A Paleontological Review of Three Billfish Families (Istiophoridae, Xiphiidae, and Xiphiorhynchidae)

In 1974, I summarized the osteological and paleontological knowledge of billfishes and suggested some areas of research to aid future paleontological studies (Fierstine 1974). My suggestions included: (l) a comparative osteo­ logical study, especially of the rostrum, in order to obtain more accurate identifications of fos­ silized material; (2) a functional study of the feeding mechanism, in order to explain observed interfamilial differences in the skull; (3) a func­ tional study of the locomotor apparatus in order to elucidate interand intrafamilial differences in vertebrae, body shape and fin morphology, and (4) a more thorough study of those extinct families (Blochiidae and Paleorhynchidae) and genera (Acestrus and Brachyrhynchus) having uncertain affinities to other billfishes. Since 1974, some of the foregoing items, as well as some not listed, have been studied with varying degrees of thoroughness. In the most comprehensive treatise, Schultz (1987) investi­ gated all extant and extinct billfishes and developed a new taxonomic arrangement and evolutionary scheme based primarily on structure of the rostrum. The present study reviews the published accounts, presents some new informa­ tion, and summarizes the relevant osteological and current paleontological knowledge of three billfish families (lstiophoridae, Xiphiidae, and Xiphiorhynchidae) .