The Neandertals of northeastern Iberia: new remains from the Cova del Gegant (Sitges, Barcelona).

The present study describes a new juvenile hominin mandible and teeth and a new juvenile humerus from level V of the GP2 gallery of Cova del Gegant (Spain). The mandible (Gegant-5) preserves a portion of the right mandibular corpus from the M1 distally to the socket for the dc mesially, and the age at death is estimated as 4.5-5.0 years. Gegant-5 shows a single mental foramen located under the dm1/dm2 interdental septum, a relatively posterior placement compared with recent hominins of a similar developmental age. The mental foramen in Gegant-5 is also placed within the lower half of the mandibular corpus, as in the previously described late adolescent/adult mandible (Gegant-1) from this same Middle Paleolithic site. The Gegant-5 canine shows pronounced marginal ridges, a distal accessory ridge, and a pronounced distolingual tubercle. The P3 shows a lingually-displaced protoconid cusp tip and a distal accessory ridge. The P4 shows a slightly asymmetrical crown outline, a continuous transverse crest, a mesially placed metaconid cusp tip, a slight distal accessory ridge, and an accessory lingual cusp. The M1 shows a Y5 pattern of cusp contact and a well-developed and deep anterior fovea bounded posteriorly by a continuous midtrigonid crest. Gegant-4 is the distal portion of a left humerus from a juvenile estimated to be between 5 and 7 years old at death. The specimen shows thick cortical bone. Although fragmentary, the constellation of morphological and metric features indicates Neandertal affinities for these specimens. Their spatial proximity at the site and similar ages at death suggest these remains may represent a single individual. The addition of these new specimens brings the total number of Neandertal remains from the Cova del Gegant to five, and this site documents the clearest evidence for Neandertal fossils associated with Middle Paleolithic stone tools in this region of the Iberian Peninsula.

The Neandertal nature of the Atapuerca Sima de los Huesos mandibles.

The recovery of additional mandibular fossils from the Atapuerca Sima de los Huesos (SH) site provides new insights into the evolutionary significance of this sample. In particular, morphological descriptions of the new adult specimens are provided, along with standardized metric data and phylogenetically relevant morphological features for the expanded adult sample. The new and more complete specimens extend the known range of variation in the Atapuerca (SH) mandibles in some metric and morphological details. In other aspects, the addition of new specimens has made it possible to confirm previous observations based on more limited evidence. Pairwise comparisons of individual metric variables revealed the only significant difference between the Atapuerca (SH) hominins and Neandertals was a more vertical symphysis in the latter. Similarly, principal components analysis of size-adjusted variables showed a strong similarity between the Atapuerca (SH) hominins and Neandertals. Morphologically, the Atapuerca (SH) mandibles show nearly the full complement of Neandertal-derived features. Nevertheless, the Neandertals differ from the Atapuerca (SH) mandibles in showing a high frequency of the H/O mandibular foramen, a truncated, thinned and inverted gonial margin, a high placement of the mylohyoid line at the level of the M3, a more vertical symphysis and somewhat more pronounced expression of the chin structures. Size-related morphological variation in the SH hominins includes larger retromolar spaces, more posterior placement of the lateral corpus structures, and stronger markings associated with the muscles of mastication in larger specimens. However, phylogenetically relevant features in the SH sample are fairly stable and do not vary with the overall size of the mandible. Direct comparison of the enlarged mandibular sample from Atapuerca (SH) with the Mauer mandible, the type specimen of H. heidelbergensis, reveals important differences from the SH hominins, and there is no morphological counterpart of Mauer within the SH sample, suggesting the SH fossils should not be assigned to this taxon. The Atapuerca (SH) mandibles show a greater number of derived Neandertal features, particularly those related to midfacial prognathism and in the configuration of the superior ramus, than other European middle Pleistocene specimens. This suggests that more than one evolutionary lineage co-existed in the middle Pleistocene, and, broadly speaking, it appears possible to separate the European middle Pleistocene mandibular remains into two distinct groupings. One group shows a suite of derived Neandertal features and includes specimens from the sites of Atapuerca (SH), Payre, l'Aubesier and Ehringsdorf. The other group includes specimens that generally lack derived Neandertal features and includes the mandibles from the sites of Mauer, Mala Balanica, Montmaurin and (probably) Visogliano. The two published Arago mandibles differ strongly from one another, with Arago 2 probably belonging to this former group, and Neandertal affinities being more difficult to identify in Arago 13. Outside of the SH sample, derived Neandertal features in the mandible only become more common during the second half of the middle Pleistocene. Acceptance of a cladogenetic pattern of evolution during the European middle Pleistocene has the potential to reconcile the predictions of the accretion model and the two phases model for the appearance of Neandertal morphology. The precise taxonomic classification of the SH hominins must contemplate features from the dentition, cranium, mandible and postcranial skeleton, all of which are preserved at the SH site. Nevertheless, the origin of the Neandertal clade may be tied to a speciation event reflected in the appearance of a suite of derived Neandertal features in the face, dentition and mandible, all of which are present in the Atapuerca (SH) hominins. This same suite of features also provides a useful anatomical basis to include other European middle Pleistocene mandibles and crania within the Neandertal clade.