3D Microscopy

In this work we tested the application of 3D microscopy
to technological analysis of artistic engravings on Palaeolithic
mobiliary art objects. The aim of this research is
to understand the technical and artistic procedures followed
by prehistoric artists. Here we analysed an unpublished
right mandible of Bos primigenius (auroch), coming
from the portable art assemblage of Paglicci Cave (Foggia,
Southern Italy). This site shows an artistic production
of exceptional importance that offers an essential record
about Paleolithic mobiliary art in Italy (from Gravettian to
Final Epigravettian). The studied mandible, coming from
Evolved Epigravettian layers, displays an engraved motif
of difficult interpretation. Before studying the archaeological piece we produced
an experimental programme in order to compare archaeological
data with those obtained through replication
under controlled parameters. We produced a set of
experimental engravings on bone using burins and not
retouched blanks. The experimental and archaeological
engravings were analysed by means of a Hirox 3D Digital
Microscope KH-7700.Cross sections from the median
part of each groove have been observed and metrical
parameters have been collected (depth, breadth at the
floor and breadth at the top of the groove). In order to
describe the shape of each cross section the ratio between
the breadth at the top and the breadth at the
floor, as well as the ratio between the breath at the top
and the depth of cut marks have been calculated.
Results of the analysis revealed that the overall contours
of the figure was engraved first, while engraved lines
inside were added afterwards. The experimental data
pointed out that the morphometric analysis reveal no
discriminating characters between the engravings produced
by burins and those produced by not retouched
blanks; on the other hand the micromorphological analysis
showed a clearer context, where we can characterize
the engravings produced by the two kinds of tool. The
analysis of archaeological piece revealed a high homogeneity
of the micromorphological and micromorphometrical
data, feature which suggests the use of a single tool in the realization of the figure, probably a burin. In
addition to it the morphometric data collected on the
mobilary art object were compared with those collected
on a sample of cut marks from the same site. Significant
differences were found between the two samples: in particular the cut marks cross-sections are V-shaped, whilst
the art object is characterised by U-shaped engravings.
As regards the micro-morphological data, this research
seems to give good indications for the detection of parameters
that allow us to recognize the kinds of tool used
for engraving. The application of 3D microscopy reveals
new perspectives for the identification of techniques
and gesture of prehistoric artists. Finally, the differences
found between the art object and the cut marks are of
great interest for developing protocols able to separate
between butchering marks and engravings of dubious
origin.

Digital imaging allows to collect and process morphometric quantitative data on archaeological finds. The Research Unit of Prehistory and Anthropology of the University of Siena is currently developing new protocols for the analysis of bone modifications using a Hirox Digital Microscope KH-7700. This instrument captures 3D images of the observed surfaces enabling the direct observation of butchering marks, artistic engravings and non-anthropic evidences (for instance tooth marks) from several points of view; it also allows a rapid procurement of several quantitative data (linear and angular measurements) that can be processed through univariate and multivariate statistics. After the analysis of more than four hundred specimens, we are presenting in this paper the results of several case-studies from Italian Palaeolithic and Metal Age sites: we demonstrated that processing quantitative data it is possible to separate between butchering marks inflicted using stone and metal tools; to identify the kind of stone tool used to produce prehistoric artistic engravings; to separate between butchering marks and artistic engravings. All data coming from the analysis of archaeological specimens are compared with those obtained carrying out experimental proofs; it allows to corroborate our results. The encouraging obtained outcome confirms the validity of our protocols and the important role that computer applications and quantitative methods play for understanding prehistory.

Digital microscopic analysis is here applied to the study of marks produced on bones by different stone tools. Two unretouched flint flakes and two burins have been used to inflict cut marks on fresh, boiled and dry bone. Five striations have been produced for three times on each mate rial with each tool. First time single cut marks have been inflicted; second time each groove has been inflicted moving the hand two times in the same direction; third time each groove has been inflicted using the tool like a saw, moving the hand bidirectionally. Cross sections from the median part of each groove have been analysed using an Hirox 3D digital microscope (KH-7700) and metrical parameters have been collected (depth, breadth at the floor and breadth at the top of the groove). In order to describe the shape of each cross section the ratio between the breadth at the top and the breadth at the floor, as well as the ratio between the breath at the top and the depth of cut marks have been calculated. Preliminary results show that tool wear, bone conditions and the way in which cut marks were inflicted influence grooves shape. Large variability of the recorded parameters doesn't allow to discriminate between different stone tools and different actions.

This study uses a combination of digital microscopic analysis and experimental archaeology to assess stone tool cut marks on animal bones. We used two un-retouched flint flakes and two burins to inflict cut marks on fresh, boiled, and dry ungulate bones. The experiment produced three series of three engravings on each bone with each of the experimental tools. The first series involved one single stroke; the second, two strokes in the same direction; and the third, multiple strokes using a to-and-fro movement. We analyzed the striations using a Hirox 3D digital microscope (KH-7700) and collected metric and profile data on the morphology of the cut marks. In order to describe the shape of each cross section, we calculated the ratio between the breadth at the top and the breadth at the floor of cut marks. Preliminary results show that both the tool type and the method of creating the cut mark influence the shape of the resulting groove. In our experiment, morphological parameters can be used to differentiate between marks produced using un-retouched flint flakes and those produced using burins. However, neither morphological nor morphometric analysis allows us to identify the mechanical motion used to produce the cuts, nor the state of the bone (fresh, boiled, or dry) at the moment of marking.