H David Sheets

• PhD, Physics, SUNY at Buffalo
• Program Director at Merrimack College

The inconclusive category in forensics reporting is the appropriate response in many cases, but it poses challenges in estimating an “error rate”. We discuss the use of a class of information‐theoretic measures related to cross entropy as an alternative set of metrics that allows for performance evaluation of results presented using multi‐category...

Although extinction risk has been found to have a consistent negative relationship with geographic range across wide temporal and taxonomic scales, the effect has been difficult to disentangle from factors such as sampling, ecological niche, or clade. In addition, studies of extinction risk have focused on benthic invertebrates with less work on pl...

There has been extensive recent discussion of the difficulty in estimating meaningful error rates in forensic firearms examinations, and other areas of pattern evidence. The 2016 President's Council of Advisors on Science and Technology (PCAST) report was clear in criticizing many forensic disciplines as lacking the types of studies that would prov...

The symbiotic relationship between dinoflagellate algae in the family Symbiodiniaceae and scleractinian corals forms the base of the tropical reef ecosystem. In scleractinian corals, recruits acquire symbionts either “vertically” from the maternal colony or initially lack symbionts and acquire them “horizontally” from the environment. Regardless of...

This paper presents a new quantitative approach to the study of Asian lacquers using surface metrology, and two data science approaches: feature engineering and convolutional deep neural networks, as used in machine vision or image recognition applications. The types of Asian lacquers and additives have a quantifiable impact on the topography of th...

While type determination on bullets has been performed for over a century, type determination on cartridge cases is often overlooked. Presented here is an example of type determination of ejector marks on cartridge cases from Glock and Smith & Wesson Sigma series pistols using Naïve Bayes and Random Forest classification methods. The shapes of ejec...

We introduce the partial least squares (PLS) statistical analysis that quantifies and predicts the observed relationships among normal fault slip, fracturing associated with the fault, and lithology. We describe the systematic process for constructing a multivariate PLS model that predicts the average fracture frequency and the width of fracture-do...

Comparative Bullet Lead Analysis (CBLA) was discredited as a forensic discipline largely due to the absence of cross-discipline input, primarily metallurgical and statistical, during development and forensic/judicial application of the practice. Of particular significance to the eventual demise of CBLA practice was ignorance of the role of statisti...

Horizon annealing (HA) provides a method to order all horizons in a chronostratigraphic data set, including marker beds and isotopic excursions, as well as horizons that lack exact local markers (such as taxon first appearances) and are, thus, constrained only by local stratigraphical order. Global stratotype section and point (GSSP) levels placed...

Significance Climate change during Late Ordovician mass extinction drove an ecologically selective decline in the abundance of deep-water macrozooplankton, accompanied by a shift to simpler, less even communities. These results indicate that the species abundance structure of planktic communities may be a leading indicator of the effects of climate...

Abstract. Males of sibling orchid bees Euglossa viridissima and Euglossa dilemma are morphologically cryptic, except for the number and shape of mandibular teeth. An alternative morph of E. viridissima has a third tooth similar to males of E. dilemma. We used this model system to evaluate the potential of wing morphometrics for the resolution of th...

A new dataset of the highest quality specimens of fully articulated, juvenile and mature exoskeletons of the Czech middle Silurian trilobite Aulacopleura koninckii offers improved resolution of original morphology by all measures considered. The degree of variation in both size and shape among later meraspid instars was constant, and suggesting tar...

Chitinozoans are organic-walled microfossils that first appear in the Early Ordovician and diversify rapidly through the Paleozoic. They occur in a variety of marine paleoenvironments ranging from carbonate platforms to slope and basinal settings, but have an unknown taxonomic affinity. Along with graptolites and conodonts, chitinozoans are extreme...

Friction ridge impression appearance can be affected due to the type of surface touched and pressure exerted during deposition. Understanding the magnitude of alterations, regions affected, and systematic/detectable changes occurring would provide useful information. Geometric morphometric techniques were used to statistically characterize these ch...

A set of 137 Ordovician graptolite species were used to examine the associations among geographic range, sampling, biofacies and species longevity. Model-choice using general linear models combined with partial least-squares regression analysis found seven distinct predictive variables. The dominant factors were overall commonness, biofacies, geogr...

