This link has a fossil photo of the silverfish Ramsdelepidion schusteri. It
was found in the Mazon Creek deposits in Illinois. The fossil dates to the
Pennsylvanian division (359 - 299 million years ago) of the Carboniferous.
http://www.thenaturalcanvas.com/Mazoncreek/pages/5994.html

This link has a photo of a silverfish fossi. The genus, species and family
of it have not yet been determined. This insect fossil was found in the Crato
Member of the Santana Formation. The strata in which it was discovered dates to
a lower Cretaceous span of 114-112 million years ago (Late Aptian).

http://www.fossilmuseum.net/Fossil_Sites/Santana-Formation/thysanura/thysanurab.\
htm

Neal Robbins