Hemiauchenia

Superregnum: Eukaryota
Cladus: Opisthokonta
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Tetrapoda
Classis: Mammalia
Subclassis: Theria
Infraclassis: Placentalia
Superordo: Cetartiodactyla
Ordo: Artiodactyla
Subordo: Tylopoda
Familia: Camelidae
Genus: Hemiauchenia

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Hemiauchenia [1] 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 went 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.[2]

Distinguishing characteristics of members of Hemiauchenia

vera:
• Relatively low-crowned teeth
• 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. paradox, H. seymourensis, H. edensis and H. guanajuatensis. According to which source is consulted, these may or may not be considered legitimate taxa.

References

1. ^ Paleobiology Database - Hemiauchenia basic info
2. ^ Ruez, D. R. (2005-09-30). "Earliest Record of Palaeolama (Mammalia, Camelidae) with Comments on "Palaeolama" guanajuatensis". Journal of Vertebrate Paleontology (Society of Vertebrate Paleontology) 25 (3): 741–744. http://www.jstor.org/pss/4524496. Retrieved 2009-10-24.

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)