The Aramis Member (Sagantole formation) includes the Gàala Tuff Complex-Daam Aatu Basaltic Tuff interval which has produced a taxonomically diverse vertebrate assemblage including the primitive hominid
During the last decades, new canid material from the African Mio-Pliocene has increased our knowledge of the evolutionary history of this family. The idea that the first record of canids from eastern Africa was around 4–4.5 Ma was widely accepted until recently
The published indications regarding the Lukeino Formation and Lemudong’o Late Miocene Kenyan sites considerably deepen the initial immigration of
The Ethiopian rift system comprises the Afar Depression, the Main Ethiopian Rift, and a wide rifted zone located in the Southwest of the country. The Central Awash Complex is a domelike horst located in the southwestern Afar rift and includes the Sagantole Formation with alluvial and volcanic sediments, tephras and basaltic lavas exposed. One of the Sagantole Members, Aramis, includes a thin stratigraphic interval between the Gàala Tuff Complex and the Daam Aatu Basaltic Tuff (GATC-DABT). This effectively isochronous, largely terrestrial unit has produced a taxonomically extensive vertebrate assemblage including the primitive hominid
The base of the Aramis Member is defined by the Gàala (camel) Tuff Complex (MA92-12), a 0.5–2-m thick, crystal-vitric tuff. The GATC variably overlies conglomerates and/or brown to orange silty clays of the underlying Haradaso Member. The Daam Aatu (baboon) Basaltic Tuff (MA92-38B) crops out a few centimetres to ∼5 m above the GATC. The DABT ranges in thickness from a few centimetres to ∼1 m. It is a poorly consolidated tuff composed chiefly of bedded and laminated dark grey basaltic glass lapilli and scoria in its lower third (∼15–20 cm). This tuff was deposited subaerially on a remarkably flat landscape and was not reworked. WoldeGabriel et al.
The carnivore assemblage within the GATC-DABT interval comprises at least 14 species, Canidae (one species), Felidae (five species), Viverridae (one species), Herpestidae (at least three species), Hyaenidae (two species), Ursidae (one species), Mustelidae (one species). The canid remains are described below as
Class
Order
Infraorder
Family
Subfamily
Genus
Measurements (in millimetres). Holotype (ARA VP6/21): greatest length of m1 = 13.6; greatest breadth of m1 = 6; greatest length of m2 = 7.8; greatest breadth of m2 = 5.4; greatest length of molars (m1–m2) = 21.4.
Maxillary fragment (KUS-VP-1/197) with P4–M2; right mandible fragment with M1–M2 (ARA-VP-6/21); right m2 (KUS-VP-2/73); left m2 (KUS-VP-2/198); left C0 (ARA-VP-1/2112); left (talon) of M1 (ARA-VP-1/137). On the basis of the locality where the remains were found and additional dental criteria, a minimum number of three adult individuals was calculated; one each from Aramis VP-1, -6 and Kuseralee VP-2.
The morphology and size of the dentition is mostly comparable to the samples attributed to the genus
KUS-VP-1/197 is a left maxillary fragment that preserves the posterior portion of a third premolar, a broken carnassial with missing protocone and damaged blade, a well preserved upper first and second molar (partially worn), and a broken alveolous of an M3 (
The M1 of KUS-VP-1/197 is robust, with larger dimensions than the small
The Lukeino (BAR 212’01) and Lemudong’o (KNM-NK 41284) M1s present an almost identical pattern, for what the original attribution
The M1 of KUS-VP-1/197 (
The M2 of KUS-VP-1/197 (
No M2s have been recorded from Lukeino or Lemudong’o, and this molar is also absent from the published material from Langebaanweg. Its morphology remains unknown for
The Aramis specimen differs from
ARA-VP-6/21 is a right mandible fragment with m1–m2, and the mesial part of the alveolus of an m3 (
The m1 of ARA-VP-6/21 has a salient protoconid with the usual steep, sub-vertical distal slope to the talonid. There is a distinct but low buccal cingulum at the base of the protoconid. The buccal side of the protoconid expands, showing a well-rounded profile that differs from
The m2 of ARA-VP-6/21 is also scarcely worn, and presents a strong labial cingulum, a double entoconid, and a high protoconid (
Two more m2s have been recovered from the Aramis Member: KUS-VP-2/198 is a left m2 and KUS-VP-2/73 is a right m2. Both specimens present a considerable wear stage and show a similar morphological pattern that could include them within the same individual. The pattern observed in these two molars is identical to the one on place (ARA-VP-6/21). Second lower molars are not represented in any of the sites with
The M1 of
The
Morphological differences are even clearer in the lower carnassial, when comparing the Aramis fossil and
The remains from Aramis represent, up to date, the most abundant
The Middle Awash Project involves a number of individuals who conducted the Middle Awash fieldwork, who must be especially thanked for their participation on survey and excavations. The Authority for Research and Conservation of Cultural Heritage provided permits to fieldwork and access to the collections in the Paleoanthropology Laboratory of the National Museum of Ethiopia. Alemu Ademassu is thanked for assistance and management during the study of the collections at the National Museum of Ethiopia. The Middle Awash paleoanthropological research project is funded by the U.S. National Science Foundation (NSF) (BCS-9910344). F.C. Howell guided me to study the Middle Awash carnivore collections during my postdoctoral stay in the Human Evolution Research Centre, and supported me in all senses: comments, advice, and open access to his outstanding library. I have received an excellent assistance and care during all my stays at the University of California, Berkeley, at the Museum of Vertebrate Zoology and at the Museum of Paleontology, which provided me with helpful casts of
I am indebted to Berhane Asfaw and Tim White who gave me the additional opportunity to study the Middle Awash carnivore material. Jorge Morales was extremely supportive, providing very valuable advice and discussion on the analysis, with comments and fossil material for comparison that helped to clarify the arguments exposed in this study. I also thank my colleagues Mark Goodwin, Leslea Hlusko, and Henry Gilbert, from UC Berkeley, and Yohannes Haile-Selassie, for assistance and discussions. I thank also the project Revealing Homind Origin Initiative (RHOI) of the NSF for funding the workshop at Poitiers.
Buccal (a), lingual (b) and occlusal (c): ARA-VP-6/21 right mandible fragment with m1–m2 of
Fig. 1. Vues buccale (a), linguale (b) et occlusale (c) : ARA-VP-6/21, fragment de la mandibule droite avec m1–m2 de
KUS-VP2/73 (right m2): labial (a), lingual (b); KUS-VP2/198 (left m2): labial (c), lingual (d); (e): KUS-VP2/73; (f): KUS-VP2/198 (both occlusal). Scale bar 1 cm.
Fig. 2. KUS-VP2/73, (m2 droite) : vues labiale (a), linguale (b) ; KUS-VP2/198 (m2 gauche) : vues labiale (c), linguale (d) ; (e) : KUS-VP2/73; (f) : KUS-VP2/198 (toutes deux en vue occlusale). Barre d’échelle 1 cm.
Occlusal (a) and buccal (b): KUS-VP-1/197 left maxillary fragment of
Fig. 3. Vues occlusale (a) et buccale (b) : KUS-VP-1/197 : fragment de maxillaire gauche de
Plot of length/breadth relationship of upper M1 of
Fig. 4. Relations longueur–largeur de la M1 supérieure de l’espèce
Comparison of upper dental dimensions in
Tableau 1 Comparaison entre les dimensions des dents supérieures