DOI: 10.5061/dryad.vq83bk42m
title: Postcanine dental metrics for hominin fossils from the Omo, Ethiopia, and the comparative dataset

description: These are data that were analyzed for the taxonomic assignments for the
 3.75 Ma to 1.09 Ma hominin postcanine teeth from the Usno Formation and
 the Shungura Formation, Lower Omo Valley, Ethiopia. The dataset includes
 the linear dimensions, the morphological scores, and the 2-dimensional
 occlusal areas of the postcanine teeth from the Omo. We also include the
 linear dimensions (mesiodistal and buccolingual dimensions) for the
 comparative sample (hominin fossils that provide important taxonomic
 context) that were primarily culled from the literature.
description: For the Omo hominin sample: The maximum
 mesiodistal (MD) lengths and maximum buccolingual (BL) breadths for the
 Omo teeth were measured by L. Hlusko using Mitutoyo calipers from the
 original fossils at the Ethiopian Heritage Authority in Addis Ababa. For
 molars, we report and analyze the BL breadth across the mesial cusps. Each
 measurement was collected three times, the average used as the data point.
 If a portion of a crown was broken or heavily worn, compromising our
 ability to determine the actual dimension of the crown, we did not record
 that measurement. For the MD dimensions, many of the crowns have
 interstitial wear. Our MD dimensions report the actual length of the crown
 as it currently is; we did not attempt to correct for the wear. We
 excluded measurements from overly-worn (&gt;1mm) Omo teeth.
 Cusp area data were collected by Ian Towle from the photographs
 of the original specimens taken by Franck Guy. When photographed, each
 molar was oriented so that the occlusal crown area was maximized (e.g.,
 Grine <em>et al.</em> 2009). The orientation that best
 captured the occlusal view horizontal to the camera lens was used for
 measuring cusp areas. The occlusal images of complete molars were analyzed
 using ImageJ software (Schindelin <em>et al.</em> 2015).
 Individual images were uploaded into ImageJ and calibrated using the set
 scale function by measuring the millimeters scale bar in each image.
 Outlines were drawn separately around each cusp following Brophy
 <em>et al.</em> (2021) and Bailey <em>et al.</em>
 (2004). Similar methodology has been employed in a variety of samples
 (e.g., Martín-Albaladejo <em>et al.</em> 2017; Quam
 <em>et al.</em> 2009; Suwa <em>et al.</em> 1994).
 The occlusal areas of the ‘main’ cusps were calculated (paracone,
 protocone, metacone, and hypocone for the upper molars, and the
 protoconid, metaconid, hypoconid, entoconid and hypoconulid for the lower
 molars; see Fig. 3). All cusp areas were then summed to obtain a total
 crown area (following Bailey <em>et al.</em> 2004; Wood
 <em>et al.</em> 1983). If required, corrections of the cusp
 outlines were made to account for loss of tissue, especially in
 interproximal regions. This reconstruction was performed in ImageJ
 following Bailey (2004). If accessory cusps were present, they were
 divided equally between the adjacent ‘main’ cusps following Wood
 <em>et al.</em> (1983). Each cusp was measured to the nearest
 1 mm<sup>2</sup>, following Kondo and Townsend (2006).
 Individual cusp areas were defined by following the main fissures of the
 occlusal surface. Crowns in which occlusal fissures were completely
 removed through wear were not recorded, following Grine <em>et
 al.</em> (2009). However, if substantial areas of the main fissures
 were eroded by wear but the course of each could be estimated, we
 extrapolated the course based on the preserved part of the fissures
 (following Gómez‐Robles <em>et al.</em> 2011). Relative cusp
 areas were calculated by dividing the absolute area of each cusp by the
 total crown area. Morphological scores were collected
 following the methodology outlined in Martinón-Torres <em>et
 al.</em> (2012), in which a subset of ASUDAS traits (including some
 altered trait categories) are recorded for each specimen, with other
 ASUDAS traits from Turner <em>et al.</em> (1991) added for
 particular features/teeth. For this study, we recorded 37 traits that are
 described in Table 5 of the corresponding manuscript/publication.
