These facts link "Eritherium "with other early Proboscideans. "Prodeinotherium" was slightly smaller than "Deinotherium", yet much larger than more primitive proboscideans. This primitive mammalian dentition is unique among Proboscideans. They clearly diverged from the rest of the proboscideans at a very early date. This indicates that, like other proboscideans, deinotheres evolved in Africa. Some proboscideans developed tusks from their lower incisors. Several species of proboscideans lived on islands and experienced insular dwarfism. Many rodents grow larger on islands, whereas carnivorans, proboscideans and artiodactyls usually become smaller. These animals were very widespread and successful proboscideans. This group was formerly classified with proboscideans. The selenodont molars and vestigial third incisors are traits shared with paenungulates and proboscideans, respectively. Pneumatized skulls are also found in larger proboscideans (e.g. elephants, mastodons, and other extinct relatives). The classification of proboscideans is unstable and has been frequently revised. It and other anthracobunids were formerly classified with proboscideans. Stegolophodon is an extinct genus of proboscideans, with two tusks and a trunk.