Adianthidae is an extinct family of
litopterns that existed from the Middle Eocene (
Mustersan) to the Early Miocene (
Santacrucian
The Santacrucian age is a period of geologic time (17.5 – 16.3 Ma) within the Early Miocene epoch of the Neogene, used more specifically with SALMA classification in South America. It follows the Colhuehuapian and precedes the Friasian age.
...
).
Description
These
scansorial
Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. The habitats pose num ...
,
viviparous animals were actively mobile and were
herbivores. They were small in size when compared to most litopterns. Most species did not exceed the size of a
cat. Although small in size, the adianthids showed dental features that were already specialized even in the
Oligocene
The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...
genera. The
molars 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, 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 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
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 the G ...
(renamed by Jaekel in the same year from Litopterna) by Jaekel in 1911, to
Macraucheniidae by Bordas in 1939 and to
Macrauchenioidea by Cifelli in 1983 and to
Litopterna
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 the G ...
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 (approx. 48 MYA). The last recorded occurrence of Adianthidae is in the
Miocene (approx. 16 MYA).
Occurrences
There have been a total of 62 occurrences of Adianthidae, all in
South America especially in present-day
Argentina 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