 Specimens were scored twice by the same author (Marina Martínez de
 Pinillos), first using the high-resolution casts and then from photographs
 of the original specimens. We only included teeth in the morphological
 analysis if they had all traits scored. For the
 Comparative Sample: The comparative dataset of
 mesiodistal and buccolingual dimensions of hominin postcanine teeth was
 culled from the published literature by Leslea Hlusko with assistance from
 Mario Modesto-Mata, Ian Towle, Marina Martínez de Pinillos, and Arthur
 Thiebaut. These comparative data consist of measurements taken by T.D.
 White, L.J. Hlusko, and culled from the following citations (Tobias
 & Koenigswald 1964; Tobias 1967; Jacob 1973; White 1977, 1980;
 Johanson <em>et al.</em> 1982; Wood & Van Noten 1986;
 Leakey & Walker 1988; Kyauka & Ndessokia 1990; Tobias
 1991; Wood 1991; Schrenk et al. 1993; Walker & Leakey 1993; Kimbel
 et al. 1994; Brunet et al. 1995; Gabunia & Vekua 1995; Kimbel et
 al. 1997; Suwa et al. 1997; Asfaw et al. 1999; Kullmer 1999; White et al.
 2000; Brown et al. 2001; Ward et al. 2001; Blumenschine et al., 2003; Prat
 et al. 2003; Kimbel et al 2004; Kaifu et al. 2005; Semaw et al. 2005;
 White et al. 2006; Kaifu et al. 2007; Spoor et al. 2007; Martinón-Torres
 et al. 2008; Haile-Selassie & WoldeGabriel 2009; Haile-Selassie et
 al. 2010; Harrison 2011; Zaim et al. 2011; Clarke 2012; Leakey et al.
 2012; Domínguez-Rodrigo et al. 2013; Ward et al. 2013; Zanolli et al.
 2014; Haile-Selassie & Melillo 2015; Haile-Selassie et al. 2015;
 Simpson et al. 2015; White et al. 2015; Haile-Selassie et al. 2016; Xing
 et al. 2016; Grine et al. 2019; Noerwidi 2020; Skinner et al. 2020;
 Melillo et al. 2021; Xing et al. 2021; Villmoare et al. 2025.
 In total, 367 specimens are included, representing 820 teeth.
 This datasheet includes the reference to the published article from which
 we culled the data. Each specimen is listed by specimen number and
 includes the taxonomic assignment given to it in the cited publication. We
 also include the taxonomic label that we used for this specimen in our
 analysis for the Omo fossils, as well as the tooth position. In our
 analyses, we keep <em>Australopithecus deyiremeda</em>
 separate in the species-level analyses. However, given the high degree of
 overlap in size and shape with <em>Au. afarensis</em> and the
 small number of individuals attributed to other Late Pliocene species, we
 use a taxonomic category that we call
 “<em>Australopithecus</em> Late Pliocene”
 (<em>Australopithecus</em> LP, or <em>Au</em>. LP)
 that includes <em>Australopithecus afarensis</em>,
 <em>Au. bahrelghazali</em>, and <em>Kenyanthropus
 platyops</em>. We also combine all of the fossils from eastern
 Africa that have been identified to early <em>Homo</em>, such
 as <em>H. habilis</em> and <em>H.
 rudolfensis,</em> into one category called
 “<em>Homo</em> early eastern Africa”
 (<em>Homo</em> EEA). For this comparative sample, when the
 source from which we culled the measurements included an estimation of the
 mesiodistal length that corrected for interproximal wear, we used this
 reconstructed length estimate. Our aim is to capture the biological
 potential and variation observed within each taxon. In contrast, our
 measurements of the Omo fossils record the actual mesiodistal length as we
 did not attempt to correct for interstitial wear. Consequently, our
 mesiodistal dimensions are, by and large, within a millimeter of the
 actual crown mesiodistal length. The reader is cautioned to place a buffer
 around the edges of the observed variation for both the comparative and
 our Omo mesiodistal measurements. We did not include
 P<sub>3</sub> mesiodistal or buccolingual dimensions for the
 two species of <em>Ardipithecus</em> nor for <em>Au.
 anamensis</em> in our comparative analyses. The morphology of these
 early hominin P<sub>3</sub>s is distinct from the later, more
 derived hominins (Suwa <em>et al</em>. 2009 SOM).
