A conceptual model for freshwater mussel (family: Unionidae) remain preservation in zooarchaeological assemblages

Expectations for survival of vertebrate remains have been well developed and intensely studied in the zooarchaeological taphonomic literature. Taphonomic studies of shellfish remains focus on marine species and on variables relevant to remains from paleontological contexts (e.g., fossil marine beds). In this paper we develop a conceptual framework from which to derive expectations concerning the preservation of freshwater mussel remains focusing on two parameters, shell microstructure and shell shape. Shell size does not influence survivorship. Our model is validated through application to late Holocene zooarchaeological mussel assemblages from north Texas. Taphonomically robust species are important regarding zooarchaeological and biogeographic interpretations based on mussel paleofaunas, and fragile species are important indicators of whether or not an assemblage is well preserved.     

Prehistoric Molluscan Faunas of the Yazoo River,Mississippi, USA: Archaeological Perspectives for Modern Conservation

Archaeological faunal assemblages can provide data valuable to modern conservation ecology. For example, while freshwater mussels (Bivalvia: Unionidae, Margaritiferidae) are common constituents in the archaeological record of North America, today they are one of the world’s most imperiled faunal groups. Efforts to aid habitat restoration, population growth, and species reintroduction can be informed by studies of prehistoric mussel assemblages. These data can provide a historical perspective, cataloging communities as they existed prior to extensive modern impacts, thus representing an ecological baseline to be compared with modern populations. This study focuses on two late prehistoric (ca. 300–600 AD) sites on the Yazoo River, where nearly 24,000 freshwater mussel valves were recovered. Though modern data are extremely limited for the river, analysis revealed it once supported a diverse mussel community containing numerous species currently considered rare, endangered, or extinct in Mississippi. In total, the combined shell assemblages yielded 23 new river records for the Yazoo River. One species in particular, Quadrula fragosa, represents the second such occurrence in Mississippi, and bolsters its candidate status as a new state record, as argued in a recent report from a neighbouring river in the Yazoo Basin.     

The Distribution and Research Value of Archaeological Mussel Shell: An Overview from Mississippi

Abstract

Archaeological mussel shell rarely has been employed beyond paleodietary analysis in eastern North America, and most published work is site-specific in nature. Broad-scale syntheses of data on freshwater mussel shells are needed to realize the research potential of this common archaeological material. Such syntheses should also reveal gaps in our knowledge and perhaps illuminate reasons for why such gaps exist. In this paper, data on freshwater mussel shells from sites in Mississippi are gathered, and broad patterns in temporal and spatial distributions as well as site structure are discussed. The spatial data clearly suffer from survey, recovery, analytical and reporting biases, while data on temporal trends and site structure are lacking or are available at only gross levels. Given that shell data can be used in a number of research areas (e.g., biogeography, paleoenvironment, chemical sourcing, measurement of environmental disturbance), such unsystematic treatment of shell remains is unwarranted and should be corrected.     

Refit and Oxygen Isotope Analysis of Freshwater Mussel Shells from the Tillar Farms Site (3DR30), Southeast Arkansas

ABSTRACT

We investigate the link between the consumption of foodstuffs, excavation of a large pit, and disposal of waste at the Tillar Farms site (3DR30), southeast Arkansas, using refit and oxygen isotope analyses of well-preserved freshwater mussel shells from Feature 1. Only 0.13% of 7,408 valves analyzed were unidentifiable to species.The refit analysis produced 460 refits across 23 species and strongly indicates that the shell midden represents a single episode of shellfish gathering, consumption, and discard. Oxygen isotope analysis of five randomly selected shells are used as a test of the refit results. δ¹⁸O values from the five archaeological shells are compared to modern control samples of live-collected specimens from Bayou Bartholomew in winter of 2011. Refit analysis suggests the accumulation of mussel shells occurred quickly, likely as a result of one collection, consumption, and discard event. δ¹⁸O values suggest this activity took place during a single winter season.     

The Ethnoarchaeology of Juvenile Foragers: Shellfishing Strategies among Meriam Children

Recognizing children's contribution to the archaeological record may be crucial for our ideas about the role of children in human evolution. Despite this, analyses of children's activities and how they might shape archaeological patterns are almost entirely absent from discussions about site formation processes. This may in turn result from the assumption that children are either inconsequential in their foraging activities or that identifying children's activities archaeologically will be difficult if not impossible. This challenge drew our attention toward children's intertidal gathering among the Meriam of the Eastern Torres Strait as a possible agent of patterned and predictable variability in shell middens. We present an analysis of differences between the prey choice and field processing strategies of children and adults and explore an hypothesis for predicting their archaeological effects on faunal assemblage variability.     

Shell morphometry of seven limpet species from coastal shell middens in southern Africa

Measurements of shell parts and features (elements) of marine limpets can be used to derive morphometric equations for estimating total shell lengths. This is demonstrated for seven limpet species commonly found on the southern African coast. The equations can be used to reconstruct whole shell lengths for highly fragmented limpet samples in prehistoric shell middens. A linear regression model is based on measurements of all shell elements, resulting in high coefficients of determination with excellent predictive power in most cases. These morphometric equations would enable archaeologists to derive more metrical information from fragmentary archaeological material than was previously the case. We also present a case study where morphometric equations of two limpet species are applied to an archaeological sample from the South African west coast for the purpose of investigating possible biases in limpet shell preservation. We conclude that small whole limpet shells survive longer than the bigger ones in this particular case, but that many more such case studies need to be conducted in order to fully understand differential preservation of southern African limpet shells in archaeological sites.     

WHALE BONES AND SHELL PURPLE-DYE AT MOTYA (WESTERN SICILY, ITALY)

Summary. Excavations 30 years ago at sixth–fifth century BC Motya in western Sicily produced a unique assemblage of four Sperm whale vertebrae, crushed purple-dye shells, and stone tools. The whale vertebrae were the platforms for breaking the shells. Here I discuss recent sightings of Sperm whales in the Mediterranean, the archaeological evidence for whaling in the Mediterranean, and possible whale products available, as well as Italian shell purple-dye evidence.     

A biometric technique for assessing prehistoric freshwater mussel population dynamics (family: Unionidae) in north Texas

Biometry is useful for a suite of analyses relevant to zooarchaeology, which include analysis of mortality profiles, taphonomy, paleoecology, among other purposes. Here, size-age prediction models are developed for 10 freshwater mussel species found in north Texas to develop a method for studying paleoenvironmental conditions. Shell length is often used to evaluate the structures of modern mussel populations, but its use on paleozoological specimens is not feasible because complete shells rarely preserve. Instead, pallial line-to-lateral teeth length (PLL) and pseudocardinal teeth-to-pallial line length (PSP) are evaluated as proxy measures for shell length. Linear regression models based on PLL and PSP using modern mussels demonstrate that they are accurate proxies of shell length for multiple species from a variety of habitats. In addition, ontogenetic-age structures for a modern sample and for two late Holocene assemblages from north Texas are developed using PLL and PSP. These techniques are useful tools for evaluating past ecological conditions of freshwater mussel populations when large samples are available for study, which expands analytical potential of zooarchaeological studies of prehistoric unionid remains.     

The potential of chironomid (Insecta: Diptera) larvae in archaeological investigations of floodplain and lake settlements

The head capsules of chironomids (Insecta: Diptera) are well preserved in sediments and can be recognised to a high taxonomic level, usually genus and sometimes species. Work on lake sediments has shown that they can be accurate indicators of water temperature, oxygen regimes, and nutrient status (particularly total phosphorus and chlorophyll-a), as well as heavy metal pollution. No systematic chironomid analyses, however, have previously been undertaken on archaeological deposits. In order to address this we assessed the use of chironomids in three types of archaeological deposit; firstly, a lake core at the edge of a lake settlement (crannog), secondly, a palaeochannel infill adjacent to a multi-period settlement site and lastly, a Roman well deposit from a floodplain environment. The chironomid assemblages are shown to vary significantly both between and within the sites and reflect the immediate environment and the adjacent area. The lake sediment assemblage reflects the construction of the crannog through elevated levels of organic detritus, wood and woody debris. The palaeochannel assemblage reveals changing natural conditions and nutrient enrichment probably associated with settlement during the Saxon period. The well assemblage is taxonomically restricted and indicative of organic debris, dead plant material, animal dung and possibly human effluent deposited after abandonment of the well. Dry storage of the palaeochannel and well sediments for several years did not appear to affect the concentration or state of preservation of the head capsules. The chironomid reconstructions are shown to provide an additional indicator of human activity which has the potential to provide quantitative data on the character of aquatic environments associated with archaeological sites.     

Human impacts on ancient shellfish: a 10,000 year record from San Miguel Island,California

We use measurements of more than 11,000 marine shells from 41 archaeological components to construct a 10,000 year record of human impacts on ancient mussel and abalone stocks on San Miguel Island, California. General reductions in the mean size of mussel and abalone shells gathered through time are attributed to growing human population and predation pressure. Based on comparison with historically documented changes in shellfish communities caused by the local extinction of sea otters in the 19th century, changes in mean shell size and the abundance of other shellfish species may have been facilitated by Native American predation on sea otters as early as 7500 years ago. Despite having measurable impacts on local ecosystems, Native Americans on San Miguel harvested huge quantities of shellfish throughout the Holocene. Such long-term harvests appear to have been sustained by an early emphasis on fishing at lower trophic levels, by periodically shifting village locations, and by intensifying the use of finfish and sea mammals through time. This pattern of “fishing up the food web” contrasts with many modern fisheries, suggesting that the study of ancient fisheries can help us better manage our own endangered coastal ecosystems.     

Disentangling long bones of foxes (Vulpes vulpes and Alopex lagopus) from arctic archaeological sites

To discern the presence of two anatomically close species within an archaeological assemblage is always a problem for the analyst. A particularly interesting case is the distinction between the red fox (Vulpes vulpes) and the arctic fox (Alopex lagopus), which is often determined using non-rigorous criteria and producing results that must be regarded with caution. Classical methods for separating these two species and determining sexual dimorphism, and eventually the sex ratio, such as analyses using uni- and bivariate plots, are based on arbitrarily fixed limits between sexes. In this text, a more robust statistical method termed mixture analysis (MA) is used to determine the species of limb bones from foxes. First, the MA is applied to a sample of each species using metric data taken from a collection of present-day fox skeletons. Afterwards, the MA is applied to archaeological samples dated to the Dorset period and retrieved from the Tayara site (near Salluit, South Hudson Strait, Nunavik). The results clearly demonstrate that the greatest length (GL) of long bones, especially the humerus and tibia, is the best measurement for distinguishing the species, followed by the distal breadth and the proximal breadth; and that GL is better suited for sexing foxes. The results of MA applied to the Tayara site collection lead to the conclusion that the red fox is present along with the arctic fox among the assemblage, and that there is no fox body size change during the last two millennia in the Eastern Arctic.     

A comparison of multiple proxy data sets for paleoenvironmental conditions as derived from freshwater bivalve (Unionid) shell

Freshwater mussel shells from Middle and Late Holocene strata at an archaeological site in Mississippi, U.S.A., are examined for morphological and chemical differences that could be related to changing paleoenvironmental conditions. Although significant differences are noted, the different data sets provide contradictory or unclear results, suggesting that reliance upon single data sets is an unwarranted practice.     

Neolithic fish remains from the freshwater shell midden Riņņukalns in northern Latvia

The Neolithic site Ri??ukalns in the Lake Burtnieks/River Salaca area in northern Latvia is the only freshwater shell midden in the eastern Baltic Sea area. An excavation carried out in 2011 revealed an intact stratigraphy with alternating layers of unburnt and burnt mussel shells and yielded various kinds of archaeological finds, among them several thousand fish remains. To gain an understanding of the fish species and specimens caught by the Neolithic settlers, and to discern any temporal development in the fish species composition, we analysed fish remains from different sections and layers. Results from both the archaeozoological and stable isotope data, give evidence for a change in the relevance of fish species during the period of use, and they also provide information for reconstructing the former river and lake hydrology in the vicinity of the midden. The Stone Age landscape seems to have been very similar to the present situation, so that the study area has been an extraordinarily stable ecosystem for more than 5000 years. Comparisons with the results of recent monitoring programmes, long-term changes since Medieval times, and written sources from the 18th century, show that the fish species community is almost unchanged since the Stone Age. This underlines the importance of the region in nature conservation.     

Red abalone collecting and marine water temperature during the Middle Holocene occupation of Santa Cruz Island,California

Oxygen isotope values derived from prehistoric mussel (Mytilus californianus) shell calcite are used to determine whether sea-surface temperatures in the vicinity of the Punta Arena site (CA-SCRI-109) on Santa Cruz Island, California, were cooler than present between 6300 and 5300 cal BP. This site and others in the western sector of the island dating to this period are distinctive because of the presence of large red abalone (Haliotis rufescens) shells, a species that historically has been subtidal around Santa Cruz and the other northern Channel Islands. Comparison of temperature values derived from archaeological shells with those from modern mussel shells, along with water temperatures derived from satellites, indicates that waters were cooler during the 6300 to 5300 cal BP period. These results are consistent with a previous study and support the interpretation that collection of red abalone during the 6300–5300 cal BP period was partly the result of cooler water temperatures that made this large mollusk more available to foragers in the intertidal or shallow subtidal zone.     

Intensification of shellfish exploitation: evidence of species-specific deviation from traditional expectations

As modern humans grapple with the repercussions of their extensive environmental impacts, archaeologists are increasingly looking toward the past to understand the nature and extent of prehistoric human impact on the environment. Many researchers rely heavily on archaeological correlates of resource intensification as a proxy measures of resource depletion, a profound and often catastrophic human impact. However, the traditional conceptualization of the archaeological correlates of shellfish intensification disregards a large amount of species-specific variation. This paper presents archaeomalacological data from Santa Cruz Island, California. The shell midden deposits CA-SCRI-480 contain a high density of Tivela stultorum (Pismo clam). Statistical analysis of the shellfish assemblage reveals significant variation in both the size and quantity of Pismo clam that people collected through time. This paper investigates this unique patterning with due consideration of the natural ecology and life history of the species and illustrates species-specific deviation from the traditional archaeological correlates of shellfish intensification. Increased collaboration with ecologists and biologists can help refine models of intensification when necessary in order create more sophisticated understanding of prehistoric human–resource interactions.     

Morphometric Analysis of the Yellow Clam (Amarilladesma Mactroides) to Interpret Fragmentary Archaeological Specimens

Mollusks were an important component in the diet of the hunter-gatherer groups that inhabited the coastal zones of South America during the Holocene, as recorded in the littoral shell and archaeological sites distributed from Brazil to Argentina. Although the shells are relatively resistant to physical and chemical agents, they are also fragile and various post-depositional processes affect their integrity. Puente de Fierro is an archaeological site located in the south of Buenos Aires province (Argentina), in which remains of the yellow clam (Amarilladesma mactroides) were recovered totally fragmented. We investigate if a morphometric model based on modern clams could be applied to estimate shell size and individual biomass of archaeological clams. Linear regression models reveal a high correlation between the chondrophore length and the shell length, and therefore, the individual biomass of the yellow clam.     

The PalaeoEnvironments and ARchaeological Landscapes (PEARL) project: Recent findings from Neolithic sites in Northern Oman

The PalaeoEnvironments and ARchaeological Landscapes (PEARL) research project is a joint German–British project with the principal objective of developing a framework of past human occupation and landscape change in south-eastern Arabia. Fieldwork during 2018 and 2019 involved the systematic survey and excavation of sites in the Rustaq and Ibri regions of Northern Oman, with the aim of establishing the nature and timing of human occupation and landscape change during the Early Holocene period (c. 10,000–7,000 years BP). Further to the findings previously reported, results from recent excavations of the site Hayy al-Sarh in Rustaq revealed the presence of animal remains, stone and shell beads and stone structures, indicating a large Neolithic settlement with burial areas. In addition, preliminary excavations at a rock shelter site near Ibri have revealed stratified archaeological remains, including a Fasad-type assemblage. Future fieldwork will further develop archaeological and palaeoenvironmental records to help build a framework for studying cultural and natural developments in Northern Oman.     

Trampling vs. Retouch in a Lithic Assemblage: A Case Study from a Middle Stone Age Site,Steenbokfontein 9KR (Limpopo,South Africa)

At the site of Steenbokfontein 9KR, virtually 80% of the lithic blanks presented retouch—an extreme proportion for Middle Stone Age assemblages. The high percentage of putative retouch led us to investigate whether post-depositional processes played a role in the preservation of the lithic assemblage. We designed and performed an experiment that reproduced all the archaeological conditions inferred from the site formation analyses to determine if the archaeological assemblage was trampled or retouched. We defined several qualitative attributes and studied both trampled and retouched experimental samples, and compared them to the archaeological material. We subsequently performed different statistical analyses and a correspondence analysis with all the macro qualitative attributes that we defined. We were then able to discern which attributes were the most eloquent variables and assess the usefulness of a multivariate analysis in discriminating between trampling and retouch.     

EVALUATING CONTEMPORANEITY AND POST‐MORTEM AGE OF MALACOLOGICAL REMAINS USING SCLEROCHRONOLOGY AND DENDROCHRONOLOGY*

Sclerochronology and dendrochronology are based on series of incremental skeletal and cambial growths that have been correctly aligned in time via cross‐dating (i.e., incremental dating through synchronization of the growth variability on a visual and statistical basis). Here we report a study of the shell increments of two anthropogenic death assemblages of freshwater pearl mussel (Margaritifera margaritifera) originating from Finnish Lapland. First, we cross‐dated a new sclerochronology from an assemblage of river pearl mussel shells with unknown post‐mortem age. Second, this chronology was cross‐dated with the previously published sclerochronology of the same species and geographical source. Third, the composite of the two sclerochronologies was compared to dendrochronologies from Lapland. Temporal association of the two types of chronologies was markedly high, as confirmed by t‐values of 7.1 and 8.9, which are well above the acceptable limit of 3.5. Our study demonstrates the potential of sclerochronological and dendrochronological materials and techniques in assessing the contemporaneity (i.e., temporal overlap) and post‐mortem age of archaeomalacological deposits. In the palaeontological context, these results also show the wider possibility of dating shells with a large number of annual increments from natural deposits.     

The Ethnoarchaeology of Reptile Remains at a Lake Turkana Occupation Site, Kenya

The role of reptiles in hominid hunter–gatherer subsistence in Pleistocene Africa has been largely overlooked. This study examines the reptile component of a modern lake shore camp (site 20) assemblage of low archaeological visibility. Site 20, located on the eastern shore of Lake Turkana, has been observed from its creation to burial. The site is an ideal modern analogue for the interpretation of African prehistoric archaeological sites. Patterns of element loss, and patterns of bone modifications, namely burn, cut and slice marks, are examined. From this baseline data, three conclusions are drawn regarding the interpretability of reptile remains found at archaeological lakeside sites: (1) the MNI of crocodile remains at a site is likely to be similar to the original number of individuals which contributed to the deposited assemblage; (2) the MNI estimates of the turtle component will be much less than the original number of individuals in the deposited assemblage; and (3) patterns of bone modifications can be related to hominid food procurement and processing activities.