Valid species

Only one valid species is recognized today, the type species M. geoffroyii (now called M. brevirostris).^[2] "Metriorhynchus" hastifer and "M." palpebrosus are generically distinct from the Metriorhynchus type species, with hastifer being recovered as a geosaurine.^[3][4] Species in this genus were traditionally classed into two skull groups: longirostrine (long, narrow jaws) and brevirostrine (short, broad jaws). However, most of brevirostrine species have been transferred to the genera Purranisaurus and Suchodus.^[5][6] Metriorhynchus superciliosus was also shown to be generically distinct from the type species, M. brevirostris, and now has its own genus Thalattosuchus.^[2]

The genera Purranisaurus and Suchodus have been considered junior synonyms of Metriorhynchus.^[7] Recent phylogenetic analyses however, do not support the monophyly of Metriorhynchus, as believed during the 1860s-2010.^{[8][9][10][2]}

Eudes-Deslongchamps (1867–69) recognized four Callovian species of Metriorhynchus: M. superciliosus, M. moreli, M. blainvillei, and M. brachyrhynchus.^[11] Later, Andrews (1913) considered there to be seven valid species: M. superciliosus, M. moreli, M. brachyrhynchus, M. durobrivensis, M. cultridens, M. leedsi and M. laeve.^[12] However, Adams-Tresman (1987), using linear morphometrics, could only distinguish between the two skull groups, so she found there to be two species from the Oxford Clay, M. superciliosus and M. brachyrhynchus.^[13] Vignaud (1997) however, considered there to be three Callovian species: M. superciliosus, M. brachyrhynchus and M. leedsi,^[14] and a 2022 study describing a new metriorhynchid specimen advocated returning to this taxonomic system, considering Gracilineustes and Thalattosuchus junior synonyms of Metriorhynchus.^[15]

Unnamed species

Fragmentary remains attributed to Metriorhynchus are known from South America during the Bajocian^[16] and Bathonian (both Middle Jurassic).^[17] However, phylogenetic analysis has shown that these species cannot be referred to Metriorhynchus.^[5][18][2]