Hemiauchenia

Mammalia; Artiodactyla; Camelidae; Hemiauchenia macrocephala (llama)

Hemiauchenia macrocephala, (large-headed llama) is a late Pleistocene llama that was recovered in a fissure fill deposit in Florida. This fossil species of llama was long-legged, standing nearly two meters high at the shoulder. The specimen shown here is pristinely preserved and unique in that the vast majority of the bones are from a single individual, a rarity in the Florida fossil record. The Hemiauchenia lineage, although now extinct, extends back into Florida's Miocene record, some 9 million years ago. It is one of the earliest known llamines and one of the largest ever recovered.

Life History

Living members of the camel group include two species of Old World or true camels (those with humps), the Dromedary (1 hump) and the Bactrian (2 humps), and the New World camels, or llamas, which have no humps. All the members of this group have long thin necks, small heads, a 3-chambered stomach, and a cleft upper lip, a characteristic that may facilitate their notorious spitting habit.

Llamas, like their cousins the camels, are grazers that live in the arid high plains and deserts. On all four feet, they have two toes supported by a tough pad that provides them sure footing over a wide range of terrain. All camelids (camels + llamas) have a characteristic stride or "pace", whereby the legs on each side move in unison causing the body to sway from side to side so much so that camels are sometimes referred to as 'ships of the desert'.

Llamas live in family groups of up to 30 individuals that include a single adult male, numerous adult females, and their young. The young live within the family group until around 15 months of age when the alpha (dominant) male forcibly evicts them from the group. Llamas give birth to a single offspring every other year, with a gestation period of approximately 12-15 months. They are easily domesticated and have long been commandeered for pack animals, as well as for their fur, and hides. Llamas, unlike their true camel cousins, do not tolerate being ridden, thus they have never been used as a source of human transportation.

Evolutionary History

Camelids are members of the larger group of even-toed ungulates, the Artiodactyla. There are numerous characteristics that distinguish living camels and llamas from other artiodactyls (even-toed ungulates), the most unique characteristic is that they have oval-shaped red corpuscles, while all other mammals have round-shaped corpuscles. Camel and llama toes are decidedly splayed (divergent), and their foot bones (metapodials) are fused into a single bone, called the 'cannon bone'.

There are three living genera and six species in the Camelidae family. They include the Old World 'true camels', the Dromedary (single-humped) and Bactrian (two-humped) camels, and the four New World llamines; llamas, vicunas, alpacas, and guanacos. Llamines, or llamas, are distinguished from camels in that they lack a hump, they have more of a domed cranium which houses a larger brain then camels, and they have a distinct enamel "buttress" on their molars.

Camelids first appear in the fossil record in the middle Eocene of North America. From the first distinguishable fossil camelid (Poebrodon) through to the Recent forms, camelids have ranged in size from about 3 feet tall (Genticamelus), to approximately 17 feet tall at the head (Aepycamelus). Over 50 species have been recognized in the fossil record, although today only 6 species remain.

The most recent hypothesis of relationships within the Camelidae suggests that the true llamines (or llamas) include; [Camelops + Alforjas] + [Aepycamelus, Hemiauchenia, Paleolama, Lama, and Vicuna]. The earliest known llama is probably 'Hemiauchenia' minima from early late Miocene sediments (approximately 6-5 MA) in Florida.

Biogeographical History

Although true camels are considered Old World forms, they evolved and diversified in North America for most of their evolutionary history. Camels migrated over the Bering Straits Land Bridge into the Old World only 5-million years ago, some 40 million years after their first appearance in the fossil record. Llamas, now solely restricted to South America, also evolved in North America. They reached South America by crossing the Panamanian Land Bridge about 2-1.5 MA years ago, when it was newly formed. North American llamas and camels subsequently went extinct 11,000 years ago along with many other large mammals.

Today, llamas are found in the high plains (the Altiplano of the Andes Mountains) of South America, as well as in some areas of Paraguay. True camels are restricted to areas in northern China and the Arabian regions, however they are now mostly domesticated, with few wild populations left.

Conservation Efforts

Of the four species of llamas, the alpaca and the llama have been completely domesticated. In fact, there is some evidence to suggest that the Incas domesticated "llamas" some 4000-5000 years ago. There is even some evidence that these two species are actually hybrids! Since their domestication by the Incas, llamas have continued to be of economic important not only for their high quality fleece, but also as an important food source and pack animals.

The future for the guanaco and vicuna is not as secure as it is for the llama and alpaca. They remain wild and heavily hunted for not only their valuable skin, but also for their habitat, where sheep ranching has become well established. The guanaco is listed on Appendix 2 of CITES (Convention On International Trade In Endangered Species Of Wild Fauna And Flora), that is, it is internationally recognized that they will quickly become extinct unless measures are taken to oversee and regulate their populations. The current status for vicuna is somewhat brighter in that recent conservation efforts have resulted in an increase in the numbers of vicunas. Nevertheless, their fleece, in conjunction with governmental policies which still allow the exportation of this valuable cloth, continues to make vicunas subject to illegal poaching, which has contributed to its near extinction.

History of Specimen

This late Pleistocene skeleton of Hemiauchenia macrocephala (large-headed llama) is a remarkable specimen; the majority of the bones are from a single individual, it is more than 95% complete. This individual was discovered by an amateur paleontologist, Mr. Steve Beck, in a fissure-fill deposit in Citrus County, Florida in the early 1980's. Subsequently, this specimen was acquired by Stephen and Rena Jacobsen, who had it prepared and mounted. In 1999, the Jacobsen's generously donated the specimen to the FLMNH's Hall of Florida Fossils. To preserve the integrity of the specimen, the skull was cast, and the original was returned to the Vertebrate Paleontology collections at the FLMNH for further study.

Bibliography

Honey, J. H., J. A. Harrison, D. R. Prothero, and M. S. Stevens. 1998. Camelidae. pp. 439-462. In: Evolution of Tertiary Mammals of North America, Eds: C. M. Janis, K. M. Scott, and L. L. Jacobs, Cambridge University Press, Cambridge, United Kingdom. 691 pp.

Hulbert, R. C. 1992. A checklist of the fossil vertebrates of Florida. Papers in Florida Paleontology, no. 6:25-26.

Kurtén, B. and E. Anderson. 1980. Pleistocene Mammals of North America. Columbia University Press, NY, 442 pp. (camels - 301, 306-307).

McKenna, M. C. and S. K. Bell. 1997. Classification of Mammals above the Species Level. Columbia University Press, NY, 631 pp. (camels - pp. 413-416)

Nowak, R. M. 1999. Walker's Book of Mammals, vol. 1. Johns Hopkins University Press, Baltimore, pp. 837 - 1936. (camels - pp.1072-1081).