Choctaw Sea

At its maximum coverage it encompassed an area as far north as the city of Bainbridge in Southwest Georgia and as far to the southeast as Taylor County, Florida, United States.

This period spanned the existence of the Gulf Trough between Georgia and Florida's Orange Island.

Basilosaurus cetoides and Zygorhiza, early toothed whales, as well as Protosiren, an extinct ancestor of the Manatee, inhabit these waters and are the earliest mammal fossils uncovered with specimens from Citrus County in dolomite ~40—37 Ma.

The Chattahoochie Subsea was much smaller in size than the Bainbridge and during the filling of the Chattahoochee, the St. Marks Formation of limestone and sand was established.

The fossil record shows that land animals entered the newly formed peninsula ~24.8 Ma.

It was replenished with the Zanclean flood which raised the world-wide sea level 10 meters or 33 feet.

Table displaying the Choctaw Sea and its relation to geologic time and North American Land Mammal Ages . Dry periods or marine regressive periods are tan in color.
Depiction of Oligocene Orange Island which was the first emerging landmass.
Orange Island lengthens and gets wider, the Gulf Trough is shallower and more narrow.
The Chipola Subsea from the Burdigalian through Langhian development of Florida.
Pliocene - Pleistocene Florida displaying the remnants of the Jackson Subsea heading toward post-Jackson dry period.