age
anneal
antiquate
become extinct
become obsolete
calcify
callous
case harden
cornify
date
dated
deaden
fade
firm
fossilate
fossilify
fust
grow old
harden
indurate
lapidify
lithify
lose currency
molder
mummify
obsolesce
ossify
outdate
perish
petrify
qualifier
rust
steel
superannuate
temper
toughen
vitrify
get on
maturate
mature
senesce
fossilized
fossilizes
fossilizing
fossilization
Martian
animals'
antebellum
birds'
cartilaginous
copper-bottomed
decompose
fetal
fibreglass
fleshless
fossil
gummy
half-rotten
hollowed-out
million-year-old
neanderthal
over-populated
prehistoric
self-destructive
single-celled
starfish
three-toed
unhatched
vestigial
whiten