''Hemiauchenia''Paleobiology Database - ''Hemiauchenia'' basic info
/ref> is a genus of laminoid camelids that evolved in

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the C ...

in the

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent ...

period about 10 million years ago. This genus diversified and moved to South America in the

Early Pleistocene The Early Pleistocene is an unofficial sub-epoch in the international geologic timescale in chronostratigraphy, being the earliest division of the Pleistocene Epoch within the ongoing Quaternary Period. It is currently estimated to span the time ...

, as part of the

Great American Biotic Interchange The Great American Biotic Interchange (commonly abbreviated as GABI), also known as the Great American Interchange and the Great American Faunal Interchange, was an important late Cenozoic paleozoogeographic biotic interchange event in which la ...

, giving rise to modern lamines. The genus became extinct at the end of the Pleistocene.

Broad features of genus ''Hemiauchenia''

The genus name is derived from the grc, ἡμι- (, "half"-) and αὐχήν (, "neck"). Species are specified using

Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...

adjectives or Latinised names from other languages.

North American fossils

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

Mexico Mexico ( Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Gua ...

. ''H. minima'' has been found in Florida, and ''H. guanajuatensis'' in Mexico.

South American fossils

Fossils of ''Hemiauchenia'' in South America are restricted to the

Pleistocene The Pleistocene ( , often referred to as the '' Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed i ...

and have been found in the Luján and Agua Blanca Formations of

Buenos Aires Province Buenos Aires (), officially the Buenos Aires Province (''Provincia de Buenos Aires'' ), is the largest and most populous Argentine province. It takes its name from the city of Buenos Aires, the capital of the country, which used to be part of t ...

and

Córdoba Province, Argentina Córdoba () is a province of Argentina, located in the center of the country. Its neighboring provinces are (clockwise from the north) Santiago del Estero, Santa Fe, Buenos Aires, La Pampa, San Luis, La Rioja, and Catamarca. Together with ...

, the Tarija Formation of

Bolivia , image_flag = Bandera de Bolivia (Estado).svg , flag_alt = Horizontal tricolor (red, yellow, and green from top to bottom) with the coat of arms of Bolivia in the center , flag_alt2 = 7 × 7 square p ...

, Pilauco of Osorno, Los Lagos,

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...

and

Paraíba Paraíba ( Tupi: ''pa'ra a'íba''; ) is a state of Brazil. It is located in the Brazilian Northeast, and it is bordered by Rio Grande do Norte to the north, Ceará to the west, Pernambuco to the south and the Atlantic Ocean to the east. Paraíba ...

Ceará Ceará (, pronounced locally as or ) is one of the 26 states of Brazil, located in the northeastern part of the country, on the Atlantic coast. It is the eighth-largest Brazilian State by population and the 17th by area. It is also one of the ...

, and the Touro Passo Formation of

Rio Grande do Sul Rio Grande do Sul (, , ; "Great River of the South") is a state in the southern region of Brazil. It is the fifth-most-populous state and the ninth largest by area. Located in the southernmost part of the country, Rio Grande do Sul is border ...

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

.''Hemiauchenia''
at

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.org

Distinguishing characteristics of members of ''Hemiauchenia''

''H. vera'' ( "true ''hemiauchenia''")

* Relatively low-crowned teeth (part of visible teeth ends close to gums) * Large caniniform (canine-like) upper first

premolar The premolars, also called premolar teeth, or bicuspids, are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant in the permanent set of teeth, making eight premolars total in the mou ...

* Retention of lower third

''H. blancoensis'' ("Blancan ''hemiauchenia''")

* Named for Blancan Age

stratum In geology and related fields, a stratum ( : strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as e ...

where typically found * Shorter mandibular

diastema A diastema (plural diastemata, from Greek διάστημα, space) is a space or gap between two teeth. Many species of mammals have diastemata as a normal feature, most commonly between the incisors and molars. More colloquially, the condition ...

(teeth-spacing between incisors and molars) than ''H. macrocephala'' and ''H. vera'' * Caniniform upper first

* Absent second

* Upper third

present or absent * Lower crowned molars

''H. macrocephala'' ("great-headed ''hemiauchenia''")

* Possesses a larger skull relative to other species * Long, robust limbs * Large skeletal size * Presence of a

deciduous In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, aft ...

upper second

* Fully molariform deciduous second

(its infant bicuspids were like molars) * High- crowned molars * Thick layer of

cementum Cementum is a specialized calcified substance covering the root of a tooth. The cementum is the part of the periodontium that attaches the teeth to the alveolar bone by anchoring the periodontal ligament.Illustrated Dental Embryology, Histology, ...

on the teeth * Broad

mandibular symphysis In human anatomy, the facial skeleton of the skull the external surface of the mandible is marked in the median line by a faint ridge, indicating the mandibular symphysis (Latin: ''symphysis menti'') or line of junction where the two lateral halves ...

(line where the bones of the jaw join together) with incisors in a vertical fashion

''H. minima'' ("least ''hemiauchenia''")

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

Other species

Also, a few lesser known species, such as ''H. paradoxa'', ''H. seymourensis'', ''H. edensis'' and ''H. guanajuatensis'', have been found. According to which source is consulted, these may or may not be considered legitimate taxa.

Classification history

Prior to 1974, fossil specimens now thought to be ''Hemiauchenia'' were classified as '' Holomeniscus'', ''

Lama Lama (; "chief") is a title for a teacher of the Dharma in Tibetan Buddhism. The name is similar to the Sanskrit term '' guru'', meaning "heavy one", endowed with qualities the student will eventually embody. The Tibetan word "lama" means "hi ...

'', and '' Tanupolama'', until S. David Webb proposed that these North and South American fossil species were part of a single genus. This has been accepted by all subsequent researchers, although in 2013, Carolina Saldanha Scherer questioned the inclusion of a certain North American species and suggested that ''Hemiauchenia'' is

paraphyletic In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and most of its descendants, excluding a few monophyletic subgroups. The group is said to be paraphyletic ''with respect to'' the excluded subgroups. In ...