medial pterygoid tubercle is large. Unlike most Neanderthals, there is no retromolar space (a large gap between the last molar and the end of the body of the mandible). The upper incisors are shovel-shaped (the lingual, or tongue, side is distinctly concave), a feature characteristic of other Eurasian human populations, including modern. The canines bear the cingulum (a protuberance toward the base) and the essential ridge (toward the midline) like more derived species, but retain the cuspules (small bumps) near the tip and bordering incisor like more archaic species. The upper premolar crowns are rather derived, being nearly symmetrical and bearing a lingual cusp (on the tongue side), and a cingulum and longitudinal grooves on the cheekward side. The upper molars feature several traits typically seen in Neanderthals. The mandibular teeth, on the other hand, are quite archaic. The P3 (the first lower premolar) has a strongly asymmetrical crown and complex tooth root system. P3 is smaller than P4 like in more derived species, but like other early Homo, M1 (the first lower molar) is smaller than M2 and the cusps of the molar crowns make a Y shape. The distribution of enamel is Neanderthal-like, with thicker layers at the periphery than at the cusps. Based on two canine teeth (ATD6- 69 and ATD6-13), the thickness of the enamel and the proportion of the tooth covered by the gums vary to the same degree as for males and females of modern humans and many other apes, so this may be due to sexual dimorphism, with females having smaller teeth, relatively thicker enamel, and smaller proportion of gum coverage. The parietal bones (each being one side of the back part of the top of the skull) are flattened, and conjoin at a peak at the midline. This "tent-like" profile is also exhibited in more archaic African H. ergaster and Asian H. erectus. Like H. ergaster, the temporal styloid process just below the ear is fused to the base of the skull. The brow ridges are prominent. The upper margin of the squamous part of temporal bones (on the side of the skull) is convex, like in more derived species. The brain volume of ATD6-15, perhaps belonging to an 11-year-old, may have been or more based on frontal bone measurements. For comparison, present-day modern humans average 1,270cm3 for males and 1,130cm3 for females, with a standard deviation of roughly 115 and 100cm3.