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Extinct Large-headed Llama (Hemiauchenia macrocephalus) Fact Sheet: Taxonomy & History

Extinct Large-headed Llama (Hemiauchenia macrocephalus)

How Do We Know This?

Like living animals, fossil remains of once-living animals are classified and grouped according to their relationships to each other and to their ancestors.

Taxonomy and Nomenclature

  • Several researchers have re-established the validity of this species after it was earlier synonymized. (Honey et al 1998)
  • Some taxonomists have questioned the validity of Hemiauchenia paradoxa in South America, but recent studies have helped distinguish this species from other camelids. (Scherer 2007)

Evolutionary History

  • The camelid family began in North America some 46 million years ago in the Eocene Epoch. (Whistler and Webb 2005)
    • Sheep-sized Probrotherium is the most primitive camel-like ancestor. (Janis et al 2002)
  • A drying trend that produced the first areas of true savanna in North America coincided with the rise of camels. (Webb 1977)
  • A small camel, Miotylopus, lived in southern California, around 28 million years ago.
  • New DNA studies reveal that the two camel family tribes separated around 25 million years ago, much earlier than previously believed. (Cui et al 207)
  • Between 20 and 14 million years ago, some 13 genera of camels flourished throughout North America. (Honey et al 1998)
  • During the Pleistocene, five genera of camels lived in North America. (Dalquest 1992)
  • Hemiauchenia closely related to extinct Camelops. (Webb et al 2006).
  • Hemiauchenia was probably ancestral to other North and South American llamas (Webb et al 2006)
    • South American guanacos, alpacas, vicuñas are among its descendants (Webb 2006)
  • By 10,000 years ago, Hemiauchenia was extinct.

Classification

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: *Artiodactyla (even-toed hoofed animals; includes pigs, sheep goats, cattle, deer)

Family: Camelidae

Genus: Hemiauchenia

Species: Hemiauchenia macrocephala - Extinct Large-headed or Stilt-legged Camel

Describer: Cope, 1893

*Note: New anatomical and DNA evidence on the relationship between Artiodactyla (even-toed ungulates) and Cetacea (whales and dolphins) recently led to a merging of the two orders into a new group, Cetartiodactyla (Montgelard, 1997; reviewed in Kulemzina, 2009). As of October 2012, experts had not agreed on whether to define Cetartiodactyla as an official taxonomic order that would replace Artiodactyla and Cetacea. Some continue to list giraffes in the order Artiodactyla (Franklin, 2011) or use the term Cetartiodactyla without defining it as an order (IUCN, 2008).

Page Citations

Cui et al. (2007)
Dalquest (1991)
Honey et al. (1998)
Janis et al. (2002)
McKenna and Bell (1997)
Scherer (2007)
Webb (1977)
Webb et al. (2006)

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