OLIGOCENE VERTEBRATE FAUNAS FROM PUERTO RICO
The early Oligocene faunas include elasmobranches, osteichthyans, anurans, podocnemidid turtles, gryposuchine gavialoid, megalonychid sloths, caviomorph rodents and dugongid sirenians. The elasmobrances, osteichthyans and sirenians include taxa that are known from Eocene (Jamaica and Cuba) and/or Miocene (Panama, Cuba, Venezuela) deposits throughout the Cenozoic of the Caribbean region. The Oligocene age of the fauna studied here serves as a link between these two periods showing that the marine vertebrate fauna of the Caribbean region can be considered as a single faunal region with little overall change through the Cenozoic.
Other members (i.e. megalonychid sloth and caviomorph rodents) of the early Oligocene fauna represent taxa with strictly South American affinities; which is consistent with the landspan hypothesis for the origins of the fauna. Others, such as the gryposuchine gavialoid and possibly the podocnemidid turtles, likely used this landspan to disperse southwards to the South American landmass. The new finds reported here as underline the importance of paleontological and geological research in Oligocene age deposits to further understand the origins of the Greater Antillean vertebrate fauna.