Genus: Gracilienustes YOUNG, BRUSATTE, RUTA & DE ANDRADE, 2010
Etymology: 'Gracile swimmer'. In reference to the slender nature of both thier longirostrine crania and postcrania in comparison with other Callovian forms.

Species: leedsi (ANDREWS, 1913) YOUNG, BRUSATTE, RUTA & DE ANDRADE, 2010
= Metriorhynchus leedsi ANDREWS, 1913
Etymology: In honor of Alfread Leeds, a quarry owner and amateur palaeontologist, from whose quarry a diverse assemblage of Oxford Clay marine reptiles were discovered.

Holotype: BMNH R3540

Locality: Close to Peterborough, Cambridgeshire County, England, Southern United Kingdom.

Horizon: Middle Oxford Clay Formation..

Biostratigraphy: calloviense-lamberti ammonite zones (old Jason and coronatum zones).

Age: Middle-Late Callovian Stage, Upper Dogger Epoch, Middle Jurassic.

Material: Skull.

Referred material:

BMNH R3899, PETMG (CMP) R24: Skulls.

YOUNG, BRUSATTE, RUTA & DE ANDRADE, 2010

CAMSM J64297: Skull with mandible.

GLAHM V973: Skull with mandible.

GLAHM V974: Incomplete skull.

GLAHM V975: Incomplete skull.

NHM R.5793: Incomplete skull.

PETMG R72: Incomplete skull.

= Metriorhynchus laeve ANDREWS, 1913
= Metriorhynchus laevis KUHN, 1936 (sic)
= Metriorhynchus loeve WENZ, 1968 (sic)

= Metriorhynchus laeve ANDREWS, 1913
Etymology:

Holotype: BMNH R3015

Locality: Close to Peterborough, Cambridgeshire County, England, Southern United Kingdom.

Horizon: Oxford Clay.

Biostratigraphy: Jason and coronatum zones.

Age: Callovian Stage, Upper Dogger Epoch, Middle Jurassic.

Material: Skull, mandible, atlas, axis, 5 cervical, 16 dorsal vertebrae, cervical and dorsal ribs, coracoid, scapula, humerus, and right femur.

Referred material:

BMNH R2031: Imperfect skull of a juvenile.

BMNH R2042: Imperfect skull and mandible, teeth, imperfect atlas and axis, 3 cervical and 20 other much crushed vertebrae and numerous fragments of ribs.

BMNH R3014: Skull, mandible, atlas, axis, 5 cervical, 16 dorsals, 2 sacral, 35 caudal vertebrae, numerous cervical and dorsal ribs, right coracoid and scapula, humerus, right femur, tibia, fibula, and lost all the bones of the tarsus and pes, some chevrons.

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Species: acutus (LENNIER, 1887) YOUNG, BRUSATTE, RUTA & DE ANDRADE, 2010
= Metriorhynchus acutus LENNIER, 1887
Etymology: 'Sharp-pointed gracile swimmer', because the holotype skull had a very thing snout that gave it a 'sharper' appearance.

Holotype: Destroyed/lost during World War II.

Locality: Cap de la Heve, Normandy, France.

Horizon:

Biostratigraphy: cymodoce ammointe zone.

Age: Lower Kimmeridgian Stage, Middle Malm Epoch, Late Jurassic.

Material: Skull and lower jaw.
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