Published in Journal of Vertebrate Paleontology, Volume 19, Issue 3, September 1, 1999, pages 430-437. Copyright © 2005 Society of Vertebrate Paleontology. Journal webpage: http://vertpaleo.org/publications/JVPContent.cfm.
A nearly complete rostrum (USNM 358534) similar in morphology to the extant bluc marlin, Makaira nigricans Lacepede 1802, is identified from the GaUln Formation (late Miocene, Panama). Identification is based on comparison with a large series of Recent istiophorid species and with fossil species of the genus Makaira. The Gatlin specimen and additional examples from other fossil vertebrates provide evidence that the ancient Panama Seaway probably was a travel route between the Atlantic and Indo-Pacific for large marine vertebrates during the middle Miocene to earliest Pliocene. This is the first record of an istiophorid billfish from the Gatlin Fonnation and the second record of a fossil marlin from Panama.