Radiocarbon Wiggle-Match Dating in the Intertidal Zone

Radiocarbon wiggle-match dating is a technique that can combine the versatility of radiocarbon dating with chronological information from tree-rings. This makes it useful in contexts where timbers are preserved, but dendrochronological dating is impossible. As intertidal and marine timbers are waterlogged, this can favor their preservation and hence allow wiggle-match ¹⁴C dating, which can be of significant help in deriving relatively precise chronologies for a range of coastal structures. As the technique depends on making multiple radiocarbon measurements towards a single date, efficiency in application is the key and hence a number of practical considerations need to be taken into account in advance of conducting a dating program. This paper discusses some of these practical concerns and reviews them in the context of the intertidal crannogs in the Firth of Clyde on the west coast of Scotland.     

The urban ecology of Iron Age Tel Megiddo: using microvertebrate remains as ancient bio-indicators

The potential of microvertebrate remains for reconstructing the paleoecology of urban sites remains largely untapped except for extensive research carried out at Roman and medieval sites in Britain. We apply taphonomic and ecological approaches to analyzing an assemblage of microvertebrate remains from the Iron Age IIA of Tel Megiddo, Israel. Sampling in a dense residential area including house floors and various fills produced 1080 identifiable specimens including fish, mammal, reptile and bird remains. The mammalian remains show a number of distinct patterns pointing to accumulation from the community of small animals which lived and died on-site. These patterns include evidence for fragmentation due to trampling and presence of burned specimens. The mammalian remains also differed in their taphonomy from an assemblage from Early Bronze Age II Megiddo which originated from predator accumulation during a period of abandonment. These analyses point to an especially low taxonomic diversity in the Iron Age residential assemblage suggesting that the urban environment of Megiddo supported a unique community of small mammalian animals. This differs markedly from ecological conditions in modern day cities which in some cases show greater than background levels of diversity and suggests a dense, homogenous urban environment. We suggest that reconstructing the evolution of urban fauna in greater detail will provide a sensitive tool for tracing historical processes of growth, decline and increasing complexity of urban sites in the Near East as well as other regions of the world.     

The holotype individual of the ornithopod dinosaur Leaellynasaura amicagraphica Rich & Rich, 1989 (late Early Cretaceous,Victoria, Australia)

Doubt has been cast upon the association of the skull roof and postcranial bones, originally regarded as part of the same individual as the holotype, the left side of the skull, of Leaellynasaura amicagraphica Rich & Rich 1989. The reasons given for these doubts, the form of the prefrontal and the proportions of the supratemporal region being inconsistent with the holotype, are imprecise. The association is supported both by the morphology of the parietal and jugal, which are similar to those of Dryosaurus, and the unique sedimentological setting.     

Growth,decay and burial compaction of Dickinsonia,an iconic Ediacaran fossil

Retallack, G.J., September, 2007. Growth, decay and burial compaction of Dickinsonia, an iconic Ediacaran fossil. Alcheringa 31, 215-240. ISSN 0311-5518.

Dickinsonia is a Neoproterozoic, Ediacaran fossil, variously considered a polychaete, turbellarian or annelid worm, jellyfish, polyp, xenophyophoran protist, lichen or mushroom. Its preservation as unskeletonized impressions in quartz sandstones has been attributed to a Neoproterozoic regime of aerobic decay less effective than today, microbial pyritization much nearer the surface than today, or agglutinate-mineralization as in xenophyophorans. However, the great variation in thickness independent of width or length of South Australian Dickinsonia is evidence of decay like the wilting of a fossil leaf, lichen or mushroom, but unlike clotting and distortion during decay, wilting or osmotic shrinkage of modern and fossil worms and jellyfish. Decayed specimens of Dickinsonia arrayed in arcs have been interpreted as slime trails or tumble tracks, but can also be interpreted as rhizinous bases of decayed crustose lichens or mushrooms arranged in fairy rings. Dickinsonia is interpreted to be sessile because adjacent specimens show reaction rims indicative of competitive interaction, and because no overlapping well-preserved specimens have ever been found. Folded and bent Dickinsonia reveal firm attachment and limited flexibility, but no brittle deformation indicative of pyritic, sideritic or calcitic ‘death masks’ or xenophyophoran agglutinate skeletons. Dickinsonia was resistant to compaction by overburden, like fossil lichens such as Spongiophyton and Thucomyces, and more compaction-resistant than fossil logs, jellyfish or worms. Dickinsonia also shows indeterminate growth like lichens, fungi, plants, xenophyophorans and colonial animals. Growth, decay and burial compaction of Dickinsonia were more like those of plants, lichens and fungi, than of worms, jellyfishes or anemones.

G.J. Retallack [gregr@uoregon.edu], Department of Geological Sciences, University of Oregon. Eugene, OR 97403-1272, USA; received 18.11.05, revised 23.3.06.     

