An island once existed that is now Florida. The island had a fifty mile radius between present day Tampa and Orlando. Only recently have scientist discovered this fact. It took phosphate mining to uncover this.
In the 1920's companies began mining for phosphate in Polk County. They began to find very large bones. Strange bones. In fact, they found teeth for every kind of shark known on Earth. Woolly Mammoth, saber tooth tiger, rhinoceros, giant ground sloths and all the post ice age creatures were found here in great concentration. The find was so large, they now call it "bone valley."
Near the end of the last ice age, sea water poured back into central Florida and the higher ground (only 300 feet above sea level) formed an island for the next 10,000 years. The ice age creatures could not migrate north, so they stayed here until the water receded. Most of them died before that happened.
Last year I went to the "cryptozoological" museum in Mulberry Florida. The fossils they had on display will blow your mind.