Elliptic Fourier Analysis Research Articles

Assessment of the mechanical properties of Tarocco orange fruit under parallel plate compression

In this work the mechanical compressive properties of orange fruits of the Tarocco variety were assessed using a Universal Testing Machine, equipped with upper and lower plates made of transparent graduated Plexiglas® and three cameras positioned along the axis lines x, y and z. By submitting each fruit to different engineering strains ( ε z ) along the z-axis in the range of 3–21% of the initial fruit height, the momentary contact area of each fruit under testing was precisely determined by approximating its outline to a polygon and reconstructing it via the Elliptic Fourier Analysis, or an ellipse inscribed in a bounding box. Both estimates yielded no statistically significant difference and varied linearly with ε z . Their prediction using the ASABE Standard Method (2008), or assuming no variation in the volume of the fruit undergoing compression, resulted be under- or over-estimated by 45% or 19%, respectively. Use of image analysis allowed the apparent Poisson’s ratio and modulus of deformability ( E O) of the whole orange fruit to be estimated as equal to 0.16 ± 0.09 and 353 ± 3 kPa, respectively. By assimilating the orange fruit to a deformable membrane ( flavedo) filled with an internal incompressible juice, it was possible to estimate the compressive stress acting on the equatorial horizontal cross-section of the epicarp only and thus estimate the apparent modulus of elasticity of the orange peel (=375 ± 33 kPa), and a burst pressure of 533 ± 103 kPa at a rupture strain ε z R of 0.30 ± 0.03 for rind thicknesses ranging from 0.8 to 4.0 mm.

Quantitative assessment of interproximal wear facet outlines for the association of isolated molars

The determination of the minimum number of individuals can be very challenging, especially in an assemblage of fragmentary bones and isolated teeth. Similarities in tooth morphology, degree of wear, and interproximal wear facets (IPWF) are generally used to associate isolated teeth qualitatively. However, no quantitative method has yet been established for an objective identification and matching of isolated tooth crowns. In this study, we analyze the IPWF morphology of adjacent mandibular molars (17 M(1)/M(2) pairs), applying both qualitative and quantitative methods to test a reproducible approach for crown association. The surfaces of distal (for M(1)) and mesial (for M(2)) IPWF were surface-scanned and digitally selected. Three-dimensional (3D) and two-dimensional (2D) outlines of IPWF were analyzed using elliptic Fourier analysis (EFA) and geometric morphometrics methods (GMM). Additionally, teeth were qualitatively associated by visual evaluation of the IPWF outline and by physical matching. Unsatisfactory results with less than 50% of tooth pairs correctly associated were obtained by using both methods, shape analysis (digital approach) and the visual evaluation (qualitative assessment) of the IPWF outline. The physical matching of the crowns showed highly variable accuracy ranging between 53% and 77%. The quantitative form-space analysis of 2D IPWF outlines provided the best results (82% of correctly associated teeth), but no statistically significant differences were recorded when compared with the manual matching. Since three tooth pairs out of 17 could not be quantitatively associated, we suggest that the quantitative analysis of IPWF should be used only in addition with other approaches.

Cicada ear geometry: species and sex effects

Many insect species rely on their sense of audition to find a mate, to localize prey or to escape from a predator. Cicadas are particularly known for their loud call and the conspicuous tympanal hearing system located in their abdomen. The vibration pattern of the tympanal membrane (TM) has been investigated recently revealing mechanical properties specific to species and sex. Although TM size and shape is likely to affect these patterns, the geometry of the cicada ear has never been examined per se. Focusing on three Mediterranean cicada species, namely Cicadatra atra, Cicada orni and Lyristes plebejus, we investigated the structure of TM shape variation at two levels, within and across species. Applying an elliptic Fourier analysis to the outlines of both male and female TMs, we estimated sexual dimorphism and species effects. Cicadatra atra showed a large TM compared with its small size, probably as a result of selective constraints related to the role of the TM in sound production. Sexual dimorphism seemed to be greater than interspecific variation, indicating that constraints operating on sex might be more selective than those acting on species identification. In addition, C. orni appeared to be significantly different from the two other species. This morphological peculiarity could be related to the unique vibrational pattern of its membrane. This would establish for the first time a direct link between the shape and mechanism of a hearing organ.

