Abstract
Fragmentation is a recurring feature of archaeological faunal material, and impacts many aspects of zooarchaeological studies from taxonomical identification to biometric studies. It can result from anthropic and natural actions that occurred respectively before and/or after bone deposit. While several bone fragmentation typologies have been described, they are currently based on both macroscopic observations and researcher subjectivity and lack the universality necessary for inter-study comparisons. To fulfill this need we present a standardized landmark-based protocol for the description and quantification of mandibular fragmentation patterns, using two insular rodents of different sizes as models. The rice rats (Oryzomyini tribe) and the agouti (Dasyprocta) from the Lesser Antilles were abundant during the pre-Columbian Ceramic Age (500 BCE-1500 CE). Their mandibles’ shapes were quantified using the coordinates of 13 2D-landmarks. We show that landmark-based measurements can be used to:—assess the preservation differences between taxa of the same taxonomic group (e.g., rodents),—estimate the level of preservation of a skeletal part (e.g., mandible),—describe fragmentation patterns without pre-existing typologies and—facilitate the application of geometric morphometric methods to fragmented archaeological material. Our novel approach, leveraging fragmentation analyses and establishing specific fragmentation patterns, frees itself from existing typologies and could be systematically applied to future research.
Highlights
IntroductionArchaeological bones are studied to investigate the relationships between past human societies and animals as well as the environment
Bone fragmentation results from preand/or post-depositional taphonomic processes that may be caused by natural or anthropogenic actions [1,2]: butchering and hammering of bones, trampling, climato-edaphic effects, non-human biological agents, and breakage resulting from excavation, transportation, and storage [3]
The coronoid process is higher than the condyloid process, while it is smaller for the agouti
Summary
Archaeological bones are studied to investigate the relationships between past human societies and animals as well as the environment. Mandibles of large [14] and small mammals [15] tend to be well preserved in archaeological deposits as a result of their high structural density. The bone density differs between the taxa and the bone mineral composition varies according to the age of the animal, which induces different structural and mechanical properties [16]. Within the same group of taxa, e.g., rodents, mandibles do not always have the same mechanical properties [15]. Despite these observations, mandibles tend to show a non-random fragmentation and can be divided into two parts: the anterior part or corpus which bears the teeth, and the posterior part or ramus that is attached to the skull. The ability to identify to which species or group of species belongs a mandibular fragment depends on its size and the anatomical part represented [18,19]
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