Fossil frogs (Eleutherodactylidae: Eleutherodactylus) from Florida suggest overwater dispersal from the Caribbean by the Late Oligocene

Abstract

Establishment of extant terrestrial vertebrate faunas in North America was influenced by a set of factors associated with temporal changes in climate and ecology that operated at different geographic scales. While the biogeography of extant taxa can be inferred from phylogenies, these omit lineages that have gone regionally extinct and for which the only direct evidence is the fossil record. A comprehensive study of anurans from the Late Oligocene of Florida reveals an abundance of fossils referred to Eleutherodactylus. Time-calibrated molecular phylogenies have suggested that this genus originated in the Caribbean in the Early Oligocene and then colonized Central America in the Middle Miocene. Here, we describe the first records of pre-Quaternary fossils referred to Eleutherodactylus from Florida. Results from analysis of inter- and intraspecific variation in anatomy, size, and shape of isolated bones of fossil and extant species suggest that the fossils represent adult individuals with an estimated body size (snout–urostyle length) of 16.8–29.8 mm. We show that Eleutherodactylus was established by the Late Oligocene in North America well before colonizing Central America in the Miocene. We provide, for the first time, evidence of dispersal of amphibians from the Caribbean into North America during the Late Oligocene.