Chirally dimorphic male genitalia in praying mantids (Ciulfina: Liturgusidae)

Although male polymorphisms occur widely in nature and have received considerable recent attention from studies of alternative mating strategies, male genital polymorphisms are less well known. Here, we describe a dimorphism in the orientation of the male genitalic complex of the praying mantid genus Ciulfina. Populations of Ciulfina species vary in the proportion of males with dextral (right-oriented) and sinistral (left-oriented) genitalia, ranging from directional asymmetry (single orientation only) to apparent antisymmetry (equal proportions of both orientations). The proportion of dextral males varied between species (C. baldersoni: 46%; C. rentzi: 24%; C. klassi: 100%; C. biseriata: 83%) and between populations. We used elliptic Fourier analysis to quantify shape and size variation between the genitalia of dextral and sinistral males and determined that the two forms were mirror images of one another in two species. We found that the level of mechanical reproductive isolation between heterospecific populations of opposite genital orientation was no greater than that between heterospecific populations with the same orientation or of mixed orientation. Genital orientation therefore did not influence premating isolation between these species, despite complete postmating isolation. The geographic proximity of populations to heterospecifics also showed no particular pattern with respect to genital orientation. These results suggest that reversible trait asymmetry in Ciulfina is not driven by reproductive isolation, and add to the growing evidence against the species isolation hypothesis for rapid genital evolution.

Otolith retrieval from faeces and reconstruction of prey-fish size for Great Cormorant (Phalacrocorax carbo) wintering at the East Dongting Lake National Nature Reserve, China

The food composition of Great Cormorant (Phalacrocorax carbo) was studied by analyzing 360 faecal samples collected from their roosting sites at the East Dongting Lake National Nature Reserve in south-central China during November 2008 and January 2009. A total of 223 fish otoliths were retrieved. Only sagittal otoliths (N = 74) with intact margins, good medial relief, and well-defined sulcus were used to identify the prey-fish species and to reconstruct prey-fish size. Through shape indices and elliptical Fourier analyses, these otoliths were identified as belonging to two cyprinid fish species, crucian carp Carassius auratus (72%) and white amur bream Parabramis pekinensis (28%). The otolith size (maximum length, Lo)—prey-fish size (standard length, Ls) relationships determined for the two fish species were Ls = −19. 5 + 37.1 Lo (N = 74; R2 = 0.95; P < 0.05) for crucian carp and Ls = −31.9 + 36.9 Lo (N = 70; R2 = 0.97; P < 0.05) for white amur bream. The back-calculated Ls from the otoliths retrieved from the faeces were 96.2 ± 10.2 mm (range 72.7–110.4 mm) for crucian carp and 86.3 ± 10.4 mm (range 74.1–104.6 mm) for white amur bream. Based on setnet sampling of the fish community near roosting sites, crucian carp and white amur bream were found as the first and second most abundant species. Great Cormorants were very selective for the size range of prey. These results demonstrate that analysis of otoliths retrieved from faeces can be an effective, inexpensive, and non-invasive method to identify prey-fish species and to estimate prey-fish size in studies of diet composition for piscivorous birds.

