APPROCHE TAPHONOMIQUE EN CÉMENTOCHRONOLOGIE : réexamen du niveau 4 du Pech-de-l'Azé I (Carsac, Dordogne, France) - HAL-SHS - Sciences de l'Homme et de la Société Accéder directement au contenu
Article Dans Une Revue PALEO : Revue d'Archéologie Préhistorique Année : 2009

APPROCHE TAPHONOMIQUE EN CÉMENTOCHRONOLOGIE : réexamen du niveau 4 du Pech-de-l'Azé I (Carsac, Dordogne, France)

Résumé

Introduction This paper propose the application of A. J. Stutz method of diagenetic cementum modification identification to the skeletochronological analysis of Level 4 of the Pech-de-l'Azé I study previously published by some of us (Armand et al., 2001). Skeletochronology is based on the observation of seasonal cementum deposits and has long been used in zooarchaeology to access the season of death of human preys (Saxon and Higham, 1968; Spiess, 1979 ; Burke, 1995; Martin, 1994; Pike-Tay et al., 1999). Cementum is a bonelike tissue that allows the connection between tooth roots and the gingival, through the periodontal ligament, (Lieberman and Meadow, 1992 ; Klevezal', 1996; Dieckwisch, 2001). It apposes itself along mammal tooth roots from their formation, until the death of the animal. In most mammal populations, this growth follows predictable seasonal cycles which exhibit the succession of a fast growth deposit (also called "Zone") from mid-spring to autumn and a slow growth one (Annulus and/or LAG) in winter (Klevezal' and Kleinenberg, 1969 ; Martin, 1994; Burke and Castanet, 1995; Klevezal', 1996 ; Moffit, 1998 ; Peck, 2004). Seasonal patterns of cementum depositions produce microscopically distinct incremental levels, which may exhibit one or more of a variety of ultrastructural, microstructural, and histological patterns (Figure 1). Taphonomy and cementum Although lots of researchers have underlined the existence of post-mortem modification of the tooth tissues (Figure 2), few of them specifically focalised on the taphonomic modifications that can alter the seasonal record such as weathering (Figure 2). One of the most important of these taphonomic processes is the apatite crystal re-crystallisation that can mimic biogenic deposit that cannot be identified with the classical methods used (Stutz, 2002a, 2002b). However, in polarizing microscopy (Gilbert, 1989), the use of the Lambda plate can help to resolve this issue by colouring the taphonomic and the biogenic deposit in two different ways (figure 3). Figure 4 proposes an example of the lambda plate application for the identification of diagenesis modifications. We present the application of this method to the skeletochronological study of Pech-de-l'Azé I level 4 originally conducted by some of us (Armand et al, 2001). Our objectives was firstly to propose a revaluation of the previous seasonal results and, secondly, to present an example of the impact of that kind of modifications on archaeological series. Revision of the Pech-de-l'Azé I The previous skeletochronological study of Pech-de-l'Azé I was conducted on the two main taxa identified in the level 4: the red deer and the bison. It highlighted the well preservation of the cementum increment (Armand et al., 2001) and proposed a deer slaughter during the good season and a bison hunt during the bad season (fig. 5). The revaluation has concerned the same material and the observations were made with the lambda plate inserted. Twelve teeth were analysed and taphonomic modification were identified on several of them (tab. 1). It appears that five of the twelve teeth exhibited some apatite recrystallisations and/or a lost of their collagen structure that conducted to the lost of a part of the seasonal records. For these teeth, the post-mortem modifications were too important to propose a precise age at death. In addition, in three cases, we weren't able to establish the season of death (fig. 6). Moreover a black deposit on the outer-edge of the cementum was identified. It appears that it was previously interpreted as a slow growth deposit. The use of the lambda plate has helped us to recognize it as a non biogenic material and, consequently, to correct the previous identification. Discussion By tacking into account the post-mortem modification, we were able to propose a modified seasonal spectrum of the Pech-de-l'Azé I fauna, in which four seasonal result were different from the prior study (fig. 7). The red deer hunting season wasn't really modified contrary to the bison one. At the end of this study, it appears that the bisons were killed at the end of the good season contrary to what was previously proposed. These new data modify the perception we had of the subsistence strategies by rejecting the hypothesis of a bison hunt during the winter. A second sampling in the same level (not presented here) has confirmed the results of this study (Rendu, 2007). The conclusions of this paper underline, that although most of the skeletochronological samples are not affected by these kinds of alterations, they appears to be quite common. They may have important consequences on the skeletochronological results, especially for the small samples. However, while taphonomic modifications of the cementum records might interfere with the seasonal interpretations, it is now possible to resolve these problems. Consequently, the technique developed by A. J. Stutz (2002a, 2002b) helps to magnify the reliability of one of the most accurate method to discuss the season of death of ungulate preys.
Alors que la cémentochronologie est une méthode de plus en plus utilisée pour reconstituer la saisonnalité de prédation des animaux présents en contexte archéologique, peu d'études incluent la recherche systématique des modifications taphonomiques qui peuvent affecter le cément. Ce travail propose une présentation des phénomènes de remobilisations diagénétiques de l'enregistrement saisonnier. À travers la reprise de l'analyse du niveau 4 du gisement du Pech-de-l'Azé I, nous proposons une illustration de leurs conséquences sur les études cémentochronologiques.
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Dates et versions

hal-00739821 , version 1 (09-10-2012)

Identifiants

  • HAL Id : hal-00739821 , version 1

Citer

William Rendu, Armand Dominique, Eric Ericpubert, Marie Soressi. APPROCHE TAPHONOMIQUE EN CÉMENTOCHRONOLOGIE : réexamen du niveau 4 du Pech-de-l'Azé I (Carsac, Dordogne, France). PALEO : Revue d'Archéologie Préhistorique, 2009, 21 (223-236), pp.223-236. ⟨hal-00739821⟩
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