Comparison of coordinate measurement precision of different landmark types on human crania using a 3D laser scanner and a 3D digitiser: Implications for applications of digital morphometrics

A total of 11 340 Cartesian coordinates of 42 homologous landmarks on five excavated human crania were recorded by three observers using a three‐dimensional (3D) digitiser and computer models created with a 3D laser scanner. The aim was to compare the errors of the coordinate data of landmarks of different types recorded with these two techniques. The results showed that digitiser‐based and 3D model‐based coordinate measurements had overall standard deviations of, respectively, ±0.79 and ±1.05 mm. However, the 3D digitiser yielded the most precise coordinate data for landmarks defined primarily by biological criteria (Type I landmarks), while the 3D laser scanner models yielded the most precise coordinate data for landmarks defined primarily by geometric criteria (Type III landmarks). These findings are likely to influence the research design of future craniometric studies, as they indicate that the suitability of certain landmark types as reference points for geometric operations, such as partial Procrustes analysis, depends on the method by which they are measured. This information is particularly important for retrospective research or for combined databases such as FORDISC or CRANID, which may integrate different types of landmarks recorded by different researchers and/or instruments. Crania displaying poor preservation and surface discoloration yielded larger measurement errors, especially for the 3D model measurements. This is not surprising given that landmarks on 3D models cannot be located using tactile means, but have to be located solely on a visual basis. Nonetheless, even though the digitiser measurements exhibit an overall precision slightly greater than the 3D model measurements, both techniques yield coordinate data with a precision sufficient for most craniometric research. Copyright © 2010 John Wiley & Sons, Ltd.     

A 3D morphometric analysis of surface geometry in Levallois cores: patterns of stability and variability across regions and their implications

Levallois cores and products were manufactured by hominin populations distributed across wide regions of Africa and Eurasia. Levallois technology remains an important focus for research in Palaeolithic archaeology, yet quantitative morphological comparisons of Levallois core morphology from different regions remain rare. Here, utilizing Levallois cores from Africa, the Near East, Europe, and the Indian subcontinent, patterns of morphological variability in the shape of the Levallois flaking surface and core outline (margin) shape were examined for patterns of variability and stability across regions using 3D geometric morphometrics. The multivariate statistical shape analyses undertaken revealed a clear pattern: that is, the greatest levels of shape variability in Levallois cores is evident in the form of their outline (planform) shape. Conversely, the geometrical relationship between the margin of the Levallois cores and their topological surface morphology was relatively uniform. This pattern of variability was evident in terms of variation both across regions and between cores from the same locality. These results indicate that the outline form of such cores was a less important variable than the geometric/topological properties of the surface morphology and, in particular, the relationship between the margin of the core and those variables. These results have implications for why it has been reported that replicating such cores in modern experiments is a particularly difficult task. The specific interrelationship between the geometric properties of the core and the core margin provide further evidence that Levallois core technology would be unlikely to emerge from the context of opportunistic migrating platform reduction strategies (such as those seen in many Mode 1 industries). If, as is widely suggested, Levallois cores were deliberate products in Pleistocene contexts, these results also hint that relatively sophisticated means of social transmission (i.e. teaching) may have been required to sustain their production over time and space.     

The northern fluted point complex: technological and morphological evidence of adaptation and risk in the late Pleistocene-early Holocene Arctic

Analyses of fluted point technology and Paleoindian technological risk have contributed to our understanding of human adaptation across North America in the late Pleistocene and early Holocene. However, poor chronological control has dissuaded similar studies of fluted points found in Alaska and northern Yukon and our understanding of their adaptive role in early arctic adaptations remains unclear. Two new archeological sites have provided reliable radiocarbon data and for the first time, a comprehensive analysis of northern fluted points is possible. Here, technological and morphological analyses of northern fluted points are presented, including variables statistically evaluated and compared to a collection of fluted Folsom artifacts serving as a reference. Variation in tool shape was measured using geometric morphometrics, and a new approach to landmark placement designed to characterize basal morphology and allow the analysis to include tool fragments is presented. Results confirm that northern fluted points represent a cohesive technological strategy and are used to formulate hypotheses suggesting its service as a risk-management system promoting ease-of-replacement-after-failure to offset transport costs and reduce risk during long-distance travel.     

