H David Sheets

H David Sheets
Canisius College · Data Analytics

PhD, Physics, SUNY at Buffalo

About

109
Publications
26,877
Reads
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7,771
Citations
Introduction
Hello All- Please note that Geometric Morphometrics for Biologists: A Primer, is a published textbook and not available as a download.
Additional affiliations
January 2011 - present
University at Buffalo, The State University of New York
January 2001 - present
Canisius College
Position
  • Professor

Publications

Publications (109)
Article
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...
Article
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...
Article
Full-text available
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...
Article
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...
Article
Full-text available
Mass extinctions disrupt ecological communities. Although climate changes produce stress in ecological communities, few paleobiological studies have systematically addressed the impact of global climate changes on the fine details of community structure with a view to understanding how changes in community structure presage, or even cause, biodiver...
Article
Full-text available
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...
Article
Full-text available
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...
Poster
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...
Article
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...
Article
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...
Article
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...
Article
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
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...
Article
Full-text available
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...
Chapter
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...
Chapter
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...
Chapter
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...
Chapter
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...
Chapter
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...
Chapter
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...
Chapter
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...
Article
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...
Article
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...
Book
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...
Article
Full-text available
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...
Chapter
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...
Article
Full-text available
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...
Article
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...
Article
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...
Article
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...
Article
Full-text available
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...
Article
  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...
Article
  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...
Article
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...
Article
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...
Article
Full-text available
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...
Article
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...
Chapter
Full-text available
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...
Article
Full-text available
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...
Article
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...
Article
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...
Article
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...
Article
Full-text available
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...
Article
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...
Article
Full-text available
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...
Article
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
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...
Article
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...
Article
Full-text available
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...
Article
Full-text available
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...
Data
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.
Data
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.
Article
Full-text available
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...
Article
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...
Article
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...