Specimens of the study.

<p>Specimens used in the study. * indicates specimens that were not included in the geometrics morphometric analysis due to the state of preservation of the fossils or to their inaccessibility. Bold types indicate when original fossil was examined. Robustness index (RI) of the mandibular corpus are calculated from the thicknesses (Thc) and the heights (Hgt) at the mental foramen level (mf) and at the M2 level. All measurements have been taken in accord with standard procedures defined by <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0059781#pone.0059781-Martin1" target="_blank">[64]</a> and are derived from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0059781#pone.0059781-Condemi2" target="_blank">[36]</a>, with the exception of Zafarraya <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0059781#pone.0059781-BarrosoRuiz1" target="_blank">[39]</a> and the Mezzena mandible (italic, present study).