A total of 25 hominin specimens, mostly isolated teeth, have been recovered from three BRT localities (BRT-VP-1, BRT-VP-2 and BRT-VP-3) thus far. Fourteen of these specimens, including the holotype and paratypes of A. deyiremeda, were reported in Haile-Selassie et al.2. Continued fieldwork since 2015 resulted in the discovery of additional, mostly dentognathic specimens (Table 1). A brief description of these specimens is provided in the Supplementary Information (also see Extended Data Figs. 1 and 2). One of the newly recovered specimens is a juvenile mandible, BRT-VP-2/135 (Fig. 2), which most likely eroded out from the same stratigraphic horizon as the BRT foot (BRT-VP-2/73; Fig. 1d). It was recovered approximately 300 m northeast of BRT-VP-2/73, and the difference in developmental age and distance between the two specimens shows that they did not belong to the same individual.
Fig. 2: The BRT-VP-2/135 mandible and its dentition. a, Micro-CT scan rendering showing the occlusal view of the mandible. Tooth crowns are shown in white and preserved roots in yellow. b, Left lateral view of the mandible. c, Left lateral view of the mandible with crowns, roots and unerupted permanent dentition visible. d, Right lateral view of the mandible. e, Right lateral view of the mandible with crowns, roots and unerupted permanent dentition visible. Occlusal and labial or buccal views of permanent dentition are shown. f, Left I 1 . g, Left I 2 . h, Left P 3 (mesial view included). i, Left P 4 . j, Left M 1 . k, Right M 1 . l, Right P 4 . m, Right P 3 (mesial view included). n, Right canine. o, Right I 2 . p, Right I 1 . Full size image
Table 1 Newly recovered Pliocene hominins from BRT, Woranso-Mille, Ethiopia Full size table
BRT-VP-2/135 consists of most of the corpus and a near-complete deciduous dentition, with the deciduous incisors (di 1–2 ) having already been exfoliated. The mandible also retains a total of 12 permanent teeth: the right and left incisors (I 1 and I 2 ; both erupting); the right canine still in the crypt and isolated mesial half of the left canine; the right and left third and fourth premolars (P 3 and P 4 ) still in the crypt; and the right and left first molars (M 1 s). Both M 1 s show slight wear facets on the protoconid and hypoconid, indicating that they were in occlusion with the maxillary teeth even though their root apices are still open. This mixed dentition allows an evaluation of the pattern of dental development as well as an estimate of the age of death of BRT-VP-2/135. When compared with other infant-to-juvenile hominin mandibular specimens at the same M 1 developmental state (the root three-quarters complete), the developmental status of BRT-VP-2/135 is similar to other early australopiths, specifically LH 3 (A. afarensis) and KNM-KP 34725 (A. anamensis), both of which evince a great ape-like pattern of relatively delayed incisor formation22 (Extended Data Fig. 3 and Supplementary Table 1). An age at death estimate for BRT-VP-2/135 matches a chimpanzee-equivalent age of 4.47 years (range of 3.48–5.46 years), which is similar to age at death estimates for geologically younger hominins from South Africa including DNH 107 (4.82 years; Paranthropus robustus), Sts 24 (4.35 years; Australopithecus africanus) and StW 151 (4.65 years; early Homo) and to the geologically older KNM-KP 34725 (3.94 years; A. anamensis) from eastern Africa23. Details are provided in Supplementary Information.
The base of the BRT-VP-2/135 corpus and cortical bone in the symphyseal region are both missing. The lateral face of the corpus on the left side, however, is well preserved, showing the absence of the lateral corpus hollow (Fig. 2b), which is present in and diagnostic of both juvenile and adult mandibles of A. afarensis24. BRT-VP-2/258, a left edentulous mandible recovered during the 2025 field season, is about the same ontogenetic age and size of BRT-VP-2/135 and it also lacks the lateral corpus hollow (Extended Data Fig. 2l–m). BRT-VP-2/135, as does BRT-VP-2/258, lacks a deciduous canine (d c )–deciduous first molar (dm 1 ) jugum (equivalent of C 1 –P 3 jugum in adults) which is characteristic of A. afarensis14,15. A. africanus juvenile mandibles such as Taung also lack these features. A single mental foramen is positioned low on the corpus at the level of the distal dm 2 , slightly posterior than in most A. afarensis juveniles where it is positioned at dm 1 or dm 1 –dm 2 . BRT-VP-2/258 is similar to the A. afarensis condition in this regard where the mental foramen is positioned mid-corpus at the mesial dm 2 level. The ascending ramus rises at the posterior M 1 level. The symphysis is damaged, although the preserved part shows that it is more posteriorly receding than in A. afarensis juveniles of comparable age.
Deciduous teeth
The left d c , distal half of the left dm 1 crown and both dm 2 s of BRT-VP-2/135 are preserved. The occlusal crown outline of the d c is oval, comparable with the deciduous canines of A. afarensis and A. anamensis25,26. The heavily damaged dm 1 crown obscures any taxonomically informative morphology. The left dm 2 is preserved intact, whereas the enamel surfaces on the hypoconid, metaconid and mesial face of the right dm 2 are missing. The protoconid, hypoconid and hypoconulid of dm 2 all have variably sized dentine pits on their cusp tips. Morphologically, the occlusal outline of both dm 2 s is broadly similar to those of A. afarensis and A. anamensis (there are no dm 2 s reported for A. ramidus). The dm 2 s of BRT-VP-2/135 are, however, mesiodistally shorter and much smaller in crown area, falling outside the known range of A. afarensis27 and A. africanus28, but within the known range of A. anamensis29 (Fig. 3a and Supplementary Table 2).
Fig. 3: Quantitative comparison of the lower dentition in early hominins. a–f, Box-and-whisker plots of crown area of the dm 2 (a), C 1 (b), P 3 (c), C 1 :P 3 ratio (d), P 4 (e) and M 1 (f) in A. ramidus, A. anamensis, A. afarensis and A. africanus compared with A. deyiremeda. The box in each plot represents the first to third quartiles of the dimensions, the line inside the box shows the median, and the horizontal lines outside the box represent the maximum and minimum values. The sample size is indicated by n. A statistical summary of the dental metrics used for this figure is provided in Supplementary Table 2 and Supplementary Data 2. The data were compiled from refs. 18,30 (A. ramidus), refs. 26,29 (A. anamensis), refs. 10,20,21,27 (A. afarensis) and ref. 28 (A. africanus). Full size image
Incisors
The central incisors of BRT-VP-2/135 are emerging and close to the level of the occlusal plane, whereas the lateral incisors are only slightly beyond alveolar emergence. The incisor crowns are absolutely larger than those of A. ramidus (n = 4)18,30 but fall within the known range of A. anamensis26,29 and A. afarensis10,27.
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