Felch collected a disarticulated partial skull (USNM V 5730) of a sauropod in August 1883 and sent the specimen to Yale. Marsh referred the skull to B. excelsus, later featuring it in a skeletal reconstruction of the B. excelsus type specimen in 1891 and the illustration was featured again in Marsh's landmark publication, The Dinosaurs of North America, in 1896. At the Yale Peabody Museum, the skeleton of Brontosaurus excelsus was mounted in 1931 with a skull based on the Marsh reconstruction of the Felch Quarry skull. While at the time most museums were using Camarasaurus casts for skulls, the Peabody Museum sculpted a completely different skull based on Marsh's recon. The skull also included forward-pointing nasals, something truly different to any dinosaur, and fenestrae differing from the drawing and other skulls, and the mandible was based on a Camarasaurus'. In 1998, the Felch Quarry skull that Marsh included in his 1896 skeletal restoration was suggested to belong to Brachiosaurus instead and this was supported in 2020 with a redescription of the Brachiosaurid material found at Felch Quarry. Second Dinosaur Rush and skull issue During a Carnegie Museum expedition in 1901 to Wyoming, William Harlow Reed collected another Brontosaurus skeleton, a partial postcranial skeleton of a young juvenile (CM 566), including partial limbs, intermingled with a fairly complete skeleton of an adult (UW 15556). The adult skeleton specifically was very well preserved, bearing many cervical and caudal vertebrae, and is the most complete definite specimen of Brontosaurus parvus. The skeletons were granted a new genus and species name, Elosaurus parvus ("little field lizard"), by Olof A. Peterson and Charles Gilmore in 1902. Both of the specimens came from the Brushy Basin Member of the Morrison Formation. The species was later transferred to Apatosaurus by several authors until it was placed in Brontosaurus in 2015 by Tschopp et al. Elmer Riggs, in the 1903 edition of Geological Series of the Field Columbian Museum, argued that Brontosaurus was not different enough from Apatosaurus to warrant its own genus, so he created the new combination Apatosaurus excelsus for it. Riggs stated that "In view of these facts the two genera may be regarded as synonymous. As the term 'Apatosaurus' has priority, 'Brontosaurus' will be regarded as a synonym". Nonetheless, before the mounting of the American Museum of Natural History specimen, Henry Fairfield Osborn chose to label the skeleton "Brontosaurus", though he was a