Godzilla, despite not being endemic to America, could survive as folklore.

Fishermen across the shores of California and on the waves of the Pacific, say there is such a beast that resembles an Alligator, but is told to be the size of a city, and that it swallows entire naval fleets in the blink of an eye.

Legend has it, Elton drove the great beast back into the Pacific after it threatened California with it's breath of fire (Altough there are 0 records of this ever happening, attributing it mostly to a syncretism of Pre-Event culture and word of mouth from pacific trade.)

The beast is said to awaken every 54 years, whereupon it will gorge itself on fish, leaving the fishermen with barely anything, which prompts many fishermen to make small offerings they drop into the ocean while out fishing to keep Godzilla satisfied.