A morphological intermediate between eosimiiform and simiiform primates from the late middle Eocene of Tunisia: Macroevolutionary and paleobiogeographic implications of early anthropoids

Abstract

Although advanced anthropoid primates (i.e., Simiiformes) are recorded at the end of the Eocene in North Africa (Proteopithecidae, Parapithecidae, and Oligopithecidae), the origin and emergence of this group has so far remained undocumented. The question as to whether these primates are the result of a monophyletic radiation of endemic anthropoids in Africa, or several Asian clades colonizing Africa, is a current focus of paleoprimatology. In this article, we report the discovery of a new anthropoid from Djebel el Kébar in central Tunisia, dating from the late middle Eocene (Bartonian). This taxon, Amamria tunisiensis, new genus and species, currently known by only one isolated upper molar, is among the most ancient anthropoids to be recorded in Africa thus far. Amamria displays a suite of dental features that are primarily observed in Eosimiiformes (stem Anthropoidea). However, it is not allocated to any known family of that group (i.e., Asian Eosimiidae and Afro-Asian Afrotarsiidae) inasmuch as it develops some dental traits that are unknown among eosimiiforms, but can be found in African simiiform anthropoids such as proteopithecids and oligopithecids. With such a mosaic of dental traits, Amamria appears to be a structural intermediate, and as such it could occupy a key position, close to the root of the African simiiforms. Given its antiquity and its apparent pivotal position, the possibility exists that Amamria could have evolved in Africa from Asian eosimiiform or Asian "proto"-simiiform ancestors, which would have entered Africa sometime during the middle Eocene. Amamria could then represent one of the earliest offshoots of the African simiiform radiation. This view would then be rather in favor of the hypothesis of a monophyletic radiation of endemic simiiform anthropoids in Africa. Finally, these new data suggest that there must have been at least two Asian anthropoid colonizers of Africa: the afrotarsiids and the ancestor of Amamria.

A new and primitive species of Protophiomys (Rodentia, Hystricognathi) from the late middle Eocene of Djebel el Kébar, Central Tunisia

“…is therefore the most ancient representative of hystricognathous rodents in Africa that is known thus far. The same is true for the primate recorded at KEB-1 (i.e., Amamria tunisiensis), which represents the most ancient occurrence of anthropoids in Africa (Marivaux et al, 2014).…”

“…1), the sediment consists of glauconitic clays, which were formed locally in lagoonal conditions (see Merzeraud et al, submitted). Radiometric K-Ar analyses performed on few grains of glauconite extracted from the glauconitic clays embedding the fossils, indicate that KEB-1 is late middle Eocene in age (Bartonian; datings ranging from 38.7 ± 1.0 Ma to 40.7 ± 1.1 Ma; see Yans in Marivaux et al, 2014). This new species of Protophiomys from KEB-1 (P. tunisiensis sp.…”

“…Late middle Eocene (Bartonian). Dated at ~39.5 Ma by radiometric K-Ar analyses performed on grains of glauconite extracted from the glauconitic clays embedding the fossils of KEB-1 (see Yans in Marivaux et al, 2014). Etymology.…”

“…However, over the past few decades, fossil discoveries in South Asia have demonstrated that this tropical province was also a major centre of an early hystricognathous rodent radiation (the "baluchimyine" radiation), and most likely the ancestral homeland of the Hystricognathi clade (Hussain et al, 1978;Marivaux et al, 2002Marivaux et al, , 2004 hundred teeth of selacians by wet-screening about three tons of sediment during the course of three field seasons. Among these mammalian teeth, one can be attributed to a primate (Marivaux et al, 2014), another to a hyracoid (unpublished material), and several others (more than fifty) to a rodent. In this paper, we analyze the dental material of that rodent.…”

Hippos stem from the longest sequence of terrestrial cetartiodactyl evolution in Africa

“…3) suggest that the African diversification of the archaic bothriodontines occurred through multiple waves during the latest Eocene and the early Oligocene. Such a complex scenario would not be unique to anthracotheriids, several dispersal events from southeastern Asia to Africa having also been proposed for Eocene primates 43,44 and rodents 45 .…”