Promegalops signeuxae

This is another incredibly rare fish from the London Clay with one specimen (the holotype) in public collections (in Paris) and another recently found example by Dan Hogburn. Both of these specimens are incredibly well preserved and show wonderful ornamentation on the top of the skull helping to differentiate from the other species of Promegalops (P.sheppeyensis).

Distinguishing Characteristics:

Large lower jaw with no evidence of teeth present (1)
Large orbit with sclerotic ossicle present (2)
Laterally-narrow, anterior sloping, flat cranium (3)
Distinct and heavy ornamentation to frontal bones on the top of the skull (4)
Distinct gap created between the unusually shaped operculum and supracleithrum (5)

Primary Example: HOLOTYPE MNHN-F-PTE9

Secondary Example: Dan Hogburn recent find

3D Scan: Dan Hogburn Specimen

Side-by-Side Comparison - Promegalops signeuxae

Side-by-Side Comparison - Promegalops signeuxae vs Promegalops sheppeyensis

P.signeuxae showcases clear ornamentation/striations on the frontal bones not present on P.sheppeyensis (1)
P.signeuxae narrows are the front of the skull whereas P.sheppeyensis remains broader (2)
Two clear fenestra (openings) are present on P.signeuxae with only one showing on P.sheppeyensis (3)

References

Casier, E. (1966) Fauna ichthyologique du London Clay. British Museum Natural History London, 1966, 1-496
Monsch, K (2005) Revision of the scombroid fishes from the Cenozoic of England
Raynor, Mitchell, Clouter (2009) London Clay Fossils of Kent and Essex