Bonnethead began with a taxon that had a highly pronounced cephalofoil (most likely that similar to the winghead shark, "Eusphyra blochii"), and was later modified through selective pressures. Thus, judging by their smaller cephalofoils, bonnethead sharks are the more recent developments of a 25-million-year evolutionary process. This species occurs off the American coast, in regions where the water is usually warmer than . It ranges from New England, where it is rare, to the Gulf of Mexico and Brazil, and from southern California to Ecuador. During the summer, it is common in the inshore waters of the Carolinas and Georgia; in
Creature Catalogue found in the Basic, Expert, Companion and Master rulesets. Each creature in the book is illustrated, and the entries in the book are ordered by type rather than just alphabetically. This includes six sections: Animals (including giant and extinct varieties), Conjurations (such as elementals and golems), Humanoids, Lowlife (including insects, plants, and jellies and slimes), Monsters (a catch-all category), and Undead. The Intelligence score of each monster is listed with the rest of its statistics. The book also includes a comprehensive index of all monsters by environment, and Frank Mentzer's guide on how to balance encounters according to the levels