An Integrated Approach to the Taxonomic Identification of Prehistoric Shell Ornaments

Abstract

Shell beads appear to have been one of the earliest examples of personal adornments. Marine shells identified far from the shore evidence long-distance transport and imply networks of exchange and negotiation. However, worked beads lose taxonomic clues to identification, and this may be compounded by taphonomic alteration. Consequently, the significance of this key early artefact may be underestimated. We report the use of bulk amino acid composition of the stable intra-crystalline proteins preserved in shell biominerals and the application of pattern recognition methods to a large dataset (777 samples) to demonstrate that taxonomic identification can be achieved at genus level. Amino acid analyses are fast (<2 hours per sample) and micro-destructive (sample size <2 mg). Their integration with non-destructive techniques provides a valuable and affordable tool, which can be used by archaeologists and museum curators to gain insight into early exploitation of natural resources by humans. Here we combine amino acid analyses, macro- and microstructural observations (by light microscopy and scanning electron microscopy) and Raman spectroscopy to try to identify the raw material used for beads discovered at the Early Bronze Age site of Great Cornard (UK). Our results show that at least two shell taxa were used and we hypothesise that these were sourced locally.

Non-Avian Dinosaur Eggshell Calcite Contains Ancient, Endogenous Amino Acids

“…Very ancient amino acids might yield insights into palaeobiology in addition to organic geochemistry, potentially preserving taxonomic signatures in their amino acid profiles, as seen in calcium carbonate tissue such as brachiopod shells, modern to ~3 Ma mollusc shells, foraminifera tests up to 18 Ma, and modern to recently extinct avian eggshell (Miller et al 2000, Hincke et al 1995Mann & Siedler 1999;Lakshminarayanan et al 2002Lakshminarayanan et al , 2003Crisp et al 2013;Jope 1967;Andrews et al 1984;Kaufman et al 1992;Demarchi et al 2014;King & Hare 1972;Haugen et al 1989). Such potential insight depends on the presence of sufficient variation in the original concentrations of stable amino acids of non-avian and avian dinosaur eggshells so as to be able to detect differences in original protein content after significant diagenesis and degradation.…”

The palaeontology and dating of the ‘Weybourne Crag’, an important marker horizon in the Early Pleistocene of the southern North Sea basin

“…To test the correlation between the British and continental sequences, amino acid analyses were undertaken from several critical sites. Newly-developed protocols were used to analyse the intra-crystalline components of the opercula of the freshwater gastropod Bithynia, which are composed of calcite, and shells of the marine Dog-whelk Nucella lapillus, which are predominantly composed of calcite (Penkman et al, 2008(Penkman et al, , 2011Demarchi, 2009;Demarchi et al, 2014). All samples were prepared using the procedures of Penkman et al (2008) to isolate the intra-crystalline protein by bleaching.…”

“…The IcPD data from Bithynia opercula (species undetermined) from the Norwich Crag at Thorpe Aldringham demonstrate an age older than those from Weybourne, Zuurland-2 (−63 m to −65 m) and Tegelen, whereas the data based on B. bavelensis, an extinct species known only from the Bavel interglacial at its type site, indicate its much younger age; the IcPD from both these sites are therefore consistent with the current stratigraphical interpretation. The mineral component of the shells of the marine Dog-whelk Nucella lapillus consists predominantly of calcite, although aragonite occurs in the apical and apertural regions and in the inner homogeneous layer of the shell (Demarchi et al, 2014). This predominantly calcite mineralogy offers an advantage for amino acid studies, as it is less subject to mineral diagenesis compared to shells composed entirely of aragonite (Penkman et al, 2007(Penkman et al, , 2010, and is therefore more likely to maintain the closed system of intra-crystalline protein.…”

Novel Substrates as Sources of Ancient DNA: Prospects and Hurdles

“…There is a long history of research around organic molecules preserved within the calcareous exoskeleton of marine invertebrates. Previous research has focused almost exclusively on the preservation of proteins, particularly those responsible for biomineralization [ 146 , 147 ], and the use of these proteins for amino acid geochronology [ 148 , 149 , 150 , 151 ] and more recently, taxonomic identification [ 152 ]. The potential for the calcium carbonate of marine invertebrate shell to preserve genetic material has only recently been explored.…”

“…Non-destructive and non-invasive sampling methodologies are increasingly being demanded by museums and archives in order to preserve the integrity of unique accessions and maintain sufficient material for future analyses [ 250 , 251 , 252 ]. A variety of studies have developed novel biomolecular sampling techniques for bones and teeth [ 253 , 254 ], insects [ 170 , 255 , 256 ], shells [ 152 ], books and parchment [ 249 , 257 ], and fluid-preserved specimens [ 198 ] which do not require invasive sampling. As both our extraction techniques and bioinformatic approaches improve, potentially greater amounts of information may be achieved from minute samples.…”