Makaira panamensis new sp. is described from a single neurocranium found in the Chagres Sandstone (Late Miocene) of the Atlantic coast of Panama. The new species is closely related to and possibly ancestral to the extant M. indica (black marlin) and M. nigricans (blue marlin). It differs from both by possessing a triangular rather than elongate basioccipital foramen, large nutrient canals in the rostrum and probably a more elongate orbit. The fossil is compared to all known fossil Istiophorids as well as to the living marlins. It is suggested that the black marlin is a more recent derivative (than the blue marlin) that was unable to thrive in the Atlantic Ocean because of a temperature barrier
