A New Species of Hemiauchenia (Artiodactyla, Camelidae) from the Late Blancan of Florida

Abstract

A new species of lamine, Hemiauchenia gracilis n. sp., is present at six late Blancan fossil localities in Florida: Inglis 1A and 1F in Citrus County; DeSoto Shell Pits 1 and 5 in DeSoto County; Santa Fe River 1 in Columbia County; and Waccasassa River 9A in Levy County. The fossil deposits at these locations are thought to be between 1.8 and 2.5 million years old. The holotype specimen is a right mandibular fragment including p4 through m3. Hemiauchenia gracilis lacks p1 through p3. The teeth of H. gracilis are similar to those of Hemiauchenia macrocephala and Hemiauchenia edensis, with an intermediate crown height and a small degree of crenulation. Postcranial elements of H. gracilis are very long and slender, especially the radio-ulna and the phalanges, apparently adaptations for cursoriality. Stable carbon isotope data for H. gracilis show a mixed-feeding signature, with more browse than grass. A phalanx with the size and proportions of those of H. gracilis was found at the late Pliocene 111 Ranch, Graham County, Arizona. This would potentially extend its range as far west as Arizona, drawing it closer toward Mexico and Central America, and possibly giving insight into the origin of the extant Lamini.