i Register
In some senses, fossilized is marked as informal, idiomatic. Watch for register when choosing this word.
ADJ.
based, old
VERB + FOSSILIZED
hands, isn't, pointing, study, yield
FOSSILIZED + NOUN
castillian, footprints, resin, shell, skeleton, stingray
PREP.
on, on, with
ADV.
originally, possibly