INTRODUCTION M icrofauna are a useful tool for the archaeologist; they can provide information about past envi- ronments, reflecting environmental change through fluctuations in species composition and diversity (Avery 1982). A taxonomic analysis, however, should be ac- companied by a taphonomic one, which allows all processes leading to changes in species composition to be understood (Andrews 1990). Dense concentrations of microfaunal ele- ments are often the result of predation, and changes in micro- faunal assemblages may be attributable to a change in pred- ator rather than environmental oscillations. In addition to being important environmental proxies, microfauna can help us gain an understanding of the use of space and to identify periods of abandonment in urban contexts. MATERIALS AND METHODS The microfaunal assemblage from the BACH Area is de- rived from the main building (Building 3) and three side spaces, Spaces 87, 88, 89 (see Figure 4.1). A total of 2,286 identifiable microfaunal elements were analyzed from the 136 prioritized BACH units (Chapter 2) (prioritized units are listed in Appendix 2.1 in the on-line edition of Last House on the Hill). These were recovered in heavy residue as part of the flotation process and were passed through 4- mm, 2-mm, and 1-mm meshes (see Figure 2.5). Elements were analyzed using a Cooke, Troughton and Simms light microscope. More detailed analysis was undertaken using an FEI Quanta 600F scanning electron microscope (SEM) in low vacuum mode at the Centre for Advanced Mi- croscopy, University of Reading. Results are presented by NISP (number of identifiable specimens), and the term “specimen” has been used to describe both complete and fragments of elements. The NISP per liter of sediment is shown in addition to the actual NISP. This is because dif- ferent quantities of sediment were sampled per excavation unit, and the NISP per liter allows the density in the differ- ent excavation units to be compared. Species identification was largely restricted to cranial elements, and identifications were made using the com- parative collections of the Harrison Institute, Kent. Speci- mens of the species Mus musculus (house mouse) were identified following the methodology of Harrison and Bates (1991), which compares the relative width of the malar process with the zygomatic arch. In Mus musculus, the malar process is narrower than the zygomatic arch, while in M. macedonicus (Macedonian mouse), the other species of Mus presently occurring in the study area, the malar process is wider than the zygomatic arch. Incisors were usually identified as “rodent,” except for Mus sp. upper in- cisors, which have a distinctive notch, allowing them to be identified to genus. The methodology for taphonomy fol- lowed that of Andrews (1990), while the methodology for identifying incisor and microtine molar digestion followed that of Fernandez-Jalvo and Andrews (1992). New cate- gories were created for murid molars, which can be found in Jenkins (2009:103). SPECIES COMPOSITION First the species composition for the whole assemblage will be discussed to give a general overview of the taxa found in the prioritized BACH units. The presentation of the re- sults are complicated by the fact that only the micro- mammalian cranial elements were identified to genus or species, while the post-crania was usually identified only as micro-mammal or rodent. Figure 10.1 shows the break- down of the elements by taxon and demonstrates that micromammals are the dominant taxa in this assemblage. Amphibians and reptiles comprise 16 percent of the total 253 CHAPTER 10 THE MICROFAUNA OF THE BACH AREA Emma Jenkins