Dynamic modification of cut marks by trampling: temporal assessment through the use of mixed-effect regressions and deep
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(2020) 12:4
ORIGINAL PAPER
Dynamic modification of cut marks by trampling: temporal assessment through the use of mixed-effect regressions and deep learning methods Marcos Pizarro-Monzo 1 & Manuel Domínguez-Rodrigo 1 Received: 21 June 2019 / Accepted: 28 November 2019 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Cut marks exposed to a short period of trampling were easily differentiated from trampling marks. Here, through the combined use of cross-validated logistic regression, mixed-effect regression models and computer vision deep learning methods, we approach the timing and modification rate of the microscopic variables that characterize cut marks. This study emphasizes the need to understand that bone surface modifications are dynamic taphonomic entities subjected to context-dependent morphing processes. Every depiction of a mark is just time-determined. Here, we show through experiments that trampling affected mostly the presence and internal configuration of microstriations, as well as the flaking and the morphology of the shoulder of the mark. The presence of overlapping striae and microabrasion were reported as signatures of trampling which did not affect cut mark morphology. Sandy sediment was found more abrasive than gravel sediment because of its potential to get inside the grooves of marks and modify their walls more intensively. The moderate abrasion process modeled here did not impact cut marks to the point of not being differentiated from other types of marks. A comparison with trampling marks successfully classified both types of modifications. Keywords Taphonomy . Cut marks . Trampling . Logistic regression . Mixed-effect regression . Deep learning
Introduction Representations of cut marks as experimentally modeled provide a characterization of these bone surface modifications (BSM) that may be realistically applied to the fossil paleoanthropological record only in contexts of pristine preservation. Several authors have emphasized that such static modeling does not reproduce the range of morphing that BSM undergo under the effect of biostratinomic and diagenetic processes (e.g., Gaudzinski-Windheuser et al., 2010; Pineda et al., 2019; Rabinovich et al., 2012). Indeed, BSM should only be understood under conceptual frameworks that emphasize the dynamic nature of taphonomic entities. Experiments Electronic supplementary material The online version of this article (https://doi.org/10.1007/s12520-019-00966-6) contains supplementary material, which is available to authorized users. * Manuel Domínguez-Rodrigo [email protected] 1
IDEA (Institute of Evolution in Africa), University of Alcalá, Covarrubias 36, 28010 Madrid, Spain
simulating natural abrasion by sediment and water show that shallow BSM marks frequently disappear and others penetrating deeper into the cortical layers can either disappear or show a variable degree of morphing (Gaudzinski-Windheuser et al., 2010; Pineda et al., 2019; Rabinovich et al., 2012). Similar effects are documented when BSM are e
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