After a few weeks of focusing on mastodon remains, it's worth remembering that there were two different species of proboscideans at Diamond Valley Lake. While mastodon remains are quite common, Columbian mammoths (Mammuthus columbi) were also present.This specimen is a lower left 1st or 2nd molar of M. columbi, discovered during the early years of the DVL excavations. Like the closely related Asian elephant, mammoths had enamel that is folded multiple times, wearing to produce a series of raised transverse enamel ridges in occlusal view. Like other advanced proboscideans mammoths replaced their teeth sequentially, so the front of the tooth (on the right in the image above) is more heavily worn that the back of the tooth. In fact, the last enamel ridge is essentially unworn, so this tooth had probably not quite completely erupted.A cast of this tooth is on permanent exhibit at the Western Science Center, as a touchable display allowing visitors to compare the very different occlusal surfaces of mammoth and mastodon teeth. As it happens, we're also auctioning off an additional cast of this tooth (below) tomorrow night at our annual Science Under the Stars fundraiser.