After Bell, 1997, Lindgren & Siverson, 2005, and Bardet, Pereda Suberbiola, Iarochène, Bouya & Amaghzaz, 2005

<==o †Mosasauridae Gervais, 1853 (Large Sea Lizards; “suurmeriliskot”)
   |?- †Goronyosaurus nigeriensis Azzaroli, de Guili, Ficcarelli & Torre, 1972
   |?- †Haasiasaurus gittelmani Polcyn, Tchernov & Jacobs, 2003 [Haasia Polcyn, Tchernov & Jacobs, 1999; non Haasia Bollman, 1893 (Myriapoda) nor Haasia Yuan, 1988 (Trilobita)]
   |--o †Halisaurinae Bardet & Pereda Suberbiola in Bardet, Pereda Suberbiola, Iarochène, Bouya & Amaghzaz, 2005
   |  |--o †Eonatator Bardet, Pereda Suberbiola, Iarochène, Bouya & Amaghzaz, 2005
   |  |  |-- †E. sp. cf. H. sternbergi (Bell, 1997) [Halisaurus sp. cf. H. sternbergi (Bell, 1997)]
   |  |  `-- †E. sternbergi (Wiman, 1920) Bardet, Pereda Suberbiola, Iarochène, Bouya & Amaghzaz, 2005 [Clidastes sternbergi Wiman, 1920; †Halisaurus sternbergi (Wiman) Bell, 1997; †Halisaurus sternbergi (Wiman) Lindgren & Siverson, 2005]
   |  `--o †Halisaurus Marsh, 1869 sensu Bardet, Pereda Suberbiola, Iarochène, Bouya & Amaghzaz, 2005
   |     |?- †Phosphorosaurus ortliebi Dollo, 1889 [taxonomic history]
   |     `--o †Halisaurus Marsh, 1869 [taxonomic history]
   |        |?- †H. onchognathus (Merriam, 1894) [taxonomic history]
   |        |?- †H. walkeri (Lingham-Solier, 1998) [taxonomic history]
   |        |-- †H. arambourgi Bardet, Pereda Suberbiola, Iarochène, Bouya & Amaghzaz, 2005
   |        `-- †H. platyspondylus Marsh, 1869
   `--o †Natantia Owen, 1849-1884
      |-- †Mosasaurinae (Gervais, 1853) Williston, 1897 
      `-- †Russelosaurina Polcyn & Bell, 2005 [Tylosaurinae & Plioplatecarpinae]

Alternative phylogeny after Polcyn & Bell, 2005, and Cuthbertson, Mallon, Campione & Holmes, 2007

<==o †Mosasauridae
   |?- †Goronyosaurus
   |-- †Mosasaurinae
   `--+-- †Haasiasaurus
      `--+--+-- Trieste Aigialosaurid
         |  `--o †Halisaurinae
         |     |-- †Eonatator
         |     `--o †Halisaurus
         |        |?- †Phosphorosaurus
         |        `-- †Halisaurus s.s.
         `--o †Russelosaurina
            |-- †“Russellosaurinae”
            `--+-- †Tylosaurinae
               `-- †Plioplatecarpinae

Reference(s):