Evidence for long-term averaging of strontium in bovine enamel using TIMS and LA-MC-ICP-MS strontium isotope intra-molar profiles

Abstract

High spatial resolution micro-sampling of tooth enamel offers the possibility of high temporal resolution isotope data to reconstruct climate, environment, diet and mobility. Questions remain about the duration and pattern of the maturation phase of enamel and the existence and direction of chronological 'time-lines'. LA-MC-ICP-MS measurements of c. 400 μm craters and TIMS analyses of transverse enamel sections of an archaeological bovine third molar were undertaken to investigate the long-term averaging of incorporated strontium. The same gradually increasing isotope profile was obtained from both approaches, indicating that the large increase in spatial resolution did not change the response profile obtained. The results suggest that even at the microscopic scale, strontium is incorporated over a period in excess of 12 months. Averaging of the input signal may result from both long-term retention of strontium in the skeleton and recirculation in the body pool, or long-term maturation of enamel on a microscopic scale. Whichever mechanism is responsible, it may not be possible to recover strontium isotope ratios with a high time resolution from cattle molar enamel unless there is a large imbalance in the amount of strontium supplied by different sources. Consequently, strontium isotope profiles may not be synchronous with those of lighter isotope systems.     

Enamel Ultrastructure of Cattle from the Quaternary Period in India

Abstract

The present paper examines tooth enamel of three species of cattle, Bos acutifrons, Bos namadicus and Bos indicus, which are supposed to have been phylogenetically related and belong to the Quaternary period. It aims to show whether in a short geological time span of 2myrs, the changing environs that cattle were exposed to during the Early Holocene have caused any microstructural changes in their tooth enamel.

Mammalian teeth exhibit a very complex arrangement of prisms in the enamel. The prisms are bundles of hydroxyapatite crystallites, arrangement of which is genetically determined and subject to evolutionary change. Hypsodonty or high crowned molars are such examples where concomitant masticatory stress factors near the enamel-dentin junction (EDJ) are known to have affected and altered the enamel microstructure in several large mammalian genera. Modified radial enamel in the deep enamel layer in some ungulates, including cattle, is an adaptive response to these stress factors which appeared much earlier (Tertiary) in the evolutionary history of these large mammals.

The cattle enamel analysed here revealed several levels of structural complexity indicating its functional designations. The schmelzmuster in cattle are formed of three enamel types: radial enamel (outer enamel), Hunter-Schreger Bands (mid enamel), and modified radial enamel (inner enamel). There is an increase through time in the percentage of Hunter-Schreger Bands (HSB), which cover up to about 68% of the entire enamel surface among recent cattle. The modified radial enamel and radial enamel do have a receding trend in the Holocene, compared to their Pleistocene ancestors.     

SIENESE ‘ARCHAIC’ MAJOLICA: A TECHNOLOGICAL STUDY OF CERAMIC BODIES AND COATINGS*

The aim of the present study is to reconstruct the production technology of Sienese ‘archaic’ majolica in the early decades of the 14th century ad . The integration of archaeological data with archived data revealed the presence of numerous workshops, suggesting that the Sienese tradition of majolica production was well developed up until the end of the 16th century. Sixty‐seven uncoated and coated waste products were analysed. The ceramic bodies were examined by OM, XRDp, SEM–EDS, XRF, ICP–OES, ICP–MS and INAA. The coatings (enamels and glazes) were analysed by SEM–EDS and Raman microspectroscopy. The results showed that ceramics were rejected due to poor control of the firing temperature (technological wastes), faulty production technology (wastes of uncertain classification) and accidents (post‐firing wastes). Finally, the analyses revealed extreme homogeneity of the ceramic bodies, indicating the continued use of the same raw material over the whole period studied.     

EXAMINING CHILDHOOD DIETS AT KAMINALJUYU,GUATEMALA, THROUGH STABLE ISOTOPIC ANALYSIS OF SEQUENTIAL ENAMEL MICROSAMPLES*

Stable carbon and oxygen isotope ratios of tooth enamel provide a means to examine nutritional changes during childhood. To date, such studies have used large enamel samples, often spanning the developmental period of the tooth. This paper reports the results of small samples drilled from first molars and premolars of human teeth from Kaminaljuyu, a Classic period city in highland Guatemala. Carbon isotopes show considerable increase between cuspal and cervical enamel for both teeth, indicating an increase in maize consumption during childhood. Oxygen isotope trends are more variable, and suggest some seasonal fluctuation. While the oxygen isotope data confirm the identification of foreign skeletons among the samples, they illustrate a need for caution when sampling teeth due to variable δ¹⁸O composition of enamel within a tooth.     

THE OPAQUE RED GLASS OF CELTIC ENAMELS FROM CONTINENTAL EUROPE

Opaque red glass was used in the Celtic world for enamels and inlays. Forty artefacts, of various dates and found in various places, have been sampled and studied. They all belong to the same type, a soda-lime-silica high lead glass coloured by crystals of cuprous oxide. There is only one subgroup: glass lumps from the Mont-Beuvray oppidum contain manganese, less iron, and less lead. This change could be the result of Roman influence. Although most of these glasses form a surprisingly homogeneous group, no conclusions as to their origin can be inferred from our present knowledge.     

THE BLUE ENAMELS IN THE BAROQUE DECORATIONS OF THE CHURCHES OF PALERMO,SICILY: FE2+‐COLOURED GLASSES FROM LIME KILNS*

Deep blue glasses coloured by octahedral Fe²⁺ cations are often reported as textbook examples of blue pigmentation. However, despite the possibility of laboratory synthesis under reducing conditions, to date there are no well‐reported occurrences of their production and use in the past. A thorough historical, ethnographic, mineralogical, and chemico‐physical investigation of the ‘smaltini di calcara’ from several baroque churches in Palermo, Sicily, has revealed that the blue enamels widely used for altar decorations in the 17th and 18th centuries are actually a unique case of ancient blue glasses pigmented by divalent iron cations in distorted octahedral coordination. This mixed‐alkali glass was accidentally produced under severely reducing conditions in the local kilns during production of lime.     

IN‐SITU ELEMENTAL AND Sr ISOTOPE INVESTIGATION OF HUMAN TOOTH ENAMEL BY LASER ABLATION‐(MC)‐ICP‐MS: SUCCESSES AND PITFALLS*

Trace element and Sr isotope data were obtained by laser ablation‐ and solution mode‐(MC)‐ICP‐MS analysis for tooth enamel from remains excavated at the New Kingdom period Egyptian colonial and Nubian cemetery site of Tombos (Sudan). Elemental abundances determined by both methods of ICP‐MS analysis yielded comparable values; however, ⁸⁷Sr/⁸⁶Sr values obtained by laser ablation were higher compared to their solution mode counterparts. This discrepancy is related to the production of a molecular interference—Ca + P + O (overlaps ⁸⁷Sr); hence the higher ⁸⁷Sr/⁸⁶Sr values recorded during ablation analyses. Laser ablation studies of enamel may provide relatively precise ⁸⁷Sr/⁸⁶Sr values rather quickly but cannot be used for accurately deciphering historical population migrations.