Geometric Morphometrics

Fossil remains of small mammals of the Leporidae family (genus Oryctolagus and Lepus) are abundant in numerous paleontological and archaeological deposits from the Quaternary. Many species are endemic to Western Europe, which makes them reliable markers of change in the ecosystems in which prehistoric human societies evolved. Paradoxically, morphological variability of leporids is still poorly understood and current phylogeny remains a subject of debate. This work focuses on the morphometric diversity of rabbits (Oryctolagus) and hares (Lepus) over nearly two million years of evolution. We applied osteometry and geometric morphometric (2D and 3D) analyzes to bone and dental remains of current populations and 73 fossil samples from perimediterranean regions (Spain, France, Italy, Portugal) during different moments of the Pleistocene. These data provide insights concerning Leporidae adaptations to environmental change as well as more general evolutionary trends. Here we propose a new phylogeny for the genus Oryctolagus and present different dispersion phases for Western Europe. Several population expansion events coupled with the recolonization of refuge areas and local extinctions are highlighted in response to global climate change. These results allow us to discuss the presence of these small game species in the environment and contribute to the debate concerning relations between leporids and human communities. Humans have regularly consumed leporids since at least the Middle Paleolithic. Their significant increase in the diet at the end of the Upper Paleolithic, however, cannot be explained solely by cognitive, cultural or economic changes but rather coincides with biogeographic variations of these species.

Diagenetic distortion can be a major obstacle to collecting quantitative shape data on paleontological specimens, especially for three-dimensional geometric morphometric analysis. Here we utilize the recently-published algorithmic symmetrization method of fossil reconstruction and compare it to the more traditional reflection & averaging approach. In order to have an objective test of this method, five casts of a female cranium of Papio hamadryas kindae were manually deformed while the plaster hardened. These were subsequently "retrodeformed" using both algorithmic symmetrization and reflection & averaging and then compared to the original, undeformed specimen. We found that in all cases, algorithmic retrodeformation improved the shape of the deformed cranium and in four out of five cases, the algorithmically symmetrized crania were more similar in shape to the original crania than the reflected & averaged reconstructions. In three out of five cases, the difference between the algorithmically symmetrized crania and the original cranium could be contained within the magnitude of variation among individuals in a single subspecies of Papio. Instances of asymmetric distortion, such as breakage on one side, or bending in the axis of symmetry, were well handled, whereas symmetrical distortion remained uncorrected. This technique was further tested on a naturally deformed and fossilized cranium of Paradolichopithecus arvernensis. Results, based on a principal components analysis and Procrustes distances, showed that the algorithmically symmetrized Paradolichopithecus cranium was more similar to other, less-deformed crania from the same species than was the original. These results illustrate the efficacy of this method of retrodeformation by algorithmic symmetrization for the correction of asymmetrical distortion in fossils. Symmetrical distortion remains a problem for all currently developed methods of retrodeformation.

In the Late Archaic - Early Classic period, the Attic ceramic industry was characterized by a kind of duality. On the one hand, the red-figure technique was flourishing, when Euphronios’, Douris’ or the Berlin Painter’s works represented the height of Greek vase painting. On the other hand, the market was also covered by large quantities of low-quality black-figure pottery. Not only in Athens, but even in the whole Ancient Mediterranean these mass-produced vessels emerge constantly, even from modern excavations. Therefore, in contrast to most vases of more talented painters they can be attached to an archaeological feature or layer. Due to their inadequate style, relatively few characteristics can be determined while looking at the painting. Thus, the manufacturing criteria, such as the details of the shapes, are more important in the attribution. In this paper, I study the late black-figure lekythoi of the Museum of Fine Arts in Budapest with the help of geometric morphometrics using 3D reconstructions.

In this paper we present a three-dimensional (3D) morphometrical assessment of human tibia sexual dimorphism based on whole bone digital representation. To detect shape-size and shape differences between sexes, we used geometric morphometric tools and colour-coded surface deviation maps. The surface-based methodology enabled analysis of sexually dimorphic features throughout the shaft and articular ends of the tibia. The overall study dataset consisted of 183 3D models of adult tibiae from three Czech population subsets, dating to the early medieval (9-10 th century) (N = 65), early 20 th century (N = 61) and 21 st-century (N = 57). The time gap between the chronologically most distant and contemporary datasets was more than 1200 years. The results showed that, in all three datasets, sexual dimorphism was pronounced. There were some sex-dimorphic characteristics common to all three samples, such as tuberosity protrusion, anteriorly bowed shaft and relatively larger articular ends in males. Diachronic comparisons also revealed substantial shape variation related to the most dimorphic area. Male/female distinctions showed a consistent temporal trend regarding the location of dimorphic areas (shifting distally with time), while the maximal deviation between male and female digitized surfaces fluctuated and reached the lowest level in the 21 st-century sample. Sex determination on a whole-surface basis yielded the lowest return of correct sex assignment in the 20 th-century group, which represented the lowest socioeconomic status. The temporal variation could be attributed to changes in living conditions, the decreasing lower limb loading/labour division in the last 12 centuries having the greatest effect. Overall, the results showed that a surface-based approach is successful for analysing complex long bone geometry.

