Last week, I visited the Division of Fossil Primates at the Duke Lemur Center in Durham, North Carolina. They have a great collection of fossil proboscideans from Egypt, including early forms like Moeritherium and Paleomastodon, as well as later, larger species such as Gomphotherium angustidens.I was there especially to see four teeth, the only known fossils of Zygolophodon aegyptensis. The genus Zygolophodon is long-lived and widespread, including many other species from Europe, Asia, and North America. At about 18 million years old, Z. aegyptensis is among the oldest. Zygolophodon is a member of the group Mammutidae, making it a close relative of North America's mastodons, including those found at Diamond Valley and housed at Western Science Center.The image here is DPC 12598, an upper molar (right M3) of Zygolophodon aegyptensis, and a left M3 of a mastodon from Diamond Valley (WSC-P-9970) set to the same scale. My Western Science Center colleagues and I are working with paleontologists at several other institutions to explore the whole evolutionary history of Mammutidae. Visiting other museums to examine fossils of other species and comparing them to the bounty of mastodons from Diamond Valley is one of the first steps on this journey.My thanks to Catherine Riddle of the Division of Fossil Primates for her assistance during my visit.Post by Curator Dr. Andrew McDonald.