List of mandibular morphological features considered in this study.

<p>List of mandibular morphological features considered in this study.</p

Detail of the left side of D2600.

<p>Note the molarized root bifurcation of the left P3.</p

Detail of the spatial relationship between the corpus and ramus in D2600 and D2735.

<p>Note that the ramus is wholly aligned with the corpus in D2600 (left) and displaced backwards, whereas in D2735 (right) the ramus deviates strongly buccalwards (see the text for more details). White bar: 2 cm.</p

Measurement of the angle formed between the internal alveolar border of the corpus and its prolongation in the internal border of the ramus.

<p>This angle measures the spatial relationship between the corpus and ramus. The Atapuerca-SH sample includes the mandibles of individuals I, IV, VI, XII, XIX, XXI, XXII, and XXIII.</p

Summary of the primitive mandibular features in the <i>Homo</i> clade considered in this report.

<p>Traits 1 to 7 are common to D211, D2735 and D2600. However, traits 8 to 14 are derived in D2600.</p

Scheme of the distal part of the <i>corpus</i> of D 2735 and D 2600.

<p>Note how the internal alveolar border, at the level of the mandibular tuberosity, turns buccalwards just behind the M3, as well as the small size of the retromolar area in D2735 (a) in relation to D2600 (b). The different spatial relationship between the corpus and ramus in the two mandibles has an influence on the breadth of the corpus at both the lateral protuberance level and the extramolar sulcus.</p

Anterior view of D2600.

<p>Note the forward position of the anterior marginal tubercles at the level of the canines, the large canine eminences, and the clear mental protuberance.</p

Comparative sample included in this study (originals and high quality casts)*.

<p>No taxonomical attributions are assumed in this table.</p

Projected stratigraphic location of the main hominin remains recovered from Block 2.

<p>Adult individuals composed by D2600 and D4500 (red) and D3900 and D3444 (green) are found in layer B1y. The adolescent individual composed by D2700 and D2735 (red) is recovered from B1x. A third adult individual is found at level B1z (red). Figure combined and modified from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088212#pone-0088212-g001" target="_blank">Figure 1b</a> of Lordkipanidze et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088212#pone.0088212-Lordkipanidze3" target="_blank">[9]</a> and Figure S1–lower- from Lordkipanidze et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088212#pone.0088212-Lordkipanidze4" target="_blank">[11]</a>.</p