Hemiauchenia

Hemiauchenia Temporal range: Miocene - Pleistocene, 10–0.010 Ma PreЄ Є O S D C P T J K Pg N
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Fossil maxilla of Hemiauchenia cf. paradoxa
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Artiodactyla
Suborder:	Tylopoda
Family:	Camelidae
Tribe:	Lamini
Genus:	†Hemiauchenia Gervais & Ameghino, 1880
Species
H. macrocephala (Cope, 1893) H. minima (Leidy, 1886) H. blancoensis (Meade,1945) H. vera (Matthew, 1909) H. paradoxa (Gervais & Ameghino, 1880)

Hemiauchenia is a genus of lamine camelids that evolved in North America in the Miocene period approximately 10 million years ago. This genus diversified and moved to South America in the early Pleistocene as part of the Great American Interchange, giving rise to modern lamines. The genus became extinct at the end of the Pleistocene.

Remains of these species have been found in assorted locations around North America including: Florida, Texas, Kansas, Nebraska, Arizona, Mexico, California, Oklahoma, New Mexico, Colorado and Washington. The "large-headed llama", H. macrocephala, was widely distributed in N. and Central America, with H. vera being known from the western U. S. and northern Mexico. H. minima has been found in Florida, and H. guanajuatensis in Mexico.

Distinguishing characteristics of members of Hemiauchenia

vera:
• Relatively low-crowned teeth (part of visible teeth ends close to gums)
• Large caniniform upper P1
• Retention of lower P3

blancoensis:
• Shorter mandibular diastema than macrocephala but shorter than vera
• Canniform upper P1
• Absent P2
• Upper P3 present or absent
• Lower crowned molars

macrocephala:
• Long, robust limbs
• Large skeletal size
• Presence of a deciduous upper P2
• Fully molariform deciduous P2
• High-crowned molars
• Thick layer of cementum on the teeth
• Broad mandibular symphasis with incisors in a vertical fashion

minima:
• Despite being the earliest recognized species, general distinguishing characteristics for H. minima are little known.

There are also a few lesser known species such as: H. paradoxa, H. seymourensis, H. edensis and H. guanajuatensis. According to which source is consulted, these may or may not be considered legitimate taxa.

References

• 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).
• Meachen, Julie A. "A New Species of Hemiauchenia (Camelidae;Lamini) From." Diss. University of Florida, 2003. Abstract. Web. <http://etd.fcla.edu/UF/UFE0000965/meachen_j.pdf>.
• 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)