Introduction

Taphonomy is a discipline common to many fields, like paleontology, geology, paleoecology, or archaeology. Its basic goal is to understand the transition of organic materials, for example, bones or soft tissues, from the biosphere to the lithosphere (Lyman 1994). Taphonomic information is routinely used by archaeologists to assess the quality of archaeological data, to evaluate the loss of cultural and ecological information, to pursue paleobiological questions, and sometimes also to acquire paleoecological information (Gifford 1981; Behrensmeyer 1993; Lyman 1994; Marean 1995). In other words, the conditions which are adequate for the formation of fossils are a central concern of taphonomy. Archaeological applications are usually focused on the preservation of bones, but they also cover cases involving transformations of lithic tools, pottery, or other kinds of materials. In most cases local scales of analysis are used – usually, the site – and indeed those scales are adequate to perform most of these tasks. The literature is full of successful examples of application of taphonomic analysis at a local scale (Pickering et al. 2007; Stuart & Larkin 2010). However, the fact that the scale at which most archaeological problems are usually stated is regional is a valid reason to also advocate for a regional scale of taphonomic analysis (Borrero 1988).

Definition

The basic goal of regional taphonomy is to understand the dynamics of environments at large spatial scales, particularly the processes responsible of bone accumulations. An accumulation of bones is usually defined as any surface or stratigraphy occurrence of vertebrate remains of more than one individual in a well-circumscribed area, around 100 m2 (Behrensmeyer 1991: 293), and it is the result of a variety of processes. The regional distribution of bone accumulations and its causes constitutes the central subject of the analysis (Haynes 1982; Behrensmeyer 1983; Borrero 1988). These bone accumulations may be the result of the activities of one or more agents, and one important task is that of separating those agents in an effort toward understanding the causes behind the different bone accumulations. Taphonomic analysis can help to separate fossil bone accumulations created by hominins, carnivores, water, or other varied agents (Haynes 1980; Behrensmeyer 1991; Gutiérrez et al. 2010). On the other hand, beyond the identification of the depositional agents, a regional taphonomy may provide an understanding of the impact of the recent natural “bone rain” on the regional archaeological record. The formation of palimpsests and other issues of contamination of archaeological and recent bone assemblages can be assessed in this way. In other words, an understanding of what bones can be used for a cultural discussion and what bones inform on modern and fossil natural processes at different loci is the expected result of a regional taphonomy.

Historical Background

Taphonomic research in Tierra del Fuego provides a substantial example of some of the properties of a regional taphonomy. This example highlights the importance of the processes of contamination of archaeological sites with modern bones and the necessity to understand the causes creating those palimpsests. The San Pablo region in the Atlantic coast of Tierra del Fuego, Argentina, is characterized by extensive Nothofagus sp. forests that alternate with peats and prairies. This region was actively used by hunter-gatherers during the Late Holocene. It is also a place regularly inhabited by guanacos (Lama guanicoe). This study showed that most of the known archaeological sites of that region dated between approximately 300 BP and present were contaminated with recently deposited guanaco bones. Longitudinal observations made along several years confirmed the vertical migration of recently deposited guanaco bones contaminated many archaeological assemblages (Borrero 1990). This problem was aggravated by the fact that the modern bones that were contaminating the archaeological assemblages were highly fragmented. Similar mixes of old and recent bones were also noted when other archaeological assemblages were studied on the island or in Patagonia. Given the fact that guanacos were also the main prey for prehistoric hunter-gatherers, the separation of archaeological and “natural” bones is generally difficult to achieve. Generally speaking, taphonomic research produced a suite of taphonomic principles – rates of weathering, ranking of bone destruction, bone selectivity by different carnivores or by running water, etc. – that can be used to separate recently deposited bones from archaeological bones (Borrero 2007). This separation is crucial to acquire a trustable list of the guanaco parts selected for human consumption. Similar problems involve other species in other places (Behrensmeyer 1991; Lyman 1994).

Key Issues/Current Debates

Knowledge about the regional distribution of the archaeological materials is important for any regionally oriented taphonomic research program (Dunnell & Dancey 1983). In other words, this is the only way to know at which places artifacts and natural bones had the potential to overlap in space and also at which places good bone preservation is to be expected. The best way to do this combines taphonomic and geoarchaeological work.

The more useful data collection strategies are those that at the same time will record both archaeological and taphonomic information. Surface bones recorded in transects or blocks (Behrensmeyer 1983) need to be classified by species, element, completeness, degree of disarticulation, abrasion stage, weathering stage, and classes of damage (carnivores, rodents, etc.) (Lyman 1994). When possible, evidence of cause of death, age at death, presence of associated tracks, feathers or scats, and type of substrate must also be recorded. The potential for burial can be evaluated not only by using soil probes but also by analyzing the correlation between weathering stages and bone burial – usually defined as 50 % or more of the element covered by sediments (Behrensmeyer 1991). Frequency information is usually transformed into densities per square meter to facilitate comparisons. The archaeology of the places that show high risk of bone contamination needs to be stratigraphically examined using test pits. In this way, by using the locally recorded fossil and taphonomic information and general taphonomic principles, the degree of bone contamination can be assessed.

Other regional approaches to taphonomy exist, some of which rely almost exclusively on naturalistic data. One example is the work of Blumenschine (1987) at Serengeti and Ngorongoro, Kenya. This particular study was oriented toward the identification of the scavenger opportunities offered by modern environments. The research goal was to use them as analogs for the Plio-Pleistocene hominin landscapes. This study was criticized for two main reasons. First, it was observed that even the best modern analogs differ significantly from the habitats of the Plio-Pleistocene in the variety and distribution of carnivores and herbivores. Second, it was suggested that places like Serengeti cannot be considered as the best analog for that period in East Africa (Tappen 2001). Anyway, this is an extreme situation in which environments separated by c. two million years or more are compared. In spite of the tremendous differences imposed by this situation, regional naturalistic observations have proved important in the evaluation of many similar situations (Haynes 1982; Behrensmeyer 1983). This is particularly true when these observations are complemented with experimental taphonomic work (Dominguez-Rodrigo 2012). An understanding of the basic processes that govern the deposition and preservation of organic remains provides ways of separating those components of the fossil record that can be attributed to human activities.

Most of the approaches that try to identify regional taphonomic signals principally work with surface records, but there are conditions under which stratigraphic approaches can be used as well. One example is the work at Olorgesailie, Kenya, where the spatial distribution of at least two different time periods was examined and compared using regional taphonomic properties (Potts et al. 1999). In the ideal case, both surface and stratigraphic samples should be employed, and it is their comparative integration that proves to be more informative.

Future Directions

Regional taphonomy is a way to study and understand potential biases affecting archaeological assemblages. It is also a useful way to acquire paleoecological information and to select the most adequate places to answer specific research questions. Effectively, an understanding of the formation of palimpsests can be used to select places with better integrity or with the capacity to inform about particular activities, like scavenging or hunting. In turn, the knowledge about the aggregational history of the deposits can be used to study paleoclimatic and palaeoenvironmental issues (Bobe et al. 2007). For these reasons regional taphonomy is a research strategy that appears to be especially not only useful during the early phases of archaeological research but also capable of obtaining primary information. Most places in the world offer conditions for contamination of older bone assemblages with more recent bones. Regional taphonomy offers one way to respond effectively to that challenge.

Cross-References

Taphonomy in Bioarchaeology and Human Osteology

Taphonomy: Definition

Vertebrate Taphonomy in Archaeological Research