One of the most important features to help with the identification and classification of extinct fish is the cranial anatomy and particularly the dorsal view of the top of the skull. This unique arrangement of bones within the skull can help significantly in narrowing down the Order and Family that extinct fish may be part of, as well as comparing these to modern extant comparisons.

Within this guide, I’ve taken the most commonly found extinct London Clay fish species and showcased them side by side for comparison purposes. They have been organised into their relevant family groups and included at the start of each group is a modern equivalent from within the relevant family for comparative anatomy purposes. Where known London Clay species are missing, this is because the preservation of the top of the skull was not good enough or because they are a dubious species.

Copyright: The images below have been created and published by Tom Sermon with permission and include specimens from the collections of the Natural History Museum and the OUMNH as well as privately owned specimens. The modern fish skull images used here are credited to Osteobase, World Wide Web electronic publication, osteobase.mnhn.fr.