 Consequently, the mesiodistal and buccolingual dimensions are not directly
 comparable. Therefore, <em>Ardipithecus</em> is not included
 in analyses of P<sub>3</sub> linear metrics. Additionally, the
 genus-level analyses of P<sub>3</sub> metrics for
 <em>Australopithecus</em> do not include <em>Au.
 anamensis</em>. The exclusion of the linear measurements that
 capture this ancestral morphology is further justified in that none of the
 Omo specimens demonstrate this geologically older morphology.
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description: # Postcanine dental metrics for hominin fossils from the Omo, Ethiopia,
 and the comparative dataset
 [https://doi.org/10.5061/dryad.vq83bk42m](https://doi.org/10.5061/dryad.vq83bk42m) There are two datasets provided here. Both are uploaded as tab-delimited txt files. The first contains all of the data collected from the Omo hominin postcanine teeth analyzed in the study presented in the pre-print on PaleorXiv ([https://doi.org/10.31233/osf.io/g7kfx](https://doi.org/10.31233/osf.io/g7kfx)): mesiodistal and buccolingual linear dimensions, morphological scores, and 2-dimensional occlusal cusp areas. The second dataset contains mesiodistal and buccolingual linear dimensions for 820 teeth that were culled from the published literature for 367 comparative specimens.  ## Description of the data and file structure ## FILE: Hlusko_etal_Omo_data.txt **Columns:** **Specimen number** = the unique specimen number associated with each fossil **Stratigraphy** = the geological stratigraphic horizon within the Shungura or Shungura-equivalent (for the specimens from the Usno Formation) Formation member.  **Tooth_ID** = indicates the tooth position. The options are P3 UPPER for a maxillary third premolar, P4 UPPER for maxillary fourth premolar, M1 UPPER for maxillary first molar, M2 UPPER for maxillary second molar, M3 UPPER for maxillary third molar, P3 LOWER for mandibular third premolar, P4 LOWER for mandibular fourth premolar, M1 LOWER for mandibular first molar, M2 LOWER for mandibular second molar, and M3 LOWER for mandibular third molar **Jaw =** This indicates whether the tooth is maxillary or mandibular. **Tooth** = This is another abbreviation for the tooth position. The options are P3, P4, M1, M2, and M3, that are abbreviations for the third premolar, fourth premolar, first molar, second molar, and third molar. **MD** = mesiodistal dimension of the crown in millimeters **BL** = buccolingual dimension of the crown in millimeters **MDxBL** = the 2-dimensionsal occlusal area of the crown estimated as the MD dimensions multiplied by the BL dimension **MD/BL** = the ratio of the mesiodistal dimension of the crown divided by the BL dimension. This ratio provides a way to quantify how rectangular or square the tooth is when viewed from occlusal **included in LDA** = the specimen was included in our Linear Discriminant Analysis **included in morph scoring** = the specimen was included in our morphological scoring analysis **included in cusp area study** = the specimen was included in our cusp area study **The next 20 columns** report the 2-dimensional molar cusp areas measured in two different ways: "all cusps" or "4-cusps". For the 4-cusps method, ancillary cusps were split between the two adjacent ´main´ cusps. In this case, the hypoconulid would be split equally between the hypoconid and entoconid, for example. Measurements are in mm^2^. | Variable | Description | | :----------------------------------------- | :------------------------------------------------------------------------------------------------------------------ | | All Cusps Method Protoconid Area | mm^2^ occlusal-view area of the protoconid of the mandibular molar | | All Cusps Method Metaconid Area | mm^2^ occlusal-view area of the metaconid of the mandibular molar | | All Cusps Method Hypoconid Area | mm^2^ occlusal-view area of the hypoconid of the mandibular molar | | All Cusps Method Entoconid Area | mm^2^ occlusal-view area of the entoconid of the mandibular molar | | All Cusps Method