John Harold Ostrom (February 18, 1928 – July 16, 2005) was an American paleontologist who revolutionized modern understanding of dinosaurs in the 1960s. As first proposed by Thomas Henry Huxley in the 1860s, Ostrom showed that dinosaurs were more like big non-flying birds than they were like lizards (or "saurians"), and even proved that birds themselves are a type of theropod saurischian dinosaur. Since dinosaurs themselves are considered reptiles, Ostrom's work made zoologists question whether birds should be considered an order of Reptilia instead of their own class, Aves. The first of Ostrom's broad-based reviews of the osteology and phylogeny of the primitive bird Archaeopteryx appeared in 1976. His reaction to the eventual discovery of feathered dinosaurs in China, after years of acrimonious debate, was bittersweet. Early life and career Ostrom was born in New York in 1928 and grew up in Schenectady. As a pre-medical undergraduate student at Union College, he originally aimed to prepare for medical school in order to become a physician like his father. However, an elective course in geology and George Gaylord Simpson's book The Meaning of Evolution inspired him to change his career plans, and he earned his bachelor's degree in geology in 1951. As an undergraduate and then as a research assistant during the 1950s, he learned about vertebrate paleontology from Simpson and Edwin H. Colbert at the American Museum of Natural History. Ostrom enrolled at Columbia University as a graduate student under his advisor Ned Colbert, and earned his Ph.D. in 1960 with a thesis on North American hadrosaurs that was based on the skull collection housed at the AMNH. In 1952 he married Nancy Grace Hartman (d. 2003) and they had two daughters, Karen and Alicia. Ostrom taught for one year at Brooklyn College in 1955 before joining the faculty at Beloit College the following year. In 1961 he accepted a professorship at Yale University, where he remained throughout his career. As a new professor at Yale, Ostrom was named the assistant curator for vertebrate paleontology at the Peabody Museum of Natural History, and became Curator Emeritus in 1971. Throughout his career, Ostrom led and organized fossil-hunting expeditions to Wyoming and Montana, edited the American Journal of Science, published over a dozen books for both popular and lay audiences, and was the recipient of numerous awards and honors. He retired from Yale in 1992, but continued his writing and research there