Ischyromys This is an extensive morphometric project in which 127 measurements were made on over 5, 000 fossil dentaries of the Eocene-Oligocene rodent Ischyromys. This was the subject of my Ph.D. dissertation at Harvard University and several subsequent publications. Ph.D. Thesis on Ischyromys. Ischyromys of the Great Plains published in the Journal of Paleontology. Ischyromys of Badlands ...