The Middle and Upper Ordovician rocks of Baltoscandia have been divided into spatially distinct, composite litho- and biofacies units called confacies belts. The precise regional correlation of outcrops and boreholes, which is necessary for biodiversity analyses, has always been problematic due to the pronounced biogeographical differentiation of m...

Hybridization between apple maggot, Rhagoletis pomonella (Walsh), and Rhagoletis zephyria Snow (Diptera: Tephritidae) occurs in Washington State, complicating fly identifications. Here, experimentally generated F 1 hybrids of R. pomonella and R. zephyria were classified using morphometric methods. Five of nine mean body size measurements of hybrids...

Fossilized ring‐like structures with enigmatic function and taxonomic affiliation were recovered for the first time from the Upper Ordovician of the Carnic Alps and the Silurian of Bohemia. These rings, already mentioned as minor constituents in previous conodont studies (e.g. Webers 1966, p. 1; Bischoff 1973, p. 147), were reported from the Palaeo...

Nearctic-neotropical passerines may spend up to one-third of the year in migration. Stopover sites have a critical role in providing migrant passerines with areas to rest and replenish fat stores. We characterized the stopover ecology of the Tennessee Warbler (Oreothlypis peregrina) at an inland site in Vicksburg, Michigan, using data from 4,607 wa...

An understanding of the variability of the anterior human dentition is essential in bitemark analysis. A collection of 1099 3D laser scans of paired maxillary and mandibular arches were studied using geometric morphometric methods. Analyses were performed without scale (shape only) and with scale (shape and size). Specimens differing by no more tha...

Comparative studies of ontogenies play a crucial role in the understanding of the processes of morphological diversification. These studies have benefited from the appearance of new mathematical and statistical tools, including geometric morphometrics, resampling statistics and general linear models. This paper presents an overview of how resamplin...

In this chapter, we discuss application of geometric morphometrics to the study of shape evolution. Because many of these studies examine multiple species, we pay particular attention to the role of phylogenetic information in analyses of phenotypic differences. We also present methods of quantifying and comparing morphological diversity (also know...

Studies of evolving ontogenies are grounded in two important insights. The first is that all evolutionary change arises from changes in ontogeny and therefore we need to understand how ontogenies evolve in order to understand the origins of morphological diversity. The second is that organisms have time-extended phenotypes. An organism’s phenotype...

Landmarks are discrete anatomical loci that can be recognized as the same point in all specimens in the study. They are often termed “homologous points” because these points can be matched up, one by one, as “the same point” in all individuals in the study. We could restrict the analysis to these points but we might miss a great deal of the morphol...

In the forensic sciences, as in biology, anthropology and paleontology, there is much interest in comparing the shapes of objects. There are several specific areas of forensics in which morphometric methods, both traditional and geometric, have been applied. In this chapter, we will first look at a morphometric approach that retains size informatio...

This chapter covers the basic theory of shape, beginning with the definition of shape and proceeding through the characterization of several theoretical spaces. Some of the mathematics may look a bit difficult, but it is important to grasp the basic ideas, which is presented verbally as well as mathematically. Interestingly, many of the techniques...

This chapter discusses methods for analyzing variational properties, phenotypic plasticity, canalization, developmental stability, morphological integration and the related property of modularity. This chapter is organized primarily by subject matter rather than by methods. We first discuss methods for analyzing plasticity, then canalization and th...

This chapter focuses on complex statistical models, such as models that include multiple categorical plus continuous factors, and those that include both fixed and random factors and those that include nested as well as crossed factors. All these models are special cases of the General Linear Model (GLM). We begin by introducing the GLM for simple...

Sheets, H.D., Mitchell, C.E., Izard, Z.T., Willis, J.M., Melchin, M.J. & Holmden, C. 2012: Horizon annealing: a collection-based approach to automated sequencing of the fossil record. Lethaia, Vol. 45, pp. 532–547. A number of different approaches to quantitative biochronology have been proposed and used to construct high-resolution time-scales for...

In bitemark analysis the extent of distortion of both maxillary and mandibular arches and how one affects the other has not been studied. A single dentition was used to create 49 bites on unembalmed cadavers. Landmarks were placed on digital images of the bitemarks and scanned images of the biting dentition. A sample of 297 randomly acquired dental...

The first edition of Geometric Morphometrics for Biologists has been the primary resource for teaching modern geometric methods of shape analysis to biologists who have a stronger background in biology than in multivariate statistics and matrix algebra. These geometric methods are appealing to biologists who approach the study of shape from a varie...

