The climate 150 million years ago of a large swath of the western United States was more complex than previously known, according to new research from Southern Methodist University, Dallas. It’s been held that the climate during the Jurassic was fairly dry in New Mexico, then gradually transitioned to a wetter climate northward to Montana. But based on new evidence, the theory of a gradual transition from a dry climate to a wetter one during the Jurassic doesn’t tell the whole story, says SMU paleontologist Timothy S. Myers, lead author on the study.