''Metriorhynchus'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of marine

crocodyliform Crocodyliformes is a clade of crurotarsan archosaurs, the group often traditionally referred to as "crocodilians". They are the first members of Crocodylomorpha to possess many of the features that define later relatives. They are the only pseudo ...

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 German(s) may refer to: * Germany (of or related to) **Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ger ...

palaeontologist Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...

Christian von Meyer in 1832. The name ''Metriorhynchus'' means "Moderate snout", and is derived from the Greek ''Metrio''- ("moderate") and -''rhynchos'' ("snout").

Discovery and species

Fossil specimens referrable to ''Metriorhynchus'' are known from Kimmeridgian (Late Jurassic) deposits of

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

Valid species

Only one valid species is recognized today, the type species ''M. geoffroyii'' (now called ''M. brevirostris''). ''"Metriorhynchus" hastifer'' and ''"M." palpebrosus'' are generically distinct from the ''Metriorhynchus'' type species, with ''hastifer'' being recovered as a geosaurine. 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 ''Suchodus'' is an extinct genus of marine crocodyliform from the Middle to Late Jurassic period of England and France. It measured between in total body length. Taxonomy and phylogeny In the 2000s, phylogenetic analysis has shown that ''Su ...

''. ''Metriorhynchus superciliosus'' has recently been shown to be distinct from the type species, ''M. brevirostris'', and now has its own genus '' Thalattosuchus''. Life reconstruction of Metriorhynchus brevirostris

Life reconstruction of Metriorhynchus brevirostris

The genera ''Purranisaurus'' and ''Suchodus'' have been considered junior synonyms of ''Metriorhynchus''.Steel R. 1973. Crocodylia. ''Handbuch der Paläoherpetologie, Teil 16''. Stuttgart: Gustav Fischer Verlag,116 pp. Recent

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

analyses however, do not support the

monophyly In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic grou ...

of ''Metriorhynchus'', as conceived off in the 1860s-2010.Young MT. 2007. The evolution and interrelationships of Metriorhynchidae (Crocodyliformes, Thalattosuchia). ''Journal of Vertebrate Paleontology'' 27 (3): 170A. Eudes-Deslongchamps (1867–69) recognized four Callovian species of ''Metriorhynchus'': ''M. superciliosus'', ''M. moreli'', ''M. blainvillei'', and ''M. brachyrhynchus''.Eudes-Deslongchamps E. 1867-1869. ''Notes Paléontologiques''. Caen and Paris: 320-392. 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''.Andrews CW. 1913. ''A descriptive catalogue of the marine reptiles of the Oxford Clay, Part Two''. London: British Museum (Natural History), 206 pp. 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''.Adams-Tresman SM. 1987. The Callovian (Middle Jurassic) marine crocodile Metriorhynchus from Central England. ''Palaeontology'' 30 (1): 179-194. Vignaud (1997) however, considered there to be three Callovian species: ''M. superciliosus'', ''M. brachyrhynchus'' and ''M. leedsi,''Vignaud P. (1997). La morphologie dentaire des Thalattosuchia (Crocodylia, Mesosuchia). ''Palaeovertebrata'' 26: 35-59. and a 2022 study describing a new metriorhynchid specimen advocated returning to this taxonomic system, considering '' Gracilineustes'' and ''Thalattosuchus'' junior synonyms of ''Metriorhynchus.''

Unnamed species

Fragmentary remains attributed to ''Metriorhynchus'' are known from South America during the Bajocian and

Bathonian In the geologic timescale the Bathonian is an age and stage of the Middle Jurassic. It lasted from approximately 168.3 Ma to around 166.1 Ma (million years ago). The Bathonian Age succeeds the Bajocian Age and precedes the Callovian Age. Strat ...

(both Middle Jurassic). However, phylogenetic analysis has shown that these species cannot be referred to ''Metriorhynchus''.

References

{{Taxonbar, from=Q132722 Late Jurassic crocodylomorphs of Europe Prehistoric pseudosuchian genera Prehistoric marine crocodylomorphs Late Jurassic genus extinctions Thalattosuchians Fossil taxa described in 1832

Discovery and species

Valid species

Unnamed species

See also

References