The morphological study of extinct taxa allows for analysis of a diverse set of macroevolutionary hypotheses, including testing for change in the magnitude of morphological divergence, extinction selectivity on form, and the ecological context of radiations. Late Ordovician graptoloids experienced a phylogenetic bottleneck at the Hirnantian mass ex...

The thin-plate spline provides a visually interpretable description of a deformation, with the same number of variables as there are statistical degrees of freedom, and it employs the Procrustes distance as a metric. Even if we were not concerned with the advantages of the spline for graphical analysis, we might still want to use it for purposes of...

Normalograptids constitute a distinctive but not easily identified group of derived axonophorans. A new study of Normalograptus morphology indicates that many Late Ordovician taxa previously identified as Normalograptus are actually referable to Styracograptus and related climacograptoids. These re-identifications have led to the recognition of a c...

Uniqueness of the human dentition is a fundamental premise in bitemark analysis. Despite the importance of this key aspect of bitemark methodology, systematic studies of large populations have been limited. Furthermore, there have been no investigations of the significance of the third dimension with regard to dental uniqueness. One hundred digital...

Phenotypic plasticity is a developmental process that plays a role as a source of variation for evolution. Models of adaptive divergence make the prediction that increasing ecological specialization should be associated with lower levels of plasticity. We tested for differences in the magnitude, rate and trajectory of morphological plasticity in tw...

Criticisms of the forensic discipline of bitemark analysis state that the range of distortion in the shape of bitemark impressions in skin has not been scientifically established. No systematic statistical studies exist that explore this problem. As a preliminary investigation of this issue, a single dentition was mounted in a mechanical apparatus...

Rhagoletis pomonella (Walsh) and Rhagoletis zephyria Snow (Diptera: Tephritidae) both occur in the U. S. Pacific Northwest and are frequently confused with one another due to their morphological similarity. The apple maggot, R. pomonella, is a threat to commercial apples [Malus domestica (Borkh.) Borkh.] in the Pacific Northwest, whereas R. zephyri...

  Forensically identifying a suspect’s dentition from a bitemark in an open population requires the supposition that every person’s dental alignment is different. There have been few studies that have tested this claim. Four hundred and ten lower anterior dentitions from a selected population and 110 lower anterior dentitions from one that was orth...

  Recent scrutiny of forensic science has focused on unreliability of expert witness testimony when based on statements of individuality. In bitemark analysis, assumptions regarding uniqueness of the dentition have been based on use of the product rule while ignoring correlation and nonuniformity of dental arrangement. To examine the effect of thes...

Landmark-based geometric morphometrics is a powerful approach to quantifying biological shape, shape variation, and covariation of shape with other biotic or abiotic variables or factors. The resulting graphical representations of shape differences are visually appealing and intuitive. This paper serves as an introduction to common exploratory and...

Skin is a less than ideal medium for recording bitemark impressions, and assessing the causes and magnitude of distortion has long been a question in forensic odontology. Affine methods have been suggested as a mathematical means to attempt to quantify the deformation typically seen with a bitemark. Thirty-six bites were created on unembalmed human...

Mixed breeding systems with extended clonal phases and weak sexual recruitment are widespread in nature but often thought to impede the formation of discrete evolutionary clusters. Thus, cyclic parthenogens, such as cladocerans and rotifers, could be predisposed to "species problems" and a lack of discrete species. However, species flocks have been...

The evolution of body size, the paired phenomena of giantism and dwarfism, has long been studied by biologists and paleontologists. However, detailed investigations devoted to the study of the evolution of ontogenetic patterns shaping giant species are scarce. The damselfishes of the genus Dascyllus appear as an excellent model for such a study. Th...

Landmark-based geometric morphometrics is a powerful approach to quantifying biological shape, shape variation, and covariation of shape with other biotic or abiotic variables or factors. The resulting graphical representations of shape differences are visually appealing and intuitive. This paper serves as an introduction to common exploratory and...

Rhagoletis pomonella (Walsh) (Diptera: Tephritidae) is a quarantine pest of apple (Malus sp.) in Washington state that is almost identical morphologically to Rhagoletis zephyria Snow, a nonpest of apple. Historically, the longer ovipositor in R. pomonella has been used to separate it from R. zephyria, despite overlap in ovipositor lengths. Here, th...

