Xiphactinus

Xiphactinus
Temporal range: AlbianMaastrichtian
Mounted skeleton of X. audax at the American Museum of Natural History
Scientific classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Ichthyodectiformes
Family: Ichthyodectidae
Subfamily: Ichthyodectinae
Genus: Xiphactinus
Leidy, 1870
Type species
Xiphactinus audax
Leidy, 1870
Species
  • X. audax Leidy, 1870
  • X. vetus Leidy, 1856
Synonyms
List of synonyms
  • Synonyms of X. audax
      • Saurocephalus audax Cope, 1870
      • Saurocephalus thaumas Cope, 1870
      • Portheus molossus Cope, 1871
      • Portheus thaumas Cope, 1871
      • Portheus lestrio Cope, 1873
      • Portheus mudgei Cope, 1874
      • Portheus lowii Stewart, 1898
      • Xiphactinus molossus Stewart, 1898
      • Xiphactinus thaumas Stewart, 1898
      • Xiphactinus brachygnathus Stewart, 1899
      • Xiphactinus lowii Stewart, 1900
      • Xiphactinus gaultinus Newton, 1877
      • Xiphactinus mantelli Newton, 1877
      • Megalodon sauroides Agassiz, 1835
      • Megalodon? lewesiensis Mantell, 1836
      • Hypsodon lewesiensis Agassiz, 1843
      • Portheus mantelli Newton, 1877
      • Portheus daviesi Newton, 1877
    Synonyms of X. vetus
      • Polygonodon vetus Leidy, 1856
      • Polygonodon rectus Emmons, 1858
      • Mossasaurus rectus Emmons, 1858
      • Portheus angulatus Cope, 1872
      • Xiphactinus angulatus Schwimmer et al., 1992

Xiphactinus (from Latin and Greek for "sword-ray") is an extinct genus of large predatory marine ray-finned fish that lived during the late Albian to the late Maastrichtian. The genus grew up to 5–6 metres (16–20 ft) in length, and superficially resembled a gargantuan, fanged tarpon. It is a member of the extinct order Ichthyodectiformes, which represent close relatives of modern teleosts.

The species Portheus molossus described by Cope is a junior synonym of X. audax. Skeletal remains of Xiphactinus have come from the Carlile Shale and Greenhorn Limestone of Kansas (where the first Xiphactinus fossil was discovered during the 1850s in the Niobrara Chalk), and Cretaceous formations all over the East Coast (most notably Georgia, Alabama, North Carolina, and New Jersey) in the United States, as well as Europe, Australia, the Kanguk and Ashville Formations of Canada, La Luna Formation of Venezuela and the Salamanca Formation in Argentina.