''Aztlanolagus'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

rabbit Rabbits are small mammals in the family Leporidae (which also includes the hares), which is in the order Lagomorpha (which also includes pikas). They are familiar throughout the world as a small herbivore, a prey animal, a domesticated ...

that lived during the

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of the twelve periods of the ...

in what is now the Southern to Southwestern

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

and northern

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

. ''Aztlanolagus agilis'' is currently the only recognized species, though differences among recovered fossils suggest that there may have been other species. The generic name refers to

Aztlán Aztlán (from or romanized ''Aztlán'', ) is the ancestral home of the Aztec peoples. The word "Aztec" was derived from the Nahuatl a''ztecah'', meaning "people from Aztlán." Aztlán is mentioned in several ethnohistorical sources dating from t ...

, the legendary place of origin of the

Nahua peoples The Nahuas ( ) are a Uto-Nahuan ethnicity and one of the Indigenous people of Mexico, with Nahua minorities also in El Salvador, Guatemala, Honduras, Nicaragua, and Costa Rica. They comprise the largest Indigenous group in Mexico, as well as ...

as recorded in the mythological accounts of the

Aztec The Aztecs ( ) were a Mesoamerican civilization that flourished in central Mexico in the Post-Classic stage, post-classic period from 1300 to 1521. The Aztec people included different Indigenous peoples of Mexico, ethnic groups of central ...

s and other Nahua groups. By some traditions, this legendary locale is placed in the border regions of the

Southwestern United States The Southwestern United States, also known as the American Southwest or simply the Southwest, is a geographic and cultural list of regions of the United States, region of the United States that includes Arizona and New Mexico, along with adjacen ...

and adjacent northern

. Fossils range in age from the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

(

Blancan The Blancan North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 4,750,000 to 1,806,000 years BP, a period of .Rancholabrean The Rancholabrean North American Land Mammal Age on the geologic timescale is a North American faunal stage in the North American Land Mammal Ages chronology (NALMA),Sanders, A.E., R.E. Weems, and L.B. Albright III (2009) Formalization of the mid- ...

North American land mammal ages). The known distribution is from southeastern

Arizona Arizona is a U.S. state, state in the Southwestern United States, Southwestern region of the United States, sharing the Four Corners region of the western United States with Colorado, New Mexico, and Utah. It also borders Nevada to the nort ...

( Madrean Sky Islands region), to central

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

and from central

Colorado Colorado is a U.S. state, state in the Western United States. It is one of the Mountain states, sharing the Four Corners region with Arizona, New Mexico, and Utah. It is also bordered by Wyoming to the north, Nebraska to the northeast, Kansas ...

to southern Chihuahua.

''Aztlanolagus'' may be distinguished from all other known leporids as follows. Lower incisor terminates under diastema and well anterior to P₃. Three reentrant folds present on trigonid of P₃: an anterior reentrant fold, an anterointernal reentrant fold (rarely cut off to form an enamel lake), and an anteroexternal fold. At all growth stages, a posteroexternal reentrant fold extends approximately halfway across occlusal surface of P₃ to a narrow enamel lake lying next to lingual border; enamel lake rarely joined to external reentrant to form the ''Lepus''-type pattern (Hibbard, 1963). On P₄ to M₂, external fold extends to enamel of lingual wall. Anterior border of talonid on P₄-M₂ deeply convoluted, often with alternating series of major and minor enamel loops.... (Russell and Harris 1986:632-633)

The

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

of ''Aztlanolagus agilis'' was deposited at the

University of Texas at El Paso The University of Texas at El Paso (UTEP) is a public university, public research university in El Paso, Texas, United States. Founded in 1913 as the State School of Mines and Metallurgy, it is the third oldest academic component of the Univers ...

br>Biodiversity Collections
(Specimen No
UTEP:ES:1-1202
. The specimen, collected b
Richard A. Smartt
is a left

dentary In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone ...

with

premolar The premolars, also called premolar Tooth (human), teeth, or bicuspids, are transitional teeth located between the Canine tooth, canine and Molar (tooth), molar teeth. In humans, there are two premolars per dental terminology#Quadrant, quadrant in ...

s 3 and 4 and molars 1 and 2. The youngest records of the genus date to around 30,000 years ago. ''Aztlantolagus'' has been recognised as most closely related to the extinct genus ''Pliopentalagus'' (from which it probably descended) and the living Japanese Amami rabbit (''Pentalagus''), with a 2024 study suggesting that ''Aztlantolagus'' should be synonymised with ''Pliopentalagus''.

References

* Russell, Brett D., and Arthur H. Harris. 1986. A New Leporine (Lagomorpha: Leporidae) from Wisconsinan Deposits of the Chihuahuan Desert. Journal of Mammalogy 67(4):632-639, . * Winkler, A. J., and Y. Tomida. 1988. New records of the small leporid ''Aztlanolagus agilis'' Russell and Harris, Leporidae: Leporinae. Southwestern Naturalist 33:391-396. {{Taxonbar, from=Q16999880, from2=Q4832996 Pliocene mammals of North America Pleistocene mammals of North America Prehistoric lagomorphs Cenozoic mammals of North America Fossil taxa described in 1986 Chihuahuan Desert Fauna of the Rio Grande valleys Natural history of the Mexican Plateau Prehistoric placental genera Rabbits