Evaluation of Structure from Motion Software to Create 3D Models of Late Nineteenth Century Great Lakes Shipwrecks Using Archived Diver-Acquired Video Surveys

Here we demonstrate the ability to use archived video surveys to create photorealistic 3D models of submerged archeological sites. We created 3D models of two nineteenth century Great Lakes shipwrecks using diver-acquired video surveys and Structure from Motion (SfM) software. Models were georeferenced using archived hand survey data. Comparison of hand survey measurements and digital measurements made using the models demonstrate that spatial analysis produces results with reasonable accuracy when wreck maps are available. Error associated with digital measurements displayed an inverse relationship to object size. Measurement error ranged from a maximum of 18 % (on 0.37 m object) and a minimum of 0.56 % (on a 4.21 m object). Our results demonstrate SfM can generate models of large maritime archaeological sites that for research, education and outreach purposes. Where site maps are available, these 3D models can be georeferenced to allow additional spatial analysis long after on-site data collection.     

Accuracy evaluation of the semi-automatic 3D modeling for historical building information models

It is stated that 3D recording and modeling of heritage buildings entail accurate building models (as-built). However, this paper presents an analysis of the 3D modeling accuracy for the creation of historical building information models (HBIM), considering the complexity and the deformations of historical buildings, using point cloud data and BIM tools. The 3D modeling processes analyzed are based on a three-stage semi-automatic approach leading to the generation of HBIM, including manual and automatic processes. The three stages consist of: (a) optical and terrestrial laser scanning; (b) meshing processes; and finally (c) 3D solid modeling to be assembled into HBIM. Next, this approach analyzed the mesh deformations generated automatically in comparison to the initial point cloud data. The deformations and the accuracy evaluation have been undertaken using different commercial software. Finally, our modeling approach shows that it can improve the accuracy of the 3D models achieved using existing BIM technologies.     

A crossbeam co-ordinate caliper for the morphometric analysis of lithic nuclei: a description,test and empirical examples of application

Over the last four decades, there has been surprisingly little advance in the quantitative morphometric analysis of Palaeolithic stone tools, especially compared to that which has taken place in biological morphometrics over a comparable time frame. In Palaeolithic archaeology's sister discipline of palaeoanthropology, detailed quantitative morphometric, geometric morphometric, and even 3D geometric morphometric analyses are now seen almost as routine. This period of relative methodological stasis may have been influenced by the lack of homologous landmarks on many lithic tools (essential for any comparative analysis), especially core-based technologies of the Lower Palaeolithic. Archaeological field conditions may also prohibit the use of expensive and delicate precision instruments in certain cases. Here we present a crossbeam co-ordinate caliper that – crucially – both geometrically locates and measures distances between morphologically homologous landmarks upon lithic nuclei via a single protocol. Intra- and inter-observer error tests provide evidence that error levels associated with the instrument fall within acceptable ranges. In addition, we present empirical examples of application in the form of a multivariate analysis of 55 discrete morphometric variables, and a 3D geometric morphometric analysis of co-ordinate landmark configurations derived from Pleistocene lithic nuclei (i.e. ‘cores’ sensu lato). We also introduce to lithic studies some techniques for the study of shape variation that have previously been used with success in biological morphometric analyses. We conclude that use of an instrument such as the crossbeam co-ordinate caliper may provide a useful adjunct to traditional techniques of lithic analysis, particularly in developing a quantitative morphometric approach.     

Discriminating Paleoindian point types from Florida using landmark geometric morphometrics

Traditional artifact typologies are typically poorly defined. While several attributes usually help define a “type,” shape is invariably the most important. Here I report on a study that uses landmark-based geometric morphometrics to better define three Paleoindian point types from Florida: Suwannees, Simpsons, and Transitional Side Notched. Bilaterally symmetric specimens were created from the original artifacts to capture the presumed ideational forms of the points. The shapes of the bases and the entire points were tested to determine whether the types could be discriminated, and if so which shape was best at discriminating the types. The results show that the base configurations were best at discriminating the groups in two different jackknife allocation tests. The entire point shape was less robust due to the variability in blade shape. The study demonstrates that the three point types can be rigorously defined in ways that are usable in daily archaeological practice, and that base shape, rather than the entire shape, is a better discriminator. Further, the study demonstrates the utility of using several freeware programs for processing and analyzing shape data.     

