PASADENA, California, Aug. 9 -- The California Institute of Technology issued the following news: Julia Tejada, a newly arrived assistant professor of geobiology at Caltech, is an explorer of the past. When she is not hunting for fossils in the Amazon, she is pioneering laboratory techniques to study the biochemistry of ancient bones. Tejada's research aims to understand the flora and fauna that populated the earth millions of years ago, on timescales that paleontologists and geologists call " more PR