Adianthidae is an extinct family of

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

that existed from the Middle Eocene (

Mustersan The Mustersan age is a period of geologic time (48.0–42.0 Ma) within the Eocene epoch of the Paleogene, used more specifically within the South American land mammal age (SALMA) classification. It follows the Casamayoran and precedes the Divisader ...

) to the Early Miocene ( Santacrucian).

Description

These scansorial,

viviparous Among animals, viviparity is development of the embryo inside the body of the parent. This is opposed to oviparity which is a reproductive mode in which females lay developing eggs that complete their development and hatch externally from the ...

animals were actively mobile and were

herbivores A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...

. They were small in size when compared to most litopterns. Most species did not exceed the size of a

cat The cat (''Felis catus'') is a domestic species of small carnivorous mammal. It is the only domesticated species in the family Felidae and is commonly referred to as the domestic cat or house cat to distinguish it from the wild members of ...

. Although small in size, the adianthids showed dental features that were already specialized even in the Oligocene genera. The

molars The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone to ...

were equipped with ridges, and the upper molars were provided with crescent-shaped metacones and paracones, with a columnar parastyle and a very reduced or absent mesostyle. The lower fourth

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 mouth ...

was provided with a crested

talonid The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone ...

, and the lower molars were double crescent-shaped or nearly so. The upper fourth premolar was molar-shaped, and the teeth from the third premolar to the upper third molar had three primary dimples and (in the more derived forms) a few accessory dimples behind the prostylar ''cingulum'' in front of the ''cingulum'' of the postipocone.

Naming and reorganization

Adianthidae was named 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 ...

in 1891. It was renamed to Adiantidae by Jaekel in 1911 which is used comparatively less but is synonymous (not disputed). It was reranked to a subfamily Adiantinae by Bordas in 1939. It was assigned to Litopterna (renamed by Jaekel in the same year from Litopterna) by Jaekel in 1911, to

Macraucheniidae Macraucheniidae is a family in the extinct South American ungulate order Litopterna, that resembled various camelids. The reduced nasal bones of their skulls was originally suggested to have housed a small proboscis, similar to that of the sai ...

by Bordas in 1939 and to

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

by Cifelli in 1983 and to Litopterna by Ameghino in 1894 and 1897, by Simpson et al. in 1962, by Cifelli and Soria in 1983, by Bond and Vucetich in 1983 and by Carroll in 1988.

Existence

Temporal range

The first recorded occurrence of Adianthidae was in the

Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

(approx. 48 MYA). The last recorded occurrence of Adianthidae is 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 recen ...

(approx. 16 MYA).

Occurrences

There have been a total of 62 occurrences of Adianthidae, all in

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

especially in present-day

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

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 ...

References

{{Taxonbar, from=Q33134533 Litopterns Prehistoric mammal families Neogene mammals of South America Paleogene mammals of South America Lutetian first appearances Burdigalian extinctions