PHILADELPHIA Two former students have named a 75-million-year-old frog species in honor of vertebrate paleontologist Peter Dodson of the University of Pennsylvania.

Dating to the Cretaceous era, the newfound species, Nezpercius dodsoni, also commemorates the Nez Perce tribe of Native Americans. The fossil frog was unearthed in central Montana, near where the tribe crossed the Missouri River as it was pursued toward Canada in 1877.

Dodson, professor of anatomy in Penn School of Veterinary Medicine and professor of earth and environmental science in Penn School of Arts and Sciences, also conducts fieldwork in Montana as well as Egypt, China and Argentina as part of his studies of dinosaur remains.

The honor came as a surprise to Dodson, who first learned of it while reading a paper in the March issue of the Journal of Vertebrate Paleontology that described the newfound species.

The paper indicates that the "species name honors Peter Dodson for his contributions to paleoecological research in the Judith River Formation."

Richard W. Blob, one of the paper five authors, is a 1992 Penn graduate who did fieldwork with Dodson in Montana for several years. He is now a postdoctoral researcher at the Field Museum of Natural History in Chicago.

Another author, Catherine A. Forster, was a doctoral student under Dodson, receiving her Ph.D. in 1990. She is now associate professor of anatomy at the State University of New York at Stony Brook.

"It was a pleasure to name the species after Peter," Blob said. "We all agreed that he very much deserved the honor."