This mandible was found by a workman in the Rösch sandpit just north of the village of Mauer near Heidelberg, Germany, in 1907. The workman showed the find to the anatomist O. Schoentensack, who provided the initial description of the specimen. The mandible is complete with only the premolars and first two molars on the left side missing. The molars were recovered separately, although the premolars were lost.

The mandible itself is large, and robustly built like that seen in Homo erectus, with broad ascending rami. The corpus of the mandible is deep and thicker than a modern human's. The lack of a projecting chin is another morphological difference from modern humans. Schoentensack proposed the species name Homo heidelbergensis for the Mauer specimen. This assignment has been problematic over the years. The robust morphology of the jaw shows affinities to Homo erectus populations from the same time period, yet the tooth morphology is decidedly more "modern" in appearance. Most researchers agree that the Mauer mandible is not Homo erectus. For a long time many scientists placed the mandible a rather confusing taxon: "Archaic" Homo sapiens. Recently, members of this taxon have been separated at the species level and given a separate species name: Homo heidelbergensis.