The geological history of octopus is virtually unknown, owing to lack of a preservable skeleton. Several octopod species today are known to drill holes in prey animals for the injection of venom. These borings are incipient trace fossils that have good fossilization potential, and are named Oichnus ovalis isp. nov. Their abundance in Pliocene assemblages suggests that the will be recognized elsewhere in Tertiary and perhaps older assemblages, providing greatly needed data on the earlier range and feeding habits of octopus.