Hypoconulid Area | mm^2^ occlusal-view area of the hypoconulid of the mandibular molar | | All Cusps Method Cusp 6 (Entoconulid) Area | mm^2^ occlusal-view area of the entoconulid of the mandibular molar | | All Cusps Method Cusp 7 (Metaconulid) Area | mm^2^ occlusal-view area of the metaconulid of the mandibular molar | | 4 Cusps Method Protoconid Area | mm^2^ occlusal-view area of the protoconid of the mandibular molar | | 4 Cusps Method Metaconid Area | mm^2^ occlusal-view area of the metaconid of the mandibular molar and, if present, half the area of C7 | | 4 Cusps Method Hypoconid Area | mm^2^ occlusal-view area of the hypoconid of the mandibular molar and, if present, half the area of the hypoconulid | | 4 Cusps Method Entoconid Area | mm^2^ occlusal-view area of the entoconid of the mandibular molar and, if present, half the area of C7 | | All Cusps Method Paracone Area | mm^2^ occlusal-view area of the paracone of the maxillary molar | | All Cusps Method Protocone Area | mm^2^ occlusal-view area of the protocone of the maxillary molar | | All Cusps Method Metacone Area | mm^2^ occlusal-view area of the metacone of the maxillary molar | | All Cusps Method Hypocone Area | mm^2^ occlusal-view area of the hypocone of the maxillary molar | | All Cusps Method Metaconule Area | mm^2^ occlusal-view area of the metaconule of the maxillary molar | | 4 Cusps Method Paracone Area | mm^2^ occlusal-view area of the paracone of the maxillary molar | | 4 Cusps Method Protocone Area | mm^2^ occlusal-view area of the protocone of the maxillary molar | | 4 Cusps Method Metacone Area | mm^2^ occlusal-view area of the metacone and, if present, half of the metaconule | | 4 Cusps Method Hypocone Area | mm^2^ occlusal-view area of the hypocone and, if present, half of the metaconule | **The next 33 columns** provide the morphological scores for the traits included in this study:  | **Maxillary and mandibular premolars** | | | :------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Distal accessory ridge | ridge development between the cusp tip and the distolingual marginal ridge in the buccal cusp  | | Mesial accessory ridge  | ridge development between the cusp tip and the mesiolingual marginal ridge in the buccal cusp | | Transverse crest   | expression of a transverse crest connecting the main cusps of the premolars | | Distobuccal cusplet | presence of a secondary buccal cusp detached from the main buccal cusp | | **Maxillary premolars** | | | Distosagittal ridge | ridge from the apex of the buccal cusp to the distal occlusal border at or near the sagittal sulcus of the maxillary premolars | | Mesial and distal accessory cusps | small accessory cusps at the mesial and/or distal ends of the sagittal grooves on maxillary premolars | | Tricusped premolars | additional distolingual cusp of the maxillary premolars | | Buccal essential crest or ridge | degree of expression and possible bifurcation of the maxillary premolars | | Lingual essential crest or ridge | same scoring as the buccal essential crest of the maxillary premolars | | **Mandibular premolars** | | | Lingual cusp variation | refers to the number of lingual cusps, including main and accessory lingual cusps. frequently, accessory cusps adopt the shape of tubercles without a clear tip and are difficult to differentiate from enamel wrinkles | | Mesiolingual groove | groove on the mesiolingual aspect of the tooth | | Metaconid placement | position of the metaconid relative to the protoconid | | Crown asymmetry | shape of the lingual contour of the tooth in occlusal view | | **Maxillary Molars** | | | :------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Cusp 3 (Metacone) | refers to the expression of this cusp | | Cusp 4 (Hypocone | refers to the expression of this cusp | | Cusp 5 (Metaconule) | presence of a secondary distal cusp in addition to cusp 5 | | Crista obliqua | expression of an enamel crest connecting the protocone and the metacone | | Transverse crest | crest connecting the mesial aspect of the protocone and the paracone | | Carabelli’s trait | tubercle of various degrees of expression on the lingual surface of the protocone | | Parastyle | tubercle of various degrees of expression on the buccal surface of the paracone | | Mesial marginal accessory  tubercles   | presence of tubercles in the mesial marginal ridge of upper molars | | Distal fovea | development of a triangular depression mesial to the distal marginal ridge | | **Mandibular Molars** | | | Anterior fovea | fovea or groove on the anterior occlusal surface, distal to the mesial marginal ridge | | Middle trigonid crest | crest connecting the mesial aspects of the protoconid and the metaconid | | Distal trigonid crest | crest connecting the distal aspect of the protoconid and the metaconid | | Deflecting wrinkle | the essential crest of the paraconid is distally deflected | | C5 (Hypoconulid) | refers to the size of the hypoconulid or the cusp 5 | | C6 (Entoconulid) | the presence of a hypoconulid is not necessarily required to record a C6. When there is one single distal cusp and it occupies a lingual position, we consider it a C6 | | Double C6 | presence of a secondary distal cusp between cusps 5 and 6 | | C7 (Metaconulid) | accessory cusp between the metaconid and the entoconid | | Groove pattern | type of groove pattern | | Protostylid | tubercle of various degrees of expression on the buccal surface of the lower molars | | Mesial marginal ridge | development of the mesial marginal ridge | ## **FILE: Hlusko_etal_comparative_data.txt** This sheet contains the mesiodistal and buccolingual dimensions collected from the published literature.  Columns: **Taxon** = the genus and species to which the specimen was assigned in the cited publication (or is commonly referred to today) **Genus** = the genus assigned to the specimen in the cited publication **Species category** = the species-level category that Hlusko et al. used in their analysis. We combined some of the species, such as *H. habilis* and *H. rudolfensis* were combined into the *Homo* early eastern African (*Homo* EEA) category for our analyses.  **Specimen** = the specimen number of the fossil **Tooth** = refers to tooth position: P3 is for the third premolar, P4 is the fourth premolar, M1 is the first molar, M2 is the second molar, M3 is the third molar **Jaw** = indicates if the tooth is maxillary or mandibular **Side** = indicates R for right or L for left side, when known **MD** = mesiodistal dimension of the crown in millimeters **BL** = buccolingual dimension of the crown in millimeters **MDxBL** = the 2-dimensionsal occlusal area of the crown estimated as the MD dimensions multiplied by the BL dimension **MD/BL** = the ratio of the mesiodistal dimension of the crown divided by the BL dimension. This ratio provides a way to quantify how rectangular or square the tooth is when viewed from occlusal **Data from** = the citation from which the dimensions were pulled **Additional info** = provides information on where in the publication we found the measurements, if this is not straight-forward to discern ## Sharing/Access information The comparative data were published in the following sources: | Publications from which comparative data were culled by Leslea Hlusko, with assistance from Mario Modesto-Mata, Marina Martínez de Pinillos, Ian Towle, and Arthur Thiebaut: | | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Asfaw, B. et al. *Australopithecus garhi*: A New Species of Early Hominid from Ethiopia. Science 284, 629–635 (1999). | | Blumenschine, R. J. et al. Late Pliocene Homo and Hominid Land Use from Western Olduvai Gorge, Tanzania. Science 299, 1217–1221 (2003). | | Brown, B., Brown, F. H. & Walker, A. New hominids from the Lake Turkana basin, Kenya. J Hum Evol 41, 29–44 (2001). | | Brunet, M. et al. The first australopithecine 2,500 kilometres west of the Rift Valley (Chad). Nature 378, 273–275 (1995). | | Clarke, R. J. A Homo habilis maxilla and other newly-discovered hominid fossils from Olduvai Gorge, Tanzania. Journal of Human Evolution 63, 418–428 (2012). | | Domínguez-Rodrigo, M. et al. First Partial