Genus: Tyrannoneusteus YOUNG, ANDRADE, BRUSATTE, SAKAMOTO, & LISTON, 2013
Etymology: Greek, tyrant, "an illegitimate ruler" and Greek, -neustes, "swimmer"; tyrant swimmer.

Species: lythrodectikos YOUNG, ANDRADE, BRUSATTE, SAKAMOTO, & LISTON, 2013
Etymology: Greek, lythros, "blood" and Greek, dectikos, "biting"; Blood-biting tyranat swimmer.

Holotype: GLAHM V972

Locality: Fletton, Cambridgeshire County, England, Southern United Kingdom.

Horizon: Peterborough Member, Oxford Clay Formation.


Age: Callovian Stage, Upper Dogger Epoch to Oxfordian Stage, Lower Malm Epoch, Middle Jurassic.

Material: Right mandibular ramus (angular, dentary, splenial, surangular, 8 teeth), fragment of right jugal bar, fragment of right quadratojugal, axis, 4 cervical vertebrae, 9 dorsal vertebrae, 20 caudal vertebrae, numerous dorsal vertebrae transverse process fragments, ribs, right ilium, left ischium, numerous broken and unplaced fragments.

Referred material:

CAMSM J64267: A complete left mandibular ramus.

CGLAHM V1145: Numerous isolated teeth, left humerus, coracoids, femur and ilum.

GLAHM V1399/9: Isolated tooth.

GLAHM V1402/5: Isolated tooth.

GLAHM V1430: Isoalted tooth.

GLAHM V1436: Numerous teeth.

NHMUK PV R3939: Incomplete skull, mandible, with 8 distorted vertebrae (4 cervical and 4 dorsal), and isolated fragments.

PETMG: R176: Almost complete skull.

PETMG:R60: Associated complete, but distorted mandible.


Locality: Benerville-sur-Mer, Calvados Department, Basse-Normandy, France.

Horizon: Marnes de Dives Formation.


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


Joaquim Gameiro Private Collection: Incomplete skull.



Locality: Peterborough, Cambridgeshire County, England, Southern Unitied Kingdom.

Horizon: Corallian Group.


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


NHMUK PV R3939: Tooth.