James W. Gidley (1866-1931), vertebrate paleontologist and museum curator, was born in Springwater, Iowa. He developed an early interest in paleontology, collecting fossils in the Black Hills near his boyhood home. In 1892, Gidley was appointed Assistant in Vertebrate Paleontology at the American Museum of Natural History (AMNH). He remained at the AMNH until 1905, although the continuity of his service was broken while he pursued his formal education. He received the B.S. degree in 1898, and the M.S. degree in 1901 - both from Princeton University. He earned his Ph.D from George Washington University in 1922. Perhaps his most important work for the AMNH was a series of field explorations to collect fossil horses. During these trips, Gidley discovered the fossil horse Equus scotti in Texas in 1899. This discovery was the subject of his first published paper the following year. Gidley also collected a new genus of three-toed horse, Neohipparion, in Nebraska in 1902.
Gidley's career at the United States National Museum (USNM) began in 1905 when he was appointed Preparator in the Section of Vertebrate Fossils. In 1908, he was promoted to Custodian of Fossil Mammals in the newly created Division of Vertebrate Paleontology. He was made Assistant Curator in 1912, and remained in that position until his death.
Gidley's career at the USNM was marked by several field explorations to collect fossil mammals. Included were trips to Maryland, Indiana, and Arizona. In the mid 1920s, he began a series of explorations around Melbourne and Vero Beach, Florida, in search of Pleistocene man. Gidley's research interests were varied and he pursued studies of fossil mammals ranging from rodents to the horse. His bibliography listed 87 titles and included brief reports on the identity of specific specimens, as well as detailed studies of certain mammalian groups.