HEIDELBERG JAW

also called Mauer Jaw, enigmatic human mandible, thought to be nearly 400,000 years old, found in 1907 in the great sand pit at Mauer, southeast of Heidelberg, Ger. Elephant and rhinoceros remains found in association indicate a warm climate; the jaw has been assigned to an early interstadial of the middle Pleistocene. The chinless mandible is massive and apelike, with ascending branches almost as broad as they are high. The teeth, proportionately too small for so large a jaw, are human. The dental arch is parabolic without spaces between the canines and first premolars, and the molars are like those of modern man, but larger. The fossil, long an isolated discovery, is difficult to classify. It was originally designated Homo heidelbergensis and later judged to be a European example of Homo erectus, but its taxonomic position remains uncertain. The Montmaurin mandible (France) and Ternifine fossils (Algeria)-both sometimes considered examples of Homo erectus-are the most similar to the Heidelberg jaw of other known fossils.