''Adianthus'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

litoptern Litopterna (from grc, λῑτή πτέρνα "smooth heel") is an extinct order of fossil hoofed mammals from the Cenozoic era. The order is one of the five great orders of South American ungulates that were endemic to the continent, until th ...

that lived during the Early

Miocene The Miocene ( ) is the first epoch (geology), 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 mea ...

to the Middle Miocene in what is now

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

and

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 ...

Description

This animal is only known from fragmentary remains, mainly from its teeth, and was probably similar to its relative '' Adiantoides''. It was a small animal with generalist teeth, but it had some unusual characteristics. The crown of its teeth was higher than in ''Adiantoides'', and the lower premolars were more molariform. The second lower

incisor Incisors (from Latin ''incidere'', "to cut") are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight (two on each side, top and bottom). Opossums have 18, wher ...

and the lower canine had three lingually directed ridges, forming two closed basins. The first three premolars had two ridges, while the fourth premolar was completely molariform.

Classification

''Adianthus bucatus'' was first described in 1891 by

Florentino Ameghino Florentino Ameghino (born Giovanni Battista Fiorino Giuseppe Ameghino September 19, 1853 – August 6, 1911) was an Argentine naturalist, paleontologist, anthropologist and zoologist, whose fossil discoveries on the Argentine Pampas, especially ...

, based on a single tooth of enigmatic shape, perhaps coming from the so-called "'' Notohippus'' beds". Subsequently, Ameghino described a mandible with teeth as a new species, ''Adianthus patagonicus'' ; however, those remains were later attributed to a different genus, '' Proheptaconus''.Ameghino, F. (1894). ''Enumération synoptique des espèces de mammifères fossiles des formations éocènes de Patagonie''. Imp. de PE Coni é hijos. Chicago In 1991, a new species of ''Adianthus'', ''A. godoyi'', was described by

Richard Cifelli Richard is a male given name. It originates, via Old French, from Old Frankish and is a compound of the words descending from Proto-Germanic ''*rīk-'' 'ruler, leader, king' and ''*hardu-'' 'strong, brave, hardy', and it therefore means 'stron ...

from the Galera Formation of

, preserving a more complete skeleton, including postcranial remains. ''Adianthus'' is the eponymous genus of the

Adianthidae Adianthidae is an extinct family of Litopterna, litopterns that existed from the Middle Eocene (Mustersan) to the Early Miocene (Santacrucian). Description These Arboreal locomotion, scansorial, Viviparity, viviparous animals were actively mobil ...

, a family of small-sized litopterns with a characteristic dentition. ''Adianthus'', despite being little known, seems to have been one of the more specialized members of the family.R. L. Cifelli and M. F. Soria. 1983. Systematics of the Adianthidae (Litopterna, Mammalia). American Museum Novitates 2771:1-25

References

{{Taxonbar, from=Q56328057 Litopterns Miocene mammals of South America Neogene Argentina Fossils of Argentina Fossil taxa described in 1891 Taxa named by Florentino Ameghino Prehistoric placental genera