The hypothesis of coordinated stasis (CS) holds that taxa within ecological communities show a pattern of persistence over geologic time (faunal stability). This hypothesis has been examined by looking for evidence of stasis and change in paleocommunity structure based on patterns of taxon abundances obtained from bulk samples of fossil assemblages...

The impact of climate and ocean circulation changes on marine carbon and nitrogen cycling was investigated for a period covering the Late Ordovician Hirnantian glaciation. Three sections were studied: two from Nevada, one proximal and one distal; and one from the Yukon. The opportunity to compare δ13Ccarb, δ13Corg and δ13Cgrap profiles between ocea...

The Plus ça change model predicts that deepwater trilobite species such as Triarthrus should exhibit gradual phyletic evolution. A detailed stratigraphic sequence of Triarthrus beckii specimens considered together with geographically separated samples from a single time interval provide a test of the Plus ça change model. We examined geographic pat...

The hypothesis of coordinated stasis (CS) holds that taxa within ecological communities show a pattern of persistence over geologic time (faunal stability). This hypothesis has been examined by looking for evidence of stasis and change in paleocommunity structure based on patterns of taxon abundances obtained from bulk samples of fossil assemblages...

This study seeks to test appropriate sampling and statistical regimes for comparing biofacies compositions through the use of several statistical methods developed for analyzing community structure. Bulk sampled data from the Ambocoelia-chonetid biofacies within the Middle Devonian Hamilton Group of New York are used as a test data set. Samples wer...

Tectonic deformation is an important part of the taphonomic histories of many fossils. Although the effects of deformation, and methods to remove those effects, have been a subject of inquiry for over a century, systematic testing under known parameters has never been used to determine how the effects of deformation and the performance of retrodefo...

Evolutionary stasis has often been explained by stabilizing selection, intrinsic constraints, or, more recently, by spatially patterned population dynamics. To distinguish which of these mechanisms explains a given case of stasis in the fossil record, stasis must first be rigorously documented in a high-resolution stratigraphic time series of fossi...

Open population models using capture-mark-recapture (CMR) data have a wide range of uses in ecological and evolutionary contexts, including modeling of stopover duration by migratory passerines. In using CMR approaches in novel contexts there is a need to determine the conditions under which open population models may be employed effectively. Our g...

Geometric morphometric methods of capturing information about curves or outlines of organismal structures may be used in conjunction with canonical variates analysis (CVA) to assign specimens to groups or populations based on their shapes. This methodological paper examines approaches to optimizing the classification of specimens based on their out...

Canalization may play a critical role in molding patterns of integration when variability is regulated by the balance between processes that generate and remove variation. Under these conditions, the interaction among those processes may produce a dynamic structure of integration even when the level of variability is constant. To determine whether...

Although it is well known that many mutations influence phenotypic variability as well as the mean, the underlying mechanisms for variability effects are very poorly understood. The brachymorph (bm) phenotype results from an autosomal recessive mutation in the phosphoadenosine-phosphosulfate synthetase 2 gene (Papps2). A major cranial manifestation...

We have studied the pattern of graptolite species turnover during the latest Ordovician mass extinction based on four continuous Ashgillian to earliest Llandovery sections together with data from more than 30 other published sections. The studied sections represent relatively shallow-water and deeper-water belts in the Yangtze Platform region. Usin...

Hybridization receives attention because of the potential role that it may play in generating evolutionary novelty. An explanation for the emergence of novel phenotypes is given by transgressive segregation, which, if frequent, would imply an important evolutionary role for hybridization. This process is still rarely studied in natural populations...

Inferred group affinity and individual genotypic data. Genotypes of all specimens for 45 microsatellite loci (0 = missing data, alleles numbered according to size, but not necessarily repeat size) with group affinity and sampling site as of Table 3.

Individual landmark data, centroid size and sex. Cartesian coordinates (X – Y format) for fourteen landmarks, with individual group affinities and sampling site as of Table 3 as well as sex (0 = female; 1 = male) and centroid size.

Capture-mark-recapture models require estimation of parameters that may be either constant or time-dependent. Open-population models have been adapted for use in estimating stopover duration of migratory songbirds. However, with data collected over an extended period or with relatively few recaptures, small sample sizes may preclude use of fully ti...

One measure of the importance of a stopover site is the length of time that migrants spend at an area, however measuring the time birds spend at a stopover site has proven difficult. Most banding studies have presented only minimum length of stopover, based on the dif- ference between initial capture and final recapture of birds that are captured m...

