINGER, 1860
Original description species: PLIENINGER, 1860
Genus: Xystrodus PLIENINGER IN SCHLÖNBACH, 1860
Family: Hybodontidae OWEN, 1846
Superfamily: Hybodontoidea
Order: Hybodontiformes
Cohort: Euselachii
Subclass: Elasmobranchii
Xystrodus occidentalis (1)
ST. JOHN, 1870
Original description species: ST. JOHN, 1870
Genus: Xystrodus PLIENINGER IN SCHLÖNBACH, 1860
Family: Hybodontidae OWEN, 1846
Superfamily: Hybodontoidea
Order: Hybodontiformes
Cohort: Euselachii
Subclass: Elasmobranchii
Xystrodus striatus (2)
DAVIS, 1883
Valid name: Platyxystrodus striatus
Valid name: Platyxystrodus striatus
Original description species: DAVIS, 1883
Genus: Xystrodus PLIENINGER IN SCHLÖNBACH, 1860
Family: Hybodontidae OWEN, 1846
Superfamily: Hybodontoidea
Order: Hybodontiformes
Cohort: Euselachii
Subclass: Elasmobranchii
Xystrodus verus (1)
DAVIS, 1883
Original description species: DAVIS, 1883
Genus: Xystrodus PLIENINGER IN SCHLÖNBACH, 1860
Family: Hybodontidae OWEN, 1846
Superfamily: Hybodontoidea
Order: Hybodontiformes
Cohort: Euselachii
Subclass: Elasmobranchii
Xystrogaleus cappettai (3)
ADNET, 2006
Original description species: ADNET, 2006
Genus: Xystrogaleus ADNET, 2006
Family: Triakidae GRAY, 1851
Order: Carcharhiniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii