Although the skeleton is primitive compared to other Mosasauridae in many respects, halisaurines had the distinctive hypocercal tail of other mosasaurids[2] suggesting good swimming ability, and they persisted alongside other mosasaurs until the end of the Cretaceous.

[4] Despite their shortcomings, the Halisaurinae had diversified and reached a global distribution by the end of the Maastrichtian whilst other subfamilies, particularly the Plioplatecarpinae and Tylosaurinae, appear to have been in decline.

Designation of this subfamily followed many decades of confusion surrounding the type genus, Halisaurus, which had long been seen as (and remains) an important taxon in studies of mosasaur phylogeny.

Several discoveries throughout the 1980s and 1990s helped shed light on Halisaurus, with more complete specimens of the type species H. platyspondylus being discovered and Phosphorosaurus ortliebi being momentarily reassigned to the genus by Lingham-Soliar (1996).

[7] Daniel Madzia and Andrea Cau in 2017 defined Halisaurinae as "the most inclusive clade containing Halisaurus platyspondylus, but not Mosasaurus hoffmannii, Tylosaurus proriger, Tethysaurus nopcsai, or Yaguarasaurus colombianus".

The recentmost major phylogenetic analysis of mosasaurs, conducted by Tiago R. Simões and colleagues in May 2017, recovered Halisaurus and the rest of the Halisaurinae as a sister group to the Mosasaurinae instead of the whole Mosasauridae.

The basal mosasaurid Halisaurus sternbergii from the Late Cretaceous of Kansas (North America): a review of the Uppsala type specimen.