Metriorhynchus Temporal range: Kimmeridgian,
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Partial holotype rostrum (MHNG V-2232) of M. brevirostris as illustrated in 1824 | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Clade: | Archosauria |
Clade: | Pseudosuchia |
Clade: | Crocodylomorpha |
Clade: | Crocodyliformes |
Suborder: | †Thalattosuchia |
Family: | †Metriorhynchidae |
Genus: | †Metriorhynchus von Meyer, 1832[2] |
Species: | †M. brevirostris
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Binomial name | |
†Metriorhynchus brevirostris (Holl, 1828) vide Young et al., 2020[1]
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Synonyms | |
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Metriorhynchus is an extinct genus of marine crocodyliform that lived in the oceans during the Late Jurassic. The type species, M. brevirostris was named in 1829 as a species of Steneosaurus before being named as a separate genus by the German palaeontologist Christian von Meyer in 1832.[2] The name Metriorhynchus means "Moderate snout", and is derived from the Greek Metrio- ("moderate") and -rhynchos ("snout").
Fossil specimens referrable to Metriorhynchus are known from Kimmeridgian (Late Jurassic) deposits of France.[1]
Only one valid species is recognized today, the type species M. geoffroyii (now called M. brevirostris).[1] "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.[1]
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][1]
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]
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][1]