Willow H. Nguy1, Jacalyn M. Wittmer1, Sam W. Heads2, M. Jared Thomas2 1Department of Geology, University of Illinois at Urbana-Champaign, 605 East Springfield Avenue, Champaign, Illinois 2 61820; Illinois Natural History Survey, University of Illinois at Urbana-Champaign, 1816 South Oak Street, The bones are beautifully preserved, but exhibit the typical preservation The rediscovery of an exceptional fossil bone bed from a Champaign, Illinois 61820 techniques of the times. The bone bed was excavated upside-down and then condemned university building has led to a revival of vertebrate covered in thick layers of shellac which discolors and becomes brittle over paleontology in the Department of Geology at the University of time. The entire specimen was then plastered into a mount. Both plaster Illinois Urbana-Champaign. This has been realized through a and shellac are damaging to the fossil and required that the fossil be conservation effort for the historically significant specimen and Cranium 2 and conserved quickly. a paleobiological study. The specimen was collected over fifty Side C mandible 2 years ago by Harold R. Wanless from an unspecified Miocene Steps to Preparation locality near Agate Springs, Nebraska. No other information was 1. Matrix is fully removed and bone is carefully lifted out of bone bed included in notes or on the display label. 2. Shellac is dissolved with acetone or ethanol 3. Softened shellac is removed in layers with dental picks and toothbrushes 4. Broken pieces are repaired with Paleobond PB100 5. Internal structure is strengthened by PaleoBond PB002- penetrant stabilizer 6. Cavity mount is made out of Ethafoam to safely and securely hold the curated specimen. Mandible 3 Mandible 1 Fig. 1. Cross-sectional view of Side A of bone bed. Scale in cm. It is interesting that the bones seem to have no preferred orientation, Side D but follow a general size gradation. Side B Cranium 1 Fig. 7. Left mandible 3 before conservation. Scale in cm. Photo courtesy: M. Jared Thomas Side A Fig. 2. Cross-sectional view of Side B of bone bed. Scale in cm. The matrix Fig. 5. Overview of bone bed with main bones identified Scale in cm surrounding the bones is a poorly consolidated, medium grained, quartz sand. Fig. 8. Left mandible 3 after conservation. Scale in cm. The Agate Springs Quarry, the locality near which this specimen was likely found, is from the Upper Harrison Formation (Miocene). These beds are “lithic pebble conglomerates, calcareous ashy sandstones, limestones, and This project will lead to technical descriptions of the partial cranium massive sands” (Hunt, 1978). This was a and the more complete skull. The fossils will be measured and compared to others of their species. Their teeth will be examined to fluvial environment and was likely frequented Photo courtesy: google earth by the rhinos and other large mammals. analyze their diet, definitive age, and lifestyle. This will improve our Fig. 3. Location of Agate Fossil Beds in knowledge of the paleobiology of Menoceras. Menoceras was a herding rhinoceros moving Nebraska. Map from Google Earth. in very large groups. They were drawn to Acknowledgments water and areas of plentiful food . These This project made possible with support by the University of Illinois Geology Department rhinos were smaller than modern Undergraduate Research Committee and the Illinois Natural History Survey. rhinoceroses and had paired horns. References In an extreme drought, the Menoceras herd Fig. 6. Close up view of cranium 1 and of cranium 2 with mandible 2. Scale in cm. These rhinoceroses are affectionately dubbed www.fossilworks.org lost thousands to malnutrition and “Cookie” and “Biscuit,” respectively. dehydration (NPS). As the water returned, the Hunt, Robert M. Jr., 1978. Depositional setting of a Miocene mammal assemblage, Sioux County, Nebraska Ongoing analysis has revealed that the hash contains at least two sub-adult female (U.S.A.). Paleogeogr., Paleoclimatol., Paleoecol., 24: 1-52 remains were hydrologically transported and Menoceras arikarense and a third unidentified individual. This has been suggested by the Mihlbachler, Matthew C., 2007. Sexual dimorphism in a small miocene North American Rhino, Menoceras sorted. This massive event produced the thick arikarense: insights into the coevolution of sexual dimorphism and sociality in rhinos. J Mammal Evol. Photo courtesy: Scott, 1913 historical and geological context of the fossils (Prothero, 2005) and original information. bone bed at Agate Fossil Beds today. 14: 217-238 Fig. 4. Horsfall’s (Scott, 1913) artistic Menoceras is sexually dimorphic- the males have raised “bosses” on their noses www.nps.gov/agfo/index.htm rendition of Menoceras. (Mihlbachler, 2007). The lack of the excess bone growth suggests that both skulls are female. The more complete skull has an un-erupted molar that indicates an immature Prothero, Donald R., 2005. The Evolution of North American Rhinoceroses. rhinoceros. Scott, W. B., 1913. A history of land mammals in the western hemisphere. .