Xiphiorhynchus priscus

Xiphiorhynchus priscus differs to the modern swordfish as both their upper and lower jaws formed elongated rostrums (compared to just the upper bill in modern swordfish).

There are a number of excellent fossil skulls which have been found over the years but they are nearly always missing the bill as this is very fragile and is often broken off and found separately.

Xiphias gladius Linnaeus, 1758 Observed in Australia by Ken Graham (licensed under http://creativecommons.org/licenses/by-nc/4.0/)

Distinguishing Characteristics:

Large sclerotic ossicle in orbit (1)
Elongated jaws forming a rostrum/bill (2)
Centrally-radiating ornamentation on frontal bones (3)
Tiny teeth creating an abrasive surface on both upper and lower jaws of the rostrum (4)

Primary Example: NHMUK PV P 26990

3D Scan - NHMUK PV P 26990

3D scans undertaken by Tom Sermon with permission. From the collections of the Natural History Museum, London

Additional example: NHMUK PV P 13056

Additional example: Dan Hogburn Specimen

3D Scan - Dan Hogburn specimen

3D scans undertaken by Tom Sermon with permission.

Additional example: Dan Hogburn Specimen - Lower jaw rostrum

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