''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 living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

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 pseu ...

that lived in the oceans during the

Late Jurassic The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the name ...

. The type species, ''M. brevirostris'' was named in 1829 as a species of ''

Steneosaurus ''Steneosaurus'' (from el, στενός , 'narrow' and el, σαῦρος , 'lizard') is a dubious genus of teleosaurid crocodyliform from the Middle or Late Jurassic ( Callovian or early Oxfordian) of France. The genus has been used as a w ...

'' 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 **Ge ...

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 foss ...

Christian von Meyer in 1832. The name ''Metriorhynchus'' means "Moderate snout", and is derived from the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

''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 ' ...

''. ''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 ...

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 ...

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 Morphometrics (from Greek μορϕή ''morphe'', "shape, form", and -μετρία ''metria'', "measurement") or morphometry refers to the quantitative analysis of ''form'', a concept that encompasses size and shape. Morphometric analyses are co ...

, 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 ''Gracilineustes'' is an extinct genus of marine crocodyliform that lived in the oceans during the Middle to Late Jurassic. ''Gracilineustes'' was a carnivore that spent much, if not all, its life out at sea. It measured about long and weighed ...

'' and ''Thalattosuchus'' junior synonyms of ''Metriorhynchus.''

Unnamed species

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

Bajocian In the geologic timescale, the Bajocian is an age and stage in the Middle Jurassic. It lasted from approximately 170.3 Ma to around 168.3 Ma (million years ago). The Bajocian Age succeeds the Aalenian Age and precedes the Bathonian Age. Stra ...

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. ...

(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