Evaluating morphological variability in lithic assemblages using 3D models of stone artifacts

Technological and morphological variability in lithic artifacts is commonly used to identify taxonomic entities in Paleolithic research contexts. Assemblages are mainly studied using either linear distance measurements or qualitative assessments of morphologies. Here, we present a method to quantify morphological variability in lithic artifacts using 3D models of stone artifacts. Our study on the sequence of the Upper Paleolithic layers V–I from the site Yabroud II in western Syria, demonstrates that utilizing 3D models provides a new insight into the variability of lithic technologies. We use quantitative data on convexities, twist and scar patterns on cores and blades, attributes previously not readily quantifiable, to trace technological change through the archaeological sequence. We are able to identify differences and translate these findings into a grouping of the layers. While layers VI–II are characterized by technological continuity and were grouped together, layers V and I can be separated from this group and represent technologically different groups chronologically before and after. Our results demonstrate the potential of 3D models for studying morphological variability in lithic assemblages.     

Micro‐CT Imaging and Analysis of Enamel Defects on the Early Late Pleistocene Xujiayao Juvenile

Dental pathologies and enamel defects in East Asian hominins have rarely been reported. Here, we systematically document and describe a suite of enamel defects in the Xujiayao juvenile maxilla, an East Asian hominin from the early Late Pleistocene that may represent an unknown hominin lineage. In addition, we determine the chronology of growth disruptions represented by matched linear enamel hypoplasias, evaluate the long‐held hypothesis that the large brownish pit on the I¹ is evidence of dental fluorosis and assess the utility of micro‐computed tomography (micro‐CT) techniques in analyzing enamel defects. With the use of binocular microscopy, scanning electron microscopy (SEM) and micro‐CT imaging techniques, the Xujiayao teeth were found to exhibit a high number of pit‐form defects seldom seen in the fossil record. By matching the timing of linear enamel hyperplasia across multiple teeth, a minimum of five developmental disruptions were identified, indicating that the Xujiayao juvenile experienced several growth disturbances during its short lifespan. Our SEM and micro‐CT analyses suggest that the large pit on the I¹ is an enamel hypoplasia due to its morphology and pre‐eruptive enamel thinning. It is not a post‐eruptive fluorotic pit, and there is no evidence of chalkiness or opacity associated with dental fluorosis. The micro‐CT technique made it possible to verify the presence of enamel hypoplasia and to more precisely quantify defect dimensions, especially in unerupted teeth and shallow hypoplasias that are difficult to detect by binocular microscopy or SEM. Copyright © 2015 John Wiley & Sons, Ltd.     

A Test of the Effectiveness of the Coimbra Method in Capturing Activity‐induced Entheseal Changes

The current paper tests the effectiveness of entheseal changes in expressing activity patterns when the former have been recorded using the new Coimbra method. Changes on the subscapularis and biceps brachii were recorded using the Coimbra method on 78 men from the documented Athens Collection. Generalised linear models were adopted with entheseal changes as dependent variable and cross‐sectional geometric properties, age and body mass as predictors. The results suggest that age is the factor most frequently affecting entheseal changes; however, its impact is not as systematic as found in previous studies. Body mass is rarely statistically significant, again contradicting earlier studies. Finally, activity proxied by cross‐sectional geometric properties is occasionally significant, but no clear pattern emerges that can associate specific entheseal morphological changes with specific directions of mechanical loading. Copyright © 2016 John Wiley & Sons, Ltd.     

Quantifying Ship Shape in Archaeology: Evaluating 3D Geometric Morphometrics

The analysis of the archaeological remains of ships and boats, in particular hull shapes, have been central to wider analysis of performance, function, and significance within past societies. This article reviews established methods of quantifying shape in ship and boat archaeology—linear measurement ratios and form coefficients—and evaluates the utility of 3D geometric morphometrics (GM). The 3D shape of 30 vessels from north‐west Europe dating between 325 BC and AD 1915 are quantified to study how hull shape relates to a vessel's function and intended operating environment. A comparison of the three methods highlights the importance of analysing the complexity of a hull in a holistic manner and demonstrates that 3D GM outperforms the traditional methods.     

Can morphospace shed light on cave bear spatial-temporal variation? Population dynamics of Ursus spelaeus from Romualdova pe?ina and Vindija, (Croatia)

Cave bear (Ursus spelaeus) behavioural ecology, as evidenced through population dynamics, is crucial for improving our understanding of why this species went extinct. Despite the fact that the bones of this species have been recovered in very large quantities, allowing for extensive study, fundamental questions regarding its life-ways remain unanswered. We present research using geometric morphometrics (GMM) on molars to investigate population structure based on morphological variation over space and through time. This preliminary work deliberately restricts the geographic catchment area for sampling, allowing for a meaningful appraisal of scale of variation within a spatially conservative framework. Our results demonstrate no significant morphological variation evident temporally and a small but statistically significant degree of shape variation geographically despite the proximity of the study localities. These findings suggest that an accurate quantitative exploration of morphospace may be an important source of evidence on environmental and climatic shifts and the resulting influence on animal morphology.     

