Among the most rare and challenging discoveries for any paleontologist are the early mammals that arose in the shadows of the great beasts of the Mesozoic. Few fossil mammals have survived the ravages of geologic history, and those that have are supremely difficult to find and collect. Most of what we know of the earliest mammals comes from a few fragmentary teeth and jaws, which, because of their durable mineral composition, tend to remain intact when other bones have crumbled.

Despite these challenges, Carnegie Museum of Natural History Associate Curator of Paleontology Zhe-Xi Luo, PhD, is forging ahead with some of the most important research in the field. In the past two years, Luo has been involved in two of the most significant discoveries in mammalian evolution, and his recent research on Jeholodens jenkinsi, published in the March 25, 1999, issue of Nature is helping to piece together a dark era in evolutionary history, shedding new light on the origin and interrelationships of early mammals.