When you say became, should i take that to mean evolved into? Because if things are happening on an evolutionary timescale (millions of years for any but the most minor change), then again, all bets are off and most anything is possible.
i was thinking more an adaptation to the underground lifestyle than any form of evolution. evolution takes a long time adaptation does not.
You could always use Miami or Tampa with water elevations another 20 - 50 feet higher to get what you need
its more an intentional play on names though. then again in a few hundred years it could be just someone found the sign and recycled it down the road.