A large fossil skull and several rostra of Makaira nigricans Lacépède, 1802 (Perciformes: Istiophoridae), as well as some less diagnostic istiophorid remains, have been recovered from the middle facies of the Trinidad Formation near Rancho Algodones, San José del Cabo Basin, Baja California Sur, México. These are the only bill fish specimens known from fossiliferous deposits located between southern California and Panama. Based on published accounts of the presence of nannofossils and planktonic foraminifera, and additional field work, we conclude that the age of the study area is late Miocene to late Pliocene. Based on the habitat preferences of recent M. nigricans and on the type of sediments, we conclude that the middle facies of the Trinidad Formation was deposited far offshore at a water depth of at least 100 m in a bottom environment that was poorly oxygenated and without currents.



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