1. Department of Earth Sciences, Montana State University, Bozeman, MT 59717, USA.
2. Department of Geology and Geophysics, Texas A&M University, College Station, TX 77843, USA.
3. Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA.
4. Division of Paleontology, American Museum of Natural History, New York, NY 10024, USA.
5. Department of Mathematical Sciences, Montana State University, Bozeman, MT 59717, USA.