Hello Henrik and paleonetters,
I am not sure if it was ever published, but I'm fairly sure that there was
a masters thesis of fossil fish otoliths written at the University of
Delaware around 1979 or 1980 by Sandra Schaeffer. You can try contacting
the Geology Dept. at the University to get the details.
Dept. of Geology
University of Delaware
Newark, DE 19716
USA
Elana Benamy
Collection Manager, Invert. Paleo.
Academy of Natural Sciences of Philadelphia
benamy@say.acnatsci.org