I have recently published a book on paleontological subject named:

Los selaceos fòsiles de la localidad de Alto Guayacán y otros
ictiolitos (= Chondrycthyes and other ichtyolites from the Alto
Guayan locality), this book contains information about Upper Miocene
costarican's paleontological locality. It discribes around 39 species
of sharks and rays, six of them are new for the science. On the other
hand it expouses aditional stratigraphical and paleobiogeographical
correlations with other localities of the Caribbean, North American
Coastal plaind, Gulf of Mexico and other world's Miocene localities.

You can order a copy of the book


Dr. César Laurito Mora