Plio‐Pleistocene mammals from Mille‐Logya, Ethiopia, and the post‐Hadar faunal change

Abstract

We describe the non-primate mammalian fauna from the late Pliocene to earliest Pleistocene deposits of Mille-Logya in the Lower Awash Valley, Ethiopia, dated to c. 2.9-2.4 Ma, and divided into three successive units: Gafura, Seraitu, and Uraitele. We identify 41 mammalian taxa (including rodents), the most diverse group being the Bovidae, with 17 taxa. While the Gafura assemblage still resembles those from the earlier Hadar Formation, the younger Seraitu assemblage documents a major turnover. While there is little change in the species present across this interval, the relative abundances of various taxa change dramatically, with suids being largely replaced by opencountry bovids (Alcelaphini and Antilopini). We interpret this faunal change as reflective of an environmental shift, contemporaneous with the replacement of Australopithecus afarensis by Homo in the area.

Early Pleistocene large mammals from Maka’amitalu, Hadar, lower Awash Valley, Ethiopia

“…However, the mesiodistal compression of the Maka’amitalu dentitions is obvious and comparable to that the Matabaietu sample of K. phillipi , whereas K. limnetes tends to have longer and more complex third molars than K. phillipi . In our view, the Mille-Logya specimens attributed to Kolpochoerus by Geraads et al (2021) likely represent early forms of Metridiochoerus . For example, the M3 with specimen number MLP-2655 ( Geraads et al, 2021 : Fig.…”

“…In our view, the Mille-Logya specimens attributed to Kolpochoerus by Geraads et al (2021) likely represent early forms of Metridiochoerus . For example, the M3 with specimen number MLP-2655 ( Geraads et al, 2021 : Fig. 3Q ) displays a relatively high crown, main cusps with relatively flat sides, and accessory cusps that are relatively tall and columnar.…”

“…A.L. 656-1 is narrower than the handful of m3s known for early M. andrewsi , such as those from Ledi-Geraru and Mille-Logya ( Lazagabaster et al, 2018 ; Geraads et al, 2021 ) and is considerably shorter than those of derived M. andrewsi , M. hopwoodi , and M. compactus from <2 Ma deposits at Koobi Fora and elsewhere ( Harris & White, 1979 ).…”

“…The only other diagnostic character for this species may be in the molars, which possess mesiodistally compressed lateral pillars compared to K. afarensis or K. limnetes , but not as extreme as those of derived K. majus specimens. From Mille-Logya, Geraads et al (2021) listed Early Pleistocene kolpochoere material as Kolpochoerus sp., suggesting that isolated teeth of K. phillipi cannot be easily distinguished from those of K. limnetes . However, the mesiodistal compression of the Maka’amitalu dentitions is obvious and comparable to that the Matabaietu sample of K. phillipi , whereas K. limnetes tends to have longer and more complex third molars than K. phillipi .…”

“…Faunas of Early Pleistocene age have been reported from Gona ( Everett, 2010 ; Semaw et al, 2020 ) and the Middle Awash ( Kalb et al, 1982 ; de Heinzelin et al, 1999 ), but no comprehensive account of these assemblages has yet been published. Geraads et al (2021) recently provided a summary of the Mille-Logya fossil mammals, including the Early Pleistocene (~2.5–2.4 Ma) Uraitele exposures, but some taxa remain undescribed ( e.g ., Cercopithecidae).…”