One of the most important ancient discoveries in the history of California It was first discovered by looking at half a tree buried in the mud of the Mokelom River Basin in the valley of Sierra Nevada. Walking through the Allen Valley last summer San Francisco East Bay Municipal Service District (EBMUD) Ranger Greg FrankIt attracted attention. Frank later began to study further, leading to some of the most important fossil discoveries in California history. Franks travels from different parts of the country to examine the bones. Paleontology And Geology Approached their experts. Even today, the team continues to excavate to find the remains of ancient animals.