The Journal of Mammalogy in Vol. 11, No. 3 (Aug., 1930), pp 300-303 included this introduction describing the work done in Idaho:
A NEW PLIOCENE HORSE FROM IDAHO
BY JAMES W. GIDLEY
Late in the summer of 1928, the U. S. National Museum received a few small lots of fossil bones from the Snake River Valley, Idaho, collected by Dr. Harold T. Stearns in connection with his work on ground-water resources. These and the reports sent in by Doctor Stearns gave such promise of a profitable collecting field that the Smithsonian Institution sent an expedition there the following summer (1929). This expedition obtained additional collections of considerable interest and value. By far the most important lot collected consisted of a quantity of well preserved fossil remains of an extinct species of horse belonging to the rare genus Plesippus. These specimens came from a fossil bone deposit in the vicinity of Hagerman, Idaho. The credit of discovery of this deposit goes to Mr. Elmer Cook, a resident of Hagerman, Idaho, who reported it to Dr. Stearns. The Smithsonian party collected here a quantity of well preserved material all pertaining apparently to a single species of horse. This material includes several skulls and jaws and numerous bones of all parts of the skeleton, representing ages ranging from young colts to old adults of both sexes.
Once the excavated fossil material was removed it was sent to Washington, DC, by train. The fossils needed to be extracted from the rock, which is the job of the fossil preparator. For the Smithsonian, at this time, that was most often Norman H. Boss. Boss was one of the first preparators to do prep work in public, answering questions and displaying his skill at the Texas Centennial Exposition in 1936.
Boss also did field work, leading the Smithsonian excavation at Hagerman in 1931 due to Gidley being ill. Boss was in Hagerman just two months, yet shipped 37 cases totaling 8,332 pounds, containing four more or less complete partly articulated skeletons, 32 skulls, 48 jaws, and a “vast number of bones representing all parts of the skeleton.”
Smithsonian Horse Fossil Distribution
(Notes from a Smithsonian article of September 2015)
In the late 1920s and early 1930s, field expeditions to Idaho from the Smithsonian yielded a large cache of fossils, some of which were used in trades. Gidley and Cook collected fossils in Hagerman in both 1929 and 1930, with three tons of specimens sent to the Smithsonian in 1929 alone.
The Smithsonian had more horse fossils than it needed for research or exhibit at the time. They decided to trade with other museums that did not have horse fossils. Smithsonian archives contain letters detailing offers of, and requests for, fossil horse skeletons and skulls. The Colorado Museum of Natural History traded a skeleton of Equus simplicidens for a skeleton of the early rhinoceros Trigonias osborni around 1931, and a 1932 exchange with the Los Angeles County Museum of History, Science and Art was worth a Pleistocene horse, Equus occidentalis. In 1933, an exchange with the Royal Ontario Museum brought skulls of the Late Cretaceous dinosaurs Prosaurolophus maximus (USNM 12712) and Edmontosaurus regalis (USNM 12711) from Alberta in exchange for horse fossils. A complete fossil horse skeleton, eight skulls, and five months of Charles W. Gilmore's time was deemed equal to a partial skeleton of the Late Jurassic dinosaur Camarasaurus from the Carnegie Museum of Natural History in Pittsburgh in 1935.
Last updated: August 17, 2019