Several lines of bioarchaeological research have confirmed the gradual decline in lower limb loading among past human populations, beginning with the transition to agriculture. The goal of this study was to assess whether human tibial curvature reflects this decline, with a special emphasis on the time-span during which the pace of technological change has been the most rapid. Our study is the first (1) to apply longitudinal curvature analysis in the antero-posterior (A-P) and medio-lateral (M-L) planes to the human tibia, and (2) that incorporates a broad temporal population sample including the periods of intensification of agriculture, urbanization and industrialization (from 2900 BC to the 21 st century AD; N = 435) within Czech territories. Using three-dimensional geometric morphometrics, we investigated whether anterior tibial curvature mirrors assumed diminishing lower limb loading between prehistoric and industrialized societies and explored its shape in all three dimensions. Results showed the continuous trend of A-P straightening of the shaft. This straightening was associated with a relative sigmoidal curve accentuation in the M-L plane. Given the timescale involved and the known phenomenon of declining mobility, such adaptive changes in bone geometry can be interpreted in terms of the diminishing biomechanical demands on the tibia under different living conditions.

That great ape endocranial shape development persists into adolescence indicates that the splanchnocranium succeeds brain growth in driving endocranial development. However, the extent of this splanchnocranial influence is unknown. We applied two-block partial least squares analyses of Procrustes shape variables on an ontogenetic series of great ape cra-nia to explore the covariation of the endocranium (the internal braincase) and splanchnocra-nium (face, or viscerocranium). We hypothesized that a transition between brain growth and splanchnocranial development in the establishment of final endocranial form would be manifest as a change in the pattern of shape covariation between early and adolescent ontogeny. Our results revealed a strong pattern of covariation between endocranium and splanchno-cranium, indicating that chimpanzees, gorillas, and orangutans share a common tempo and mode of morphological integration from the eruption of the deciduous dentition onwards to adulthood: a reflection of elongating endocranial shape and continuing splanchnocranial prognathism. Within this overarching pattern, we noted that species variation exists in magnitude and direction, and that the covariation between the splanchnocranium and endocra-nium is somewhat weaker in early infancy compared to successive age groups. When correcting our covariation analyses for allometry, we found that an ontogenetic signal remains, signifying that allometric variation alone is insufficient to account for all endocra-nial-splanchnocranial developmental integration. Finally, we assessed the influence of the cranial base, which acts as the interface between the face and endocranium, on the shape of the vault using thin-plate spline warping. We found that not all splanchnocranial shape changes during development are tightly integrated with endocranial shape. This suggests that while the developmental expansion of the brain is the main driver of endocranial shape during early ontogeny, endocranial development from infancy onwards is moulded by the splanchnocranium in conjunction with the neurocranium.

Landmarks are the hallmark of biological shape analysis as discrete anatomical points of correspondence. Various systems have been developed for their classification. In the most widely used system, developed by Bookstein in the 1990s, landmarks are divided into three distinct types based on their anatomical locations and biological significance. As Bookstein and others have argued that different landmark types possess different qualities, e.g., that Type 3 landmarks contain deficient information about shape variation and are less reliably measured, researchers began using landmark types as justification for selecting or avoiding particular landmarks for measurement or analysis. Here, we demonstrate considerable variation in landmark classifications among 17 studies using geometric morphometrics (GM), due to disagreement in the application of both Bookstein's landmark typology and individual landmark definitions. A review of the literature furthermore shows little correlation between landmark type and measurement reproducibility, especially when factors such as differences in measurement tools (calipers, digitizer, or computer software) and data sources (dry crania, 3D models, or 2D images) are considered. Although landmark typology is valuable when teaching biological shape analysis, we find that employing it in research design introduces confusion without providing useful information. Instead, researchers should choose landmark configurations based on their ability to test specific research hypotheses, and research papers should include justifications of landmark choices along with landmark definitions, details on landmark collection methods, and appropriate interobserver and intraobserver analyses. Hence, while the landmarks themselves are crucial for GM, we argue that their typology is of little use in applied studies.

