title: Limpet Shells from the Aterian Level 8 of El Harhoura 2 Cave (Témara, Morocco): Preservation State of Crossed-Foliated Layers.
abstract: The exploitation of mollusks by the first anatomically modern humans is a central question for archaeologists. This paper focuses on level 8 (dated around ∼ 100 ka BP) of El Harhoura 2 Cave, located along the coastline in the Rabat-Témara region (Morocco). The large quantity of Patella sp. shells found in this level highlights questions regarding their origin and preservation. This study presents an estimation of the preservation status of these shells. We focus here on the diagenetic evolution of both the microstructural patterns and organic components of crossed-foliated shell layers, in order to assess the viability of further investigations based on shell layer minor elements, isotopic or biochemical compositions. The results show that the shells seem to be well conserved, with microstructural patterns preserved down to sub-micrometric scales, and that some organic components are still present in situ. But faint taphonomic degradations affecting both mineral and organic components are nonetheless evidenced, such as the disappearance of organic envelopes surrounding crossed-foliated lamellae, combined with a partial recrystallization of the lamellae. Our results provide a solid case-study of the early stages of the diagenetic evolution of crossed-foliated shell layers. Moreover, they highlight the fact that extreme caution must be taken before using fossil shells for palaeoenvironmental or geochronological reconstructions. Without thorough investigation, the alteration patterns illustrated here would easily have gone unnoticed. However, these degradations are liable to bias any proxy based on the elemental, isotopic or biochemical composition of the shells. This study also provides significant data concerning human subsistence behavior: the presence of notches and the good preservation state of limpet shells (no dissolution/recrystallization, no bioerosion and no abrasion/fragmentation aspects) would attest that limpets were gathered alive with tools by Middle Palaeolithic (Aterian) populations in North Africa for consumption.
authors.affiliation: Université Paris Sud, CNRS UMR GEOPS 8148, bâtiment 504, campus universitaire, 91405 Orsay cedex, France.
authors.forename: Julius
authors.initials: J
authors.lastname: Nouet
authors.affiliation: CEA, CNRS IRAMIS, UMR SIS2M 3299, LIONS, CEA-Saclay, F- 91191 Gif-sur-Yvette, France.
authors.forename: Corinne
authors.initials: C
authors.lastname: Chevallard
authors.affiliation: ISTO, CNRS UMR 7327, 1A rue de la Férolerie 45071 Orléans cedex 2, France.
authors.forename: Bastien
authors.initials: B
authors.lastname: Farre
authors.affiliation: Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany.
authors.forename: Gernot
authors.initials: G
authors.lastname: Nehrke
authors.affiliation: Université Toulouse Jean Jaurès, CNRS UMR TRACES 5608, Maison de la Recherche, 5 allée Antonio Machado, 31058 Toulouse, France.
authors.forename: Emilie
authors.initials: E
authors.lastname: Campmas
authors.affiliation: Muséum National d'Histoire Naturelle, Département de Préhistoire, CNRS UMR 7194, Musée de l'Homme, bureau 345, Paris, France.
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Stoetzel
authors.affiliation: Institut National des Sciences de l'Archéologie et du Patrimoine, angle rues 5 et 7 Rabat Instituts, Madinat Al Irfane, Rabat Hay Riyad, Morocco.
authors.forename: Mohamed Abdeljalil
authors.initials: MA
authors.lastname: El Hajraoui
authors.affiliation: Muséum National d'Histoire Naturelle, Département de Préhistoire, CNRS UMR 7194, Musée de l'Homme, bureau 345, Paris, France.
authors.forename: Roland
authors.initials: R
authors.lastname: Nespoulet
mesh_terms: D060105:Animal Shells / Q000033:anatomy & histology / Q000737:chemistry*; D000818:Animals; D005075:Biological Evolution; D059552:Caves; D005580:Fossils; D049851:Gastropoda / Q000033:anatomy & histology*; D009018:Morocco; D010163:Paleontology; D011309:Preservation, Biological / Q000706:statistics & numerical data*