Anancus

''Anancus'' is an extinct genus of "tetralophodont gomphothere" native to Afro-Eurasia, that lived from the Tortonian stage of the late Miocene until its extinction during the Early Pleistocene, roughly from 8.5–2 million years ago.

Taxonomy

''Anancus'' was named by Auguste Aymard in 1855. It is traditionally allocated to Gomphotheriidae, often as the only member of the subfamily Anancinae. Recently, some authors have excluded ''Anancus'' along with other tetralophodont gomphotheres from Gomphotheriidae, and regarded them as members of Elephantoidea instead.

Description

Two largely complete individuals of ''Anancus arvernensis'' reached shoulder heights of around , with a volumetric estimate suggesting a body mass of around , comparable to living African bush elephants. The tusks were largely straight and lacked enamel (though enamel was present in juvenilesTheodorou, G., Spjeldnaes, N., Hanken, N. M., Lauritzen, S. E., Velitzelos, E., Athanassiou, A., et al. (2000). Description and taphonomic investigations of Neogene Proboscidea from Rhodos, Greece. ''Annales Géologiques des Pays Helléniques, 38'', 133–156.) and were slender, and proportionally large, with a large tusk of the species ''Anancus avernensis'' from Stoina, Romania measuring in length with an estimated mass of . The tusks varied from projecting forward parallel to each other, to being outwardly divergent from each other, depending on the species. The skull is proportionally tall and short, with an elevated dome and an enlarged tympanic bulla. Unlike more primitive gomphotheres, the mandible was brevirostrine (shortened), and lacked lower tusks. The skull of ''Anancus'' species is very similar to living elephants and like them they probably had free-hanging (pendulous) trunks. The molars were typically tetralophodont (bearing four crests or ridges) but were pentalophodont in some species. The premolars were absent in all species other than ''A''. ''kenyensis''. On the upper molars, the posterior pretrite central conules were reduced, as were the anterior pretrite central conules on the lower molars. The pretrite and posttrite half-loph(id)s were dislocated from each other, resulting in the successive loph(id)s exhibiting an alternating pattern.

Diet

Dietary preferences of ''Anancus'' varied between species. Dental microwear analysis of ''Anancus arvernensis'' specimens from the Early Pleistocene of Europe generally suggests that it was a browser, consuming twigs, bark, seeds and fruit, with a browsing diet also proposed for the Early Pliocene South African ''A.'' ''capensis''. The East African late Miocene-early Pliocene ''A. kenyensis'' and Pliocene ''A. ultimus'' have individuals with varying browsing, grazing, and mixed feeding (both browsing and grazing) diets, with a grazing diet proposed for ''Anancus'' specimens from the Pliocene of India based on isotopic analysis. ''Anancus osiris'' from the Pliocene of North Africa is suggested to have been a mixed feeder with a large grass intake based on microwear.

Evolution

''Anancus'' is suggested to have evolved from ''Tetralophodon'' or a ''Tetralophodon''-like ancestor. The oldest known species of ''Anancus'' is ''A. perimensis'', with fossils known from the Tortonian ~ 8.5 million years ago Siwalik Hills of Pakistan. ''Anancus'' entered Europe approximately 7.2 million years ago and around 7 million years ago dispersed into Africa. ''Anancus'' first appeared in China around 6 million years ago (''A. sinensis''). ''Anancus'' disappeared from Asia and Africa around the end of the Pliocene

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