Capture-mark-recapture models require estimation of parameters that may be either constant or time-dependent. Open-population models have been adapted for use in estimating stopover duration of migratory songbirds. However, with data collected over an extended period or with relatively few recaptures, small sample sizes may preclude use of fully ti...

This chapter discusses two methods for describing the diversity of shapes in a sample: principal components analysis (PCA) and canonical variates analysis (CVA). The discussion of these methods draws heavily on expositions presented by Morrison (1967), Chatfield and Collins (1980), and Campbell and Atchley (1981). Both methods are used to simplify...

This chapter presents a method for obtaining shape variables that is both simple and visually informative. Called “the two-point registration,” this method produces a set of shape coordinates, sometimes called “Bookstein shape coordinates,” that can be used both for graphical displays and formal statistical tests. Bookstein shape coordinates (BC) p...

Systematists use morphometrics to answer three types of questions. The first, “taxonomic,” asks whether populations are drawn from multiple species, and, if so, by what variable(s) they are most effectively discriminated. The second, “phylogenetic,” asks about phylogenetic relationships among taxa. Although they cannot be used to construct cladogra...

Many structures of interest to biologists are three-dimensional, or have few landmarks, or both. The skull of a marmot, like that of most mammals, is an example of “both.” The marmot skull is strongly curved anteroposteriorly and mediolaterally, making it highly three-dimensional (features on the same bone may be as far apart in the dorsoventral di...

This chapter covers methods for testing hypotheses about samples that vary along a continuously valued factor—a factor measured on an infinitely divisible scale. Size is an example of such a continuously valued factor because there is always a size between any two others; similarly, latitude is continuously valued because there is a latitude betwee...

This chapter aims to describe a variety of patterns that can be found in comparative studies of ontogeny. To that end, it focuses on the patterns amenable to discovery by comparative studies of ontogenetic allometry. Studies of allometry are sometimes viewed as a poor substitute for studies of heterochrony, but allometry is not just something we st...

This chapter begins with a brief review of groups and grouping variables. It then presents the simplest case, the test for a difference in one trait between two groups, and the methods that would be used in such cases. It follows this with a series of more complex analyses and the more generalized methods that would be applied to them. The final se...

Landmarks are discrete anatomical loci that can be recognized as the same loci in all specimens in the study. As landmarks play a fundamental role in geometric morphometrics, it is important to understand their function in a shape analysis. It is equally important to understand which functions they do not serve, as that understanding also influence...

This chapter presents a brief discussion of some of the basic statistical concepts that are needed to understand statistical methods in general (such as confidence intervals and hypothesis testing), as well as the more specialized concepts that are needed to understand computer-based statistical methods. Four classes of these methods are presented,...

Disparity and variation are closely allied concepts—both refer to the general idea of “variety.” Disparity usually signifies the variety of a group of species and is the outcome of evolutionary processes; variation, on the other hand, refers to the variety of individuals within a single (homogeneous) population and is the raw material necessary for...

Geometric Morphometrics for Biologists is an introductory textbook for a course on geometric morphometrics, written for graduate students and upper division undergraduates, covering both theory of shape analysis and methods of multivariate analysis. It is designed for students with minimal math background; taking them from the process of data colle...

Heterochrony, evolutionary changes in rate or timing of development producing parallelism between ontogeny and phylogeny, is viewed as the most common type of evolutionary change in development. Alternative hypotheses such as heterotopy, evolutionary change in the spatial patterning of development, are rarely entertained. We examine the evidence fo...

Landmark based geometric morphometrics has developed as a powerful set of statistical and visual tools for the study of the covariance patterns of organismal shape change with a range of variables or factors. The approach is limited in the kinds of shape information accessible to it, however, by the need to employ discrete landmarks as the basis fo...

Variation in neonatal maturity among mammals is often explained by variation in gestation length, but species may also differ in developmental rate, a quantity that is difficult to measure because the conventional formalism makes two important and potentially unrealistic assumptions: (1) ontogeny of form can be described by a single line, and (2) s...

To the extent that growth markers provide more information about developmental processes than is typically available in ontogenetic shape analyses, analyses of them are richer than those relying on size and shape data alone. Most workers will not have access to that kind of data because most species do not naturally record growth processes, and few...