La grotte de l’Observatoire constitue un site d’intérêt pour les études portant sur l’occupation du territoire au début du Paléolithique supérieur du fait de sa localisation géographique et des vestiges archéologiques qu’elle a livrés. Mis au jour au début du XXème siècle, l’assemblage de pointes de projectile aurignaciennes en matière osseuse de ce site est le plus important en nombre pour les gisements localisés sur le pourtour méditerranéen. Il comprend onze pointes à base fendue et une pointe à base massive. L’application des principes de la morphométrie géométrique à l’étude de ces armatures de chasse permet d’aborder la distribution des règles de production régissant leur manufacture. Quatre conceptions volumétriques sont identifiées pour les pointes à base fendue et mises en relation avec des spécimens similaires provenant de contextes archéologiques espagnols, français, italiens, allemands et hongrois. La pointe à base massive, quant à elle, présente des similitudes avec des armatures mises au jour en Dordogne, en Charente et dans la vallée de la Meuse. / Owing to its geographic location and to the nature of the archaeological remains it yielded, the Grotte de l’Observatoire constitutes a key site for studies focussing on land occupation at the beginning of the Early Upper Palaeolithic. Unearthed at the beginning of the XXth century, the osseous projectile points assemblage from this site is the largest in the Mediterranean region. It accounts for eleven split-based points and one massive-based point. The application of geometric morphometrics principles to their study highlights the distribution of the rules of production that guided their manufacture. Four volumetric templates are identified for the split-based points and are related to specimens from Spanish, French, Italian, German, and Hungarian archaeological contexts. For the case of the massive-based point, it bears similarities with some implements found in sites located in Dordogne, Charente, and Belgium.

The manufacture of composite projectile technology requires the production and assemblage of tightly fitted parts designed to fulfill a number of distinct functions. Each part combines a number of techno-functional units, and various processes may be responsible for the shape variability of these units. In order to investigate the relative contribution of each process to the overall variability of a projectile implement, one must identify the point of demarcation between its techno-functional units. In the present paper, the concept of shape modularity is introduced to precisely identify this locus. The application of geometric morphometrics and shape modularity to the study of two Aurignacian osseous projectile point types, i.e., split- and massive-based points, reveals interesting patterns. On both types, the maximum width delimits the distal and proximal techno-functional units of these objects. When focusing on the morphometric variability and the geographic distribution of the implements' proximal unit, the eight shapes identified for split-based points are found over vast regions of Europe. On the other hand, the two proximal shapes defined for massive-based points show a pattern of local, or regional, aggregation. These proximal shapes were likely considered fit for hafting and hunting by the prehistoric populations who reproduced them, and they are interpreted as a proxy for the socially shared rules of production that guided the manufacture of these tool types. They could therefore be used in future studies that aim to identify group membership amongst the Aurignacian metapopulation and the extent of their interactions.

Studies of bone surface modifications (BSMs) such as cut marks are crucial to our understanding of human and earlier hominin subsistence behavior. Over the last several decades, however, BSM identification has remained contentious, particularly in terms of identifying the earliest instances of hominin butchery; there has been a lack of consensus over how to identify or differentiate marks made by human and non-human actors and varying effectors. Most investigations have relied on morphology to identify butchery marks and their patterning. This includes cut marks, one of the most significant human marks. Attempts to discriminate cut marks from other types of marks have employed a variety of techniques, ranging from subjectively characterizing cut mark morphology using the naked eye, to using high-powered microscopy such as scanning electron microscopy (SEM) or micro-photogrammetry. More recent approaches use 3D datasets to obtain even more detailed information about mark attributes, and apply those to the fossil record. Although 3D datasets open promising new avenues for investigation, analyses of these datasets have not yet taken advantage of the full 3D surface morphology of BSM. Rather, selected cross-sectional slices of 3D scans have been used as proxies for overall shape. Here we demonstrate that 3D geometric morphometrics (GM), under the " Procrustes paradigm " and coupled with a Bayesian approach, probabilistically discriminates between marks caused by different butchery behaviors. At the same time, this approach provides a complete set of 3D morphological measurements and descriptions. Our results strengthen statistical confidence in cut mark identification and offer a novel approach that can be used to discriminate subtle differences between cut mark types in the fossil record. Furthermore, this study provides an incipient digital library with which to make future quantitative comparisons to archaeological examples, including contentious specimens that are key to understanding the earliest hominin butchery.