Skeleton of a 1.34-Million-Year-Old Paranthropus boisei from Bed II, Olduvai Gorge, Tanzania. PLOS ONE 8, e80347 (2013). | | Gabunia, L. & Vekua, A. A Plio-Pleistocene hominid from Dmanisi, East Georgia, Caucasus. Nature 373, 509–512 (1995). | | Grine, F. E. et al. Complete permanent mandibular dentition of early Homo from the upper Burgi Member of the Koobi Fora Formation, Ileret, Kenya. J Hum Evol 131, 152–175 (2019). | | Haile-Selassie, Y. & Melillo, S. M. Middle Pliocene hominin mandibular fourth premolars from Woranso-Mille (Central Afar, Ethiopia). J Hum Evol 78, 44–59 (2015). | | Haile-Selassie, Y. & WoldeGabriel, G. Ardipithecus Kadabba: Late Miocene Evidence from the Middle Awash, Ethiopia. (University of California Press, 2009). | | Haile-Selassie, Y. et al. Dentognathic remains of Australopithecus afarensis from Nefuraytu (Woranso-Mille, Ethiopia): Comparative description, geology, and paleoecological context. J Hum Evol 100, 35–53 (2016). | | Haile-Selassie, Y. et al. New species from Ethiopia further expands Middle Pliocene hominin diversity. Nature 521, 483–488 (2015). | | Haile‐Selassie, Y., Saylor, B. Z., Deino, A., Alene, M. & Latimer, B. M. New hominid fossils from Woranso‐Mille (Central Afar, Ethiopia) and taxonomy of early Australopithecus. Am J Phys Anthropol 141, 406–417 (2010). | | Harrison, T. Hominins from the Upper Laetolil and Upper Ndolanya Beds, Laetoli. in Paleontology and Geology of Laetoli: Human Evolution in Context (ed. Harrison, T.) 141–188 (Springer Netherlands, Dordrecht, 2011).  | | Jacob, T. Palaeoanthropological discoveries in Indonesia with special reference to the finds of the last two decades. J Hum Evol 2, 473–485 (1973). | | Johanson, D. C., White, T. D. & Coppens, Y. Dental remains from the Hadar formation, Ethiopia: 1974–1977 collections. Am J Phys Anthropol 57, 545–603 (1982). | | Kaifu, Y. et al. A new Homo erectus molar from Sangiran. J Hum Evol 52, 222–226 (2007). | | Kaifu, Y., Aziz, F. & Baba, H. Hominid Mandibular Remains from Sangiran: 1952–1986 Collection. Am J Phys Anthropol 128, 497–519 (2005). | | Kimbel, W. H., Johanson, D. C. & Rak, Y. Systematic assessment of a maxilla of Homo from Hadar, Ethiopia. Am J Phys Anthropol 103, 235–262 (1997). | | Kimbel, W. H., Johanson, D. C. & Rak, Y. The first skull and other new discoveries of Australopithecus afarensis at Hadar, Ethiopia. Nature 368, 449–451 (1994). | | Kimbel, W. H., Rak, Y., Johanson, D. C., Holloway, R. L. & Yuan, M. S. The Skull of Australopithecus Afarensis. (Oxford University Press, 2004).  | | Kullmer, O., Sandrock, O., Abel, R., Bromage, G. & Juwayeyi, Y. M. News and Views: The first Paranthropus from the Malawi Rift. J Hum Evol 37, 121–127 (1999). | | Kyauka, P. S. & Ndessokia, P. A new hominid tooth from Laetoli, Tanzania. J Hum Evol 19, 747–750 (1990). | | L.J. Hlusko  | | Leakey, M. G. et al. New fossils from Koobi Fora in northern Kenya confirm taxonomic diversity in early Homo. Nature 488, 201–204 (2012). | | Leakey, R. E. & Walker, A. New Australopithecus boisei specimens from east and west Lake Turkana, Kenya. Am J Phys Anthropol 76, 1–24 (1988). (For tooth ID as a P4 see: Suwa, G. The premolar of KNM-WT 17000 and relative anterior to posterior dental size. J Hum Evol 18, 795–799 (1989).) | | Martinón-Torres, M. et al. Dental remains from Dmanisi (Republic of Georgia): morphological analysis and comparative study. J Hum Evol 55, 249–273 (2008). | | Melillo, S. M. et al. New Pliocene hominin remains from the Leado Dido’a area of Woranso-Mille, Ethiopia. J Hum Evol 153, 102956 (2021). | | Noerwidi, S. (2020). Hominin diversity in the western Indonesian archipelago during the Quaternary: A dental record perspective (Phdthesis, Museum national d’histoire naturelle - MNHN PARIS ; Universitat Rovira i Virgili (Tarragone, Espagne)). Museum national d’histoire naturelle - MNHN PARIS ; Universitat Rovira i Virgili (Tarragone, Espagne). Retrieved from [https://theses.hal.science/tel-03680512 ](https://theses.hal.science/tel-03680512 ) | | Prat, S., Brugal, J.-P., Roche, H. & Texier, P.