The Post‐Mortem Pressure Distortion of Human Crania Uncovered in an Early Medieval Pohansko (Czech Republic) Graveyard

Post‐mortem distortion resulting from the pressure of overlying sediments (i.e. grave backfill) is one of the taphonomic factors capable of altering the geometry of buried and subsequently recovered skeletal remains. If pressure distortion is a frequent occurrence, it could systematically flaw the outcome of an anthropological examination. To study the patterns of post‐mortem distortion in buried crania and shape alterations associated with a specimen's in situ position, 46 male crania recovered from an Old Slavic graveyard (Pohansko, Czech Republic) were analysed together with control specimens from four modern European osteological collections (N = 207) using geometric morphometrics. The results indicate a common pattern of shape change in buried skulls associated with their in situ orientation. However, as the overall shape variation between the Old Slavic crania (which, with their tendency towards longer, narrower shapes differed markedly from the modern Czech crania) oriented in situ on their back and side reflects the duality of dolichocranial and brachycranial forms, it seems likely that the in situ positioning of the crania stemmed from their original morphology. The lack of substantial effect of the in situ orientation on the cranial morphology is associated with a larger cranial size and a tendency for sturdiness in the Old Slavic subsample. Both of these characteristics are likely to be contributing to the resistance of these crania to taphonomic alterations. Copyright © 2013 John Wiley & Sons, Ltd.     

The application of structured‐light illumination microscopy to hydrocarbon‐bearing fluid inclusions

Structured‐light illumination (SLI)‐based microscopy offers geologists a new perspective for screening of hydrocarbon‐bearing (HCFI) and small aqueous fluid inclusion (AFI) assemblages. This optical‐sectioning technique provides rapid, confocal‐like imaging, using relatively simple and inexpensive instrumentation. The 3D fluorescent images of HCFI planes and large single HCFIs permit the visualization of the relationships between HCFI assemblages, examination of HCFI morphology, and volume estimates of the fluorescent components within HCFIs. By the use of normal white light illumination, SLI image capture, and varying acquisition time it is also possible to image AFI because of the random movements of vapour bubbles within the inclusions. This allows the near‐simultaneous visualization of hydrocarbon and AFI which is of significant importance for the study of sedimentary basins and petroleum reservoirs. SLI is a unique and accessible 3D petrographic tool, with practical advantages over conventional epifluorescence and confocal laser scanning microscopy.     

DRS. MUTH AND MILLS MEET DR. TIEBOUT: INTEGRATING LOCATION‐SPECIFIC AMENITIES INTO MULTI‐COMMUNITY EQUILIBRIUM MODELS*

ABSTRACT We consider the problem of integrating spatial amenities into locational equilibrium models with multiple jurisdictions. We provide sufficient conditions under which models that assume a single housing price in each community continue to apply in the presence of location‐specific amenities that vary both within and across communities. If these conditions are satisfied, the models, estimation methods, and results in Epple and Sieg (1999) are valid in the presence of (potentially unobserved) location‐specific amenities. We also show how to construct sufficient statistics that capture location specific spatial heterogeneity. We apply these techniques using data from the Pittsburgh metropolitan area. We find that these amenity measures capture proximity to important local employment centers as well as heterogeneity in school quality within a given school district.     

Mapping Submerged Archaeological Sites using Stereo‐Vision Photogrammetry

Creating photo‐mosaics and plans of submerged archaeological sites quickly, cost‐effectively and, most importantly, to a high level of geometric accuracy remains a huge challenge in underwater archaeology. This paper describes a system that takes geo‐referenced stereo imagery from a diver‐propelled platform and combines it with mapping techniques widely used in the field of robotic science to create high‐resolution 2D photo‐mosaics and detailed 3D textured models of submerged archaeological features. The system was field tested on the submerged Bronze Age town of Pavlopetri off the coast of Laconia, Greece, in 2010. This paper outlines the equipment used, data collection in the field, image processing and visualization methodology.