prehistoric (adj.)

• aboriginal
• ancestral
• ancient
• antediluvian
• antiquated
• atavistic
• autochthonous
• earliest
• early
• erstwhile
• fore
• former
• fossil
• immemorial
• late
• old
• old-fashioned
• olden
• onetime
• passe
• past
• patriarchal
• previous
• primal
• prime
• primeval
• primitive
• primordial
• prior
• pristine
• quondam
• recent
• sometime
• then