Table 1.
The studied hominin fossil specimens by species.
Hominin samples and comparative primate samples studied, indicating the number of specimens and teeth analyzed and the final well-preserved dental sample (exhibiting buccal enamel microwear features).
Fig 1.
SEM images of post-mortem damaged teeth that were not included in the buccal microwear analyses.
(a) LP4 OH-65 with patina layers covering the microwear features. (b) LM1 KNM-ER-1171 with perykimata—growth lines—and enamel prisms caused by chemical erosion. (c) RP4 OH-5 with post-mortem physical abrasion caused by rolling over sediments. Scale line is 200 μm.
Fig 2.
Well-preserved buccal microwear surfaces in which buccal striations could be measured.
(a) LP4 OH-69 Homo habilis. (b) RM1 KNM-WT-15000 Homo ergaster. (c) LM1 Peninj Paranthropus boisei. Scale line is 200 μm.
Table 2.
Dental sample showing well-preserved buccal microwear patterns.
Specimens numbers and paleontological information (hominin species, stratigraphic site complex and unit) are provided for all the teeth showing well-preserved buccal microwear patterns.
Table 3.
Average values of the 15 microwear variables analyzed for each taxonomic group considered.
N: Sample Size; the Total Number of Striations (N), Average Length of All Striations (X), and Standard Deviations of the Length (S) are Indicated by Orientation: Horizontal (H), Vertical (V), Mesio-distal (MD), Disto-mesial (DM), and All Striations (T).
Fig 3.
Box plots of microwear total striation density and average striation length by species.
The whiskers show the minimum and maximum values (excluding outliers). The box includes the 25–75 percentiles. Both the median values (lines within the boxes) and means (yellow dots) are shown for the total striation density (NT) and length (XT) by species (sample sizes are indicated in brackets). For the outliers the specimen reference numbers are shown.
Fig 4.
Plot of DF1 on DF2 derived from the Linear Discriminant Analysis of the buccal microwear variables of the hominin groups studied.
Plot of the first two discriminant functions (DF1 x axis, DF2 y axis), derived from the microwear variables (ranked data) for the hominines samples studied (Paranthropus aethiopicus brown, Paranthropus boisei beige, Homo habilis cyan, Homo ergaster red), that explain 93,8% of the total variance (55.9% and 37.9%, respectively). The ellipses show one standard deviation of the sample means (68% confidence interval of the sample). The blue lines represent the loadings of the microwear variables on the discriminant functions. The analysis was made with PAS v. 3.
Fig 5.
Plot of DF1 on DF2 derived from the Linear Discriminant Analysis Analysis of the hominines studied along with all the comparative samples.
Plot of the first two discriminant functions (DF1 x axis, DF2 y axis), derived from the microwear variables (ranked data) for all the specimens studied and the comparative collections, that explain 73,66% of the total variance (57,25% and 16,41%, respectively). The circles represent the 95% confidence intervals of the group centroids assuming equality of covariance matrices (the size of the circle depend on the sample sizes). The red lines indicate the correlations between the variables considered and the two functions shown. The analysis was made with XLSTAT v. 2015.
Fig 6.
Phenetic dendrogram of similarities among group centroids of all the samples considered.
The dissimilarities among groups were measured using Fisher's distance derived from the Linear Discriminant Analysis of all the microwear variables (ranked data) for all groups considered. The diagonal dissimilarity matrix was used to derive a hierarchical cluster analysis using an unweighted average agglomeration method in XLSTAT v. 2015.