-J. Nouvelles découvertes de dents d’hominidés dans le membre Kaitio de la formation de Nachukui (1,65–1,9 Ma), Ouest du lac Turkana (Kenya). C R Palevol 2, 685–693 (2003). | | Schrenk, F., Bromage, T. G., Betzler, C. G., Ring, U. & Juwayeyi, Y. M. Oldest Homo and Pliocene biogeography of the Malawi rift. Nature 365, 833–836 (1993). | | Semaw, S. et al. Early Pliocene hominids from Gona, Ethiopia. Nature 433, 301–305 (2005). | | Simpson, S. W. et al. Late Miocene hominin teeth from the Gona Paleoanthropological Research Project area, Afar, Ethiopia. J Hum Evol 81, 68–82 (2015). | | Skinner, M. M., Leakey, M. G., Leakey, L. N., Manthi, F. K. & Spoor, F. Hominin dental remains from the Pliocene localities at Lomekwi, Kenya (1982–2009). J Hum Evol 145, 102820 (2020). | | Spoor, F. et al. Implications of new early Homo fossils from Ileret, east of Lake Turkana, Kenya. Nature 448, 688–691 (2007). (Supplemental) | | Suwa, G. et al. Early pleistocene Homo erectus fossils from konso, southern Ethiopia. Anthropol Sci 115, 133–151 (2007). | | Suwa, G. et al. The first skull of Australopithecus boisei. Nature 389, 489–492 (1997). | | T.D White | | Tobias, P. V. & Koenigswald, G. von. A comparison between the Olduvai hominines and those of Java and some implications for hominid phylogeny. Nature 204, 515–518 (1964). | | Tobias, P. V. Olduvai Gorge, Volume 2: The Cranium of Australopithecus (Zinjanthropus) boisei. vol. 2 (Cambridge University Press, Cambridge, 1967). | | Tobias, P.V., 1991. Olduvai Gorge. Volume 4: Parts I-IV. The skulls endocasts and teeth of Homo habilis. Cambridge University Press. | | Villmoare, B., Delezene, L.K., Rector, A.L. *et al.* New discoveries of *Australopithecus* and *Homo* from Ledi-Geraru, Ethiopia. *Nature* (2025). [https://doi.org/10.1038/s41586-025-09390-4](https://doi.org/10.1038/s41586-025-09390-4) | | Walker A, Leakey REF. The Nariokotome Homo erectus Skeleton. (Harvard University Press, Cambridge, MA, 1993). | | Ward, C. V., Leakey, M. G. & Walker, A. Morphology of Australopithecus anamensis from Kanapoi and Allia bay, Kenya. Journal of human evolution 41, 255–368 (2001). | | Ward, C. V., Manthi, F. K. & Plavcan, J. M. New fossils of Australopithecus anamensis from Kanapoi, West Turkana, Kenya (2003–2008). Journal of human evolution 65, 501–524 (2013). | | White, T. D. Additional fossil Hominids from Laetoli, Tanzania: 1976–1979 specimens. Am J Phys Anthropol 53, 487–504 (1980). | | White, T. D. et al. Asa Issie, Aramis and the origin of Australopithecus. Nature 440, 883–889 (2006). | | White, T. D. New fossil hominids from Laetolil, Tanzania. Am J Phys Anthropol 46, 197–229 (1977). | | White, T. D., Lovejoy, C. O., Asfaw, B., Carlson, J. P. & Suwa, G. Neither chimpanzee nor human, Ardipithecus reveals the surprising ancestry of both. Proc Natl Acad Sci USA 112, 4877–4884 (2015). | | White, T. D., Suwa, G., Simpson, S. & Asfaw, B. Jaws and teeth of Australopithecus afarensis from Maka, Middle Awash, Ethiopia. Am J Phys Anthropol 111, 45–68 (2000). | | Wood, B. A. & Van Noten, F. L. Preliminary observations on the BK 8518 mandible from Baringo, Kenya. Am J Phys Anthropol 69, 117–127 (1986). | | Wood, B. A. Koobi Fora Research Project. Volume 4, Hominid Cranial Remains. (Clarendon Press, Oxford (England), 1991). | | Xing, S. et al. Early Pleistocene hominin teeth from Meipu, southern China. J Hum Evol 151, 102924 (2021). | | Xing, S. et al. Hominin teeth from the Middle Pleistocene site of Yiyuan, eastern China. J Hum Evol 95, 33–54 (2016). | | Zaim, Y. et al. New 1.5 million-year-old Homo erectus maxilla from Sangiran (Central Java, Indonesia). J Hum Evol 61, 363–376 (2011). | | Zanolli, C. et al. The late early pleistocene human dental remains from Uadi Aalad and Mulhuli-Amo (Buia), Eritrean Danakil: macromorphology and microstructure. J Hum Evol 74, 96–113 (2014). | ## Code/Software The R script for our analyses can be found here: [https://github.com/ljhlusko/Omo](https://github.com/ljhlusko/Omo) ([https://doi.org/10.5281/zenodo.17198867](https://doi.org/10.5281/zenodo.17198867))