The Proboscidea is the Order of mammals that includes the elephants, mastodons, and their closest relatives. Phiomia represents one of the earliest members of the group, though anatomically it was already developing some similarities to its later relatives. These features include the lengthening of the head as well as the development of large open nasal cavities that would house muscles to a large proboscis. Phiomia was about the size of a cow; a large animal, but still relatively small in comparison to later Proboscideans. The long lower jaw tapered into a spade-like shape similarly to the Amebelodonts, and the animal may have used it like a wedge to snap off branches from trees, or to clear away marshy terrain. Phiomia lived from the Late Eocene to the Early Oligocene; in the tropical coastal forests that will eventually become Egypt.