A deciduous maxillary molar: the human specimen from the Middle Pleistocene site of La Polledrara di Cecanibbio (Rome, Italy)

The Middle Pleistocene site of La Polledrara di Cecanibbio (Rome, Central Italy), yielded a large assemblage of fossil mammal remains and artifacts accumulated as a consequence of alternating flooding and swampy phases during MIS 9. In the last decades, the archaeological and paleontological analyses carried out on the site witnessed the presence of human activity in relation to the exploitation of elephant carcasses. Among the fossil remains, a single human deciduous tooth has been found at the site. It is an exfoliated second upper left deciduous molar, heavily worn on the occlusal surface, and preserving some calculus on the cervical margin. The tooth has been lost intra vitam by an individual aged 10-12 years, when compared to modern dental developmental standards. Here we present a detailed morphologic and morphometric description of the tooth through microtomographic high-resolution imaging performed by ATOM (Advanced TOmography and Microscopies) center, CNIS, Sapienza University of Rome. A preliminary taxonomical assessment of the tooth was performed on crown outline morphology. The comparative sample includes Neanderthals, early Homo sapiens (EHS), Upper Palaeolithic (UPHS) and recent (RHS) H. sapiens, and two Homo erectus specimens. Results show that La Polledrara deciduous molar clusters at the margin of the UPHS and RHS groups and outsides the Neanderthal shape variability, thus supporting the hypothesis of a chronospecific attribution to H. heidelbergensis. Further cutting-edge methodologies aimed at reconstructing the early biological life history of this individual, will be applied to fully analyze this exceptional find in the panorama of the Middle Pleistocene in Europe.