Miguel Ángel Maté-González

Micro-photogrammetric and morphometric differentiation of cut marks on bones using metal knives, quartzite, and flint flakes

In a previous article, we presented an innovative method to analyze cut marks produced with metal tools on animal bones from a metrical and tridimensional perspective (Maté-González et al. 2015). Such analysis developed a low-cost alternative technique to traditional microscopic methods for the tridimensional reconstruction of marks, using their measurements and sections. This article presents the results of an experimental study to test this photogrammetric and morphometric method for differentiating cut marks generated with metal, flint, and quartzite flakes. The results indicate statistically significant differences among cut marks produced by these three types of raw material. These results encourage the application of this method to archeological assemblages in order to establish a link between carcass processing and lithic reduction sequences on different raw materials and also to define the kind of tools used during butchery.

Assessment of statistical agreement of three techniques for the study of cut marks: 3D digital microscope, laser scanning confocal microscopy and micro-photogrammetry

In the last few years, the study of cut marks on bone surfaces has become fundamental for the interpretation of prehistoric butchery practices. Due to the difficulties in the correct identification of cut marks, many criteria for their description and classification have been suggested. Different techniques, such as three‐dimensional digital microscope (3D DM), laser scanning confocal microscopy (LSCM) and micro‐photogrammetry (M‐PG) have been recently applied to the study of cut marks. Although the 3D DM and LSCM microscopic techniques are the most commonly used for the 3D identification of cut marks, M‐PG has also proved to be very efficient and a low‐cost method. M‐PG is a noninvasive technique that allows the study of the cortical surface without any previous preparation of the samples, and that generates high‐resolution models. Despite the current application of microscopic and micro‐photogrammetric techniques to taphonomy, their reliability has never been tested. In this paper, we compare 3D DM, LSCM and M‐PG in order to assess their resolution and results. In this study, we analyse 26 experimental cut marks generated with a metal knife. The quantitative and qualitative information registered is analysed by means of standard multivariate statistics and geometric morphometrics to assess the similarities and differences obtained with the different methodologies.

3D analysis of cut marks using a new geometric morphometric methodological approach

The arrival of new methodological approaches to study microscopic qualities in cut mark morphology has been a major improvement in our understanding of butchering activities. Micro-morphological differences can be detected in multiple different taphonomic alterations on bone cortical surfaces that can later be used to compare different trace mark types. Through this, we can generate studies that are able to diagnose the specific taphonomic agents and activities that produce said traces that can be found on osteological surfaces. This paper presents experimental data that have been studied using micro-photogrammetry and geometric morphometrics, successfully distinguishing morphological differences in cut marks produced by different lithic tool types as well as different raw materials. The statistical results and methodologies presented here can later be applied to archaeological sites; aiding in our understanding of raw material exploitation, tool production as well as the different butchering activities that are present in faunal assemblages.

Differentiating percussion pits and carnivore tooth pits using 3D reconstructions and geometric morphometrics

During the end of the 20th century and the beginning of the 21st century the discussion on early human behavioral patterns revolved around the hunting versus scavenging debate. The correct identification of bone modifications, including percussion, cut and tooth marks, is a key issue within this debate. While many authors have shown that carnivore and human modifications can be easily distinguished, it is true that sometimes percussion marks without associated microstriations and tooth pits overlap morphologically, causing confusion, especially when unmodified hammerstones are used. In order to solve this equifinality problem, many investigations have focused their efforts on other pieces of evidence such as the identification of notches, fragmentation patterns and frequencies, among others. These studies, however, cannot be considered as fully conclusive. Within this paper we address the problem of equifinality when identifying percussion marks produced with unmodified hammerstones and tooth pits created by carnivores using new methodologies based on the 3D reconstruction of marks and their statistical multivariate analysis. For the purpose of this study a total of 128 marks– 39 percussion marks produced with an unmodified quartzite hammerstone, and 89 pits generated by different carnivores–were virtually modelled with the aid of a DAVID structured-light scanner SLS-2 and later analyzed by means of geometric morphometrics. Our results show that percussion marks not associated with striae fields and the pits generated by the carnivores studied here can be successfully distinguished.

Testing accuracy in 2D and 3D geometric morphometric methods for cut mark identification and classification

The analysis of bone surface modifications (BSMs) is a prominent part of paleoanthropological studies, namely taphonomic research. Behavioral interpretations of the fossil record hinge strongly upon correct assessment of BSMs. With the significant impact of microscopic analysis to the study of BSMs, multiple authors have discussed the reliability of these technological improvements for gaining resolution in BSM discrimination. While a certain optimism is present, some important questions are ignored and others overemphasized without appropriate empirical support. This specifically affects the study of cut marks. A diversity of geometric morphometric approaches applied to the study of cut marks have resulted in the coexistence (and competition) of different 2D and 3D methods. The present work builds upon the foundation of experiments presented by Maté-González et al. (2015), Courtenay et al. (2017) and Otárola-Castillo et al. (2018) to contrast for the first time 2D and 3D methods in their resolution of cut mark interpretation and classification. The results presented here show that both approaches are equally valid and that the use of sophisticated 3D methods do not contribute to an improvement in accuracy.

A new high-resolution 3-D quantitative method for analysing small morphological features: an example using a Cambrian trilobite

Taphonomic processes play an important role in the preservation of small morphological features such as granulation or pits. However, the assessment of these features may face the issue of the small size of the specimens and, sometimes, the destructiveness of these analyses, which makes impossible carrying them out in singular specimen, such as holotypes or lectotypes. This paper takes a new approach to analysing small-morphological features, by using an optical surface roughness (OSR) meter to create a high-resolution three-dimensional digital-elevation model (DEM). This non-destructive technique allows analysing quantitatively the DEM using geometric morphometric methods (GMM). We created a number of DEMs from three populations putatively belonging to the same species of trilobite (Oryctocephalus indicus) that present the same cranidial outline, but differ in the presence or absence of the second and third transglabellar furrows. Profile analysis of the DEMs demonstrate that all three populations show similar preservation variation in the glabellar furrows and lobes. The GMM shows that all populations exhibit the same range of variation. Differences in preservation are a consequence of different degrees of cementation and rates of dissolution. Fast cementation enhances the preservation of glabellar furrows and lobes, while fast dissolution hampers preservation of the same structures.