Particle size distribution of lithic assemblages and taphonomy of Palaeolithic sites

Lithic debris derived from knapping and used tools can be assimilated to simple sedimentary particles that may undergo size sorting when exposed to geomorphic processes such as streamflow or overland flow. Sorting can be identified by comparing the size distribution of archaeological assemblages to that of experimental core reduction sequences. A new database including different types of raw material (mainly flint and quartzite) and Palaeolithic debitage (blade, Levallois, discoid, on anvil, and shaping) has been built for this purpose. Palaeoeskimo data have also been added to illustrate microlithic industries. For all the debitages and raw materials, the particle size of knapping products >2 mm in width fits with a power-law distribution and shows only minor fluctuations, the range of which is always <15% between experiments (all steps of the chaîne opératoire included up to the final tool). A lithic assemblage derived from block/core knapping or blank/preform production will display a particle size distribution close to the experimental distributions if not subsequently modified. Modifications may originate either from sedimentary processes or from anthropogenic factors. To help distinguishing amongst these, data on the impact of both water flows on sedimentary particles or experimental assemblages, and anthropogenic processes such as importation-exportation (of core, preforms or finished tools) or uneven spatial distribution of the different steps in core reduction and tool production within a site, are reviewed. By contrast to anthropogenic modifications, sedimentary processes are generally typified by strong impoverishment in or selective accumulation of fine-grained (<10 mm) artefacts together with a low intra-site variability (spatial homogenization) or a downslope size trend. Archaeological case studies taken from French Palaeolithic site are then detailed. Evidence for lithic redistribution implies that care should be taken in archaeological site analysis since sorting may impact significantly the initial techno-typological balance of the assemblage.     

The taphonomic attributes of a Late Cretaceous plesiosaur skeleton from New Zealand

The pre-burial history of a partial elasmosaurid plesiosaur skeleton is reconstructed from analysis of the distribution and modification of bones preserved in a calcareous concretionary mass. The specimen lacks the skull, cervical vertebrae, left limb bones and some girdle elements, but the remaining bones are interpreted to have been deposited on the sea floor from a semi-buoyant carcass and their relative positions modified by the action of scavengers. Bioerosive agents caused loss of bone, particularly on joint surfaces and vertebral centra, as the carcass lay exposed on the sea floor, perhaps for several years before burial.     

Relax,Don’t Do It: A Future for Archaeological Monitoring

Preservation in situ and the monitoring of archaeological sites have become important themes since the acceptance and implementation of the Valletta Treaty. In the last few decades, our knowledge of degradation processes has increased manyfold, and a range of techniques have been tested and applied for use in both assessment and monitoring. Despite these successes, all is not well. First, we have little notion of the speed of the decay processes involved. This makes it difficult to distinguish between acute and protracted degradation. Apart from that, many assessments and subsequent monitoring projects rely (too?) heavily on complex and costly specialist technology. For any future preservation — in situ — projects low-tech observations together with best estimates of decay rates and archaeological site information should be combined to make an accurate assessment of the effects of decay on the archaeological record. Monitoring for preservation purposes is only appropriate if (1) decay processes occur within a relevant and measurable time scale, and (2) if mitigating actions can be taken or preservation ex situ can be performed (i.e. a rescue excavation) if significant degradation takes place.     

Methodological problems in the analysis of fossil non-artifactual wood assemblages from archaeological sites

The analysis of fossil wood fragments is often undertaken in relation to the archaeological excavation of a site. However, such analysis does not yet appear to have the strong methodological foundation that the investigation of many other classes of palaeoenvironmental evidence (e.g. seeds and pollen) have. Consequently, it is difficult to evaluate the value of fossil wood analysis at an archaeological site. Using data regarding non-artifactual wood assemblages at one site in southern Scotland, the relative merits of possible analysis are described and discussed. The results from such analyses tend to fall into two broad groups: (I) those of relatively high reliability, and (2) those of relatively low reliability. The results in the former group are often based on moderately secure methodology and tend to provide relatively non-interpretative information (e.g. species lists). On the other hand, those in the latter group are more often based on insecure interpretive methodology and provide relatively more stimulating information, such as evidence for prehistoric woodland management. There are many reasons for this situation, and these are discussed. In conclusion, it is argued that to increase the reliability of results in the second group (in particular), a full understanding of the taphonomy of non-artifactual fossil wood assemblages is needed, and that once this is available attention can then be paid, as elsewhere in environmental archaeology, to the problems of providing statistically valid samples for analysis.     

Bone surface modifications in zooarchaeology

Cutmarks made by stone tools, conchoidal flake scars from hammerstone percussion, carnivore tooth marks, striations from sedimentary abrasion, and other surface modifications on bones from archaeological sites constitute a crucial body of evidence for investigating the role of human behaviors and of nonhuman taphonomic processes in site formation. This paper describes the various kinds of bone surface modifications produced by humans and by nonhuman processes and assesses the current status of bone surface modification studies with regard to such issues as the need for greater analytical standardization, the selection of instruments for examining bone specimens, tactics for identifying the origins of marks on bones, and strategies for inferring human behaviors.     

Urban small vertebrate taphonomy: a case study from Anglo–Scandinavian York

Sampling of deposits at the Queens Hotel site, York, produced a substantial number of small terrestrial vertebrate remains from the Anglo–Scandinavian features. By studying bone surface modification, fragmentation and skeletal completeness as taphonomic indicators, it was possible to demonstrate that the assemblage had resulted from two very different modes of accumulation and deposition. Refuse pits situated within the boundaries of the tenements had acted as accumulators of the fragmented and abraded small mammal and amphibian bones that existed as a sub‐surface death assemblage within the local environment. In contrast, the excellent preservation and skeletal completeness of numerous frogs recovered from the basal fill of a wooden well could be accounted for by their direct entry into the burial environment as a result of pit‐fall trapping. This paper also discusses the implications that the temporal and spatial variation in deposition demonstrated by the micro‐faunal remains has for the reconstruction of local ecological and environmental conditions within this site, and for other such sites. Copyright © 2001 John Wiley & Sons, Ltd.