1. a División Paleontología de Vertebrados , Museo de La Plata , 1900 , La Plata , Argentina E-mail:
2. d Department of Biology , University of South Dakota , Vermillion , SD , 57069 E-mail:
3. b Department of Ichthyology , The Academy of Natural Sciences , 1900 Benjamin Franklin Parkway, Philadelphia , Pennsylvania , 19103 , U.S.A. E-mail:
4. c Instituto de Zoologia Tropical, Universidad Central de Venezuela , Apartado de Correos 47058, Caracas , 1041-A , Venezuela E-mail: