The Animal Bones from Battlesbury Bowl
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The Animal Bones from Battlesbury Bowl Ellen Hambleton and Mark Maltby School of Conservation Sciences, Bournemouth University Introduction: Methods of Recording and Quantification All bones and teeth recovered from the excavations were examined and where possible identified to species and skeletal element using reference material from the comparative skeletal collection housed in the School of Conservation Sciences, Bournemouth University. Where appropriate, the following information was recorded for each fragment: context; element; anatomical zone; % completeness; fragmentation; surface condition; gnawing; fusion data; porosity; tooth ageing data; butchery marks; metrical data; other comments such as pathologies or association/articulation with other recorded fragments. The information was recorded onto a relational database (Microsoft Access) and cross-referenced with relevant contextual information such as date and feature type. Groups of four or more bones that belonged to the same skeleton (i.e. articulating bones or elements closely matched by size and age) were assigned an ‘Associated Bone Group number’. In some instances several separate bone groups were recorded for the same individual, for example where there were several articulating element groups from different body areas but with no clear proof that they came from the same carcass. A summary form was also created for each context. This contained brief notes about preservation; a preservation grade (very good; good; moderate; poor; very poor); the approximate size of the assemblage (very small - <10 specimens; small – 11-49 specimens; medium 50-99 specimens; large – 100-499 specimens; very large - >500 specimens); a list of species represented ranked by order of frequency; notes about highlighted specimens and general comments about the assemblage; bone group number and brief details about these groups. This database, together with supporting charts, tables and photographs forms part of the site archive. Methods of quantification employed for the Battlesbury faunal assemblage include the number of identified specimens (NISP), whole bone equivalents, the minimum number of individuals (MNI) and the minimum number of elements (MNE). These methods are described below and the various merits and disadvantages of these have been discussed elsewhere (Hambleton 1999:33-35). NISP is the method of quantification most commonly used in British Iron Age faunal studies and as such provides a means by which to compare Battlesbury with other Iron Age assemblages. The relative abundance of species in the Battlebury assemblage is discussed below with the emphasis on NISP counts but MNI and MNE calculations are also considered. Fragment counts of all identified specimens (NISP) include dorsal ends of ribs, vertebral bodies, and fragments of long bone shaft and skull provided they could be securely identified to species. Specimens represented by several fragments that could be rejoined were recorded as a single unit and the fragmentation was noted. Minimum numbers of elements counts (MNE) were calculated for a suite of bone elements representing all areas of the skeleton. MNE was derived from the most common zone of a bone and corrected to account for the frequency of each bone in the skeleton. Up to nine zones were allocated for each anatomical element in a recording method adapted from Dobney and Rielly (1988). Where present, each of those zones was recorded, as were fragments represented only by “un-zoned” fragments. The MNE counts for each element were summed to provide an overall MNE count for each species. Overall minimum numbers of individuals (MNI) for each species were derived from the MNE of the most common element. Side of the body was not taken into account for the MNE and MNI counts. The Size of the Assemblage A total of 27,824 fragments of animal bone and teeth were recovered from 663 contexts during excavations at Battlesbury Bowl. The majority of the assemblage (22,485 fragments) was recovered by hand, while a further 5,339 fragments were retrieved from sieved environmental samples (Tables 1-2). From the hand-recovered assemblage, 9,316 fragments were identified to species, which represents 41% of the overall assemblage. The proportion of identified fragments (only 10%) was substantially lower among the sieved samples. In terms of number of identified fragments, Battlesbury’s faunal assemblage is of a similar order of magnitude to Winnall Down (Maltby 1985a) and is one of the largest collections of Early and Middle Iron Age animal bones from Britain. Phased features account for 90% of the bone material, with only 2,067 fragments coming from unphased contexts. Only 19 fragments of bone belonging to the Early Bronze Age were recovered and the rest of the assemblage came from Iron Age phases 1-4 ranging from Early to Middle Iron Age date. Bone was recovered from a variety of feature types but by far the most common were pits, which yielded 82% of the faunal assemblage. A further 13% of bone fragments came from ditches, gullies and other linear features and 3% from postholes. Other bone-yielding feature types include ovens, hearths and slots. The Battlesbury Bowl excavation area runs in a long narrow strip, within which features were grouped spatially into four main clusters running from South (feature group 1) to North (feature group 4). The southernmost cluster, feature group 1, yielded the largest proportion of the faunal assemblage (40%). Feature group 2 was the next most abundant area of the site and produced 27% of all faunal remains while 20% came from feature group 3. The northernmost cluster, feature group 4, produced only 13% of the total assemblage. The above figures are based on both hand-collected and sieved totals. Table 3 provides a more detailed breakdown of hand-collected bones by phase, feature type and location. It can be seen that the majority of the bones in most phases came from 388 pit contexts. Indeed pits provided all the bones for Phases 1 and 4 and 99% of the bones for Phase 1-2 and Phase 3. Only in Phase 2 did assemblages from ditches figure significantly, 87 contexts providing 67% of the sample compared with only 33% from pits. The bias towards pit assemblages is unsurprising given the number of pits excavated. Unfortunately most of the 140 contexts from postholes that produced bones are unphased. However, their contribution to the overall assemblage is minimal. The average number of bone fragments from contexts containing bone varies significantly between feature types. Overall, postholes produced only about four bones per context, ditch contexts 29 and pits 48. Of course, these figures do not take into account variations in volumes of soil excavated but excavation records also show that the weight of bones recovered tended to be greater in pits, although there is a great deal of variation. There is some evidence that the rate of deposition increased in the later phases. Average bones per bone-producing context ranges between 27 and 44 in the earlier assemblages but rises markedly to 75 bones per context in Phase 3 pits. In terms of location, the size of the hand-collected assemblage decreases between feature group 1 and feature group 4 overall but this of course varies significantly between phases. The small number of bones from Early Bronze Age deposits are all from feature group (cluster) 4, whereas all the Phase 1 assemblage is from feature group 3. Bones assigned to Phase 1-2 were found in all four areas, with feature group 3 providing 40% of the bones, followed by feature group 2 (30%), feature group 1 (18%) and feature group 4 (12%). In contrast, feature group 1 provided the majority of bones (74%) in Phase 2. These include most of the bones from ditches. Feature groups 3 and 4 produced 19% and 7% respectively of the remaining faunal sample from this phase. Bones assigned to Phase 2-3 mainly derive from feature groups 2 (48%), 1 (30%) and 3 (22%). The largest sample of bones (NISP =7,848) is from Phase 3 contexts. 39% of these are from feature group 1, 37% from feature group 2, 17% from feature group 4 and 7% from feature group 3. All the bones from Phase 4 were found in five pit contexts in feature group 1. Species Representation - Introduction The assemblage is dominated by domestic species. NISP counts show that domestic species (sheep/goat, cattle, pig, horse and dog) make up 94% of the hand-recovered assemblage (Table 1). The wild species, which make up the remaining 6%, include some larger species (red deer, roe deer, fox and badger) as well as a variety of wild birds, small rodents and amphibians. Within the hand-recovered domestic species assemblage, sheep/goat remains are the most abundant, followed by cattle, pig, horse and dog in order of abundance. This was true for all three methods of quantification used (Table 4). There are slight differences in the percentages of the different domesticates depending on the quantification method used. NISP counts of fragmented assemblages have a tendency to under-represent sheep/goat, pig and other species of similar size in comparison with cattle and horse. This reflects the fact that cattle and horse bones tend to break into larger, more readily recovered and identified fragments while the bones of smaller species, when fragmented, are often less easily identified or missed during hand recovery. Sheep/goat and similarly sized mammal fragments are much better represented in the sieved sample (Table 2) than in the hand-recovered sample, which supports the suggestion that differential fragmentation and retrieval biased the hand-collected sample in favour of larger bones. Minimum Numbers counts (MNE and MNI) tend towards a slightly better representation of sheep/goat and similarly sized species in fragmented assemblages such as Battlesbury, as by including only non-repeatable elements in the counts some of the problems of differential fragmentation between species are reduced.