Othniel Charles Marsh
New specimens were not described for many years following the activity of the early 1900s. In 1964 John Ostrom noted that an old species named by Othniel Charles Marsh, "Hadrosaurus paucidens", based on USNM 5457, a partial maxilla and squamosal from the Judith River Formation of Fergus County, Montana, was probably a specimen of "Lambeosaurus".