On a quick browse I collected these three quotes:
“There have only been two genera of coleoid cephalopods recovered from Oligocene aged sediments of North America;
Oligorostra alabami Ciampaglio & Weaver, 2008 and
Oligosella longi Ciampaglio & Weaver, 2008.” , from Weaver et al. (2010). These are thought to be spirulids and not belosaepiids.
“The oldest Sepiinae (
Sepia and
Archeosepia) occur in the Upper Eocene and Oligocene marls of the Budapest region (Sz6r6nyi, 1933; Wagner, 1938).” , from Hewitt & Pedley (1978).
“Everyone recognises that the older Cenozoic genus
Belosaepia Voltz, 1830 is connected to
Sepia Linnd, 1758 via
Hungarosepia Doyle et al., 1994 ... from the Lutetian-Priabonian of Hungary” , from Hewitt & Jagt (1999).
So a sketched outline might be something like the following?: Late Eocene extinction of
Belosaepia and
Anomalosaepia in American seas; appearance of
Sepia in the seas of Bohemian Europe via
Hungarosepia and the
opening North Atlantic proving an obstacle to migration of
Sepia westwards.