In conjunction with their Cultural History studies, Ross School third graders immersed themselves in the world of paleontology. They looked at what can be determined from the fossil evidence of dinosaurs, early mammals, and plants about ecosystem dynamics before the K-T extinction, which occurred at the end of the Mesozoic Era. They researched the current hypotheses about what caused the mass extinction of dinosaurs. Throughout this unit of study, the students assumed the role of paleontologists as they researched, interpreted, and pieced together the fossil evidence. They determined that biology and geology are, indeed, co-evolving systems. The goal of the ongoing dig is to identify different methods paleontologists use to determine prehistoric history.