Fossils in Porcupine Cave

Don and Jerry Rasmussen took the fossils collected in 1981 to the University of Kansas the following year for comparison with the mammal collections there. With the help of Larry Martin and Robert (Bob) Hoffmann, professors of vertebrate paleontology and mammalogy, respectively, most of the mammals were tentatively identified. In 1984 Don gave the fossils to Peter Robinson, curator of vertebrate fossils at the University of Colorado Museum of Natural History, for study and possible curation. In May 1985, Don Rasmussen met in Denver with his friend Anthony D. (Tony) Barnosky, then of the Carnegie Museum of Natural History, and told him about the fossil finds in Porcupine Cave. At that time Barnosky, already familiar with cave faunas in the Appalachians, was interested in locating deposits that would similarly elucidate mammal response to climate change in the Rockies. Barnosky went to the cave for the first time with Rasmussen in September 1985, to collect a sample of bones and teeth to take back to the Carnegie Museum for radiocarbon dating and further study, with plans to return the following summer. The bones were found to be older than the 50,000-year limit of the dating process and thus attracted immediate interest.

Rasmussen contacted Frank McMurry, the owner of the cave, explained the possible significance of the cave as an important fossil site, and gained permission for paleontological excavations within the cave. Barnosky returned in July 1986 with his Carnegie field crew, collected specimens from differ ent parts of the cave, and began an excavation site in the Pit. Among the several hundred specimens collected, Barnosky later identified two extinct Irvingtonian (middle Pleistocene) rodents that lived at least half a million years ago (Barnosky and Rasmussen, 1988). This find indicated that the fauna in Porcupine Cave was much older than had been expected and sparked intense interest in the high-elevation Pleistocene fossils of Porcupine Cave—interest that continues today.

Local volunteers led by Don Rasmussen worked side by side in Porcupine Cave with the Carnegie Museum crews in the late 1980s. At the same time, Denver Museum volunteers led by Elaine Anderson were investigating the modern biota in the Porcupine Cave area. Carnegie Museum excavations in the cave ceased in 1990, by which time the work in the Pit, the Velvet Room, and a number of other localities in the cave had produced tens of thousands of specimens. This material was eventually curated into collections at the Carnegie Museum and the University of California Museum of Paleontology, Berkeley. Understanding the significance of the finds by Carnegie and the landowner's interest in keeping the fossils in Colorado, Rasmussen encouraged the Denver Museum of Nature and Science to become a repository for Porcupine Cave fossils in 1992. Led by Don Rasmussen until 1998, crews from the Denver Museum and Western Interior Paleontological Society continued excavations in the cave, especially in the Velvet Room; each field season produced new discoveries, which have been curated at the Denver Museum.

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