A comparison of otolith microchemistry and otolith shape analysis for the study of spatial variation in a deep-sea teleost, Coryphaenoides rupestris

The study of the morphological and chemical characteristics of otoliths have recently been proposed as complementary tools for fish stock identification. However, their effectiveness remains to be fully assessed, especially in species whose life history is still poorly understood. The relative efficiency of otolith microchemistry and otolith shape analysis in discriminating samples of the deep-sea macrourid Coryphaenoides rupestris collected in different areas in the North Atlantic was examined. Otolith microchemistry based on LA/ICP-MS found significant differences in the concentrations of lithium, manganese and barium among sample sites. This allowed for very high classification accuracy (92%), when using discriminant function analysis. Otolith shape analysis based both on linear shape measurements and elliptical fourier analysis revealed a contrasting weak discrimination, with only 43% classification success. Otolith microchemistry appears to be a more effective tool in identifying individual fish from different locations. The implications for the study of population structure are discussed taking into account the limitations of the methodologies employed.

Quantitative Method for Shape Description of Almond Cultivars (Prunus amygdalus Batsch)

The aim of the present work was to propose a rapid, non-invasive, and quantitative image analysis method based on elliptic Fourier analysis (EFA) and on carpological measurements to discriminate between 18 cultivars and shape groups of almond kernels and in-shell fruit. The shape groups were identified using two clustering techniques: a non-hierarchic method (k-means) and a hierarchical one (Ward’s method). Both methods found the same numbers of groups for in-shell fruit and kernels. The obtained results indicate that such differences can be used to discriminate among shape groups. This method was not efficient in discriminating single cultivars. In order to classify fruit into shape groups, a partial least squares discriminant analysis was applied. This analysis applied on the 18 cultivar groups showed low percentages of correct classification for both in-shell (38.58%) and kernels (31.36%). The same analysis computed on shape groups shows percentages of correct classification higher than 89%. Merging EFA, clustering methods, and modeling techniques set the basis for the implementation of an automated online fruit sorting. A Matlab script was developed to determine the right number of clusters in k-means clustering.

A geometric morphometric assessment of the optic cup in glaucoma

The morphologic appearance of the optic disc is of interest in glaucoma. In contrast to descriptive classification systems that are currently used, a quantitative approach to the analysis of optic disc morphology is required. Our goal was to determine the optimal method for quantifying optic cup shape by comparing traditional (ovality, form-factor and neuroretinal rim (NRR) width ratio) and geometric morphometric approaches. Left optic disc stereophotographs of 160 (80 normal and 80 glaucomatous (stratified by severity)) subjects were examined. The optic cup margins were stereoscopically delineated with a custom tracing system and saved as a series of discrete points. The geometric morphometric methods of elliptic Fourier analysis (EFA) and sliding semi-landmark analysis (SSLA) were used to eliminate variation unrelated to shape (e.g. size) and yield a series of shape variables. Differences in optic cup shape between normal and glaucoma groups were investigated. Discriminant functions were computed and the sensitivity and specificity of each technique determined. Receiver operator characteristic (ROC) curves were calculated for all methods and evaluated in their potential to discriminate between normal and glaucomatous eyes based on the shape variables. All geometric morphometric methods revealed differences between normal and glaucomatous eyes in optic cup shape, in addition to the traditional parameters of ovality, form-factor and NRR width ratio ( p < 0.0005). SSLA (minimum bending energy criterion – 18 points) had the best sensitivity (83%) and area under the curve (AUC) (0.91). EFA (72 points) performed similarly well (74%, 0.89) as did the set of traditional shape-based variables (76%, 0.86). This study demonstrated that a geometric morphometric approach for discriminating between normal and glaucomatous eyes in optic cup shape is superior to that provided by traditional single parameter shape measures. Such analytical techniques could be incorporated into future automated optic disc screening modalities.

The case of an insular molarless black rat: Effects on lifestyle and mandible morphology

We report a specimen of an insular black rat ( Rattus rattus) from Illa den Colom (Menorca, Western Mediterranean) displaying a singular dental characteristic. It has no molar teeth but displays regular incisors. Its mere occurrence as a regular adult rat is puzzling and we attempted to evaluate what diet and morphological changes in jaw shape were promoted by the total lack of molars, and allowed the successful survival of this specimen. Two approaches were performed: first, bone tissue was analysed to obtain δ 15N and δ 13C values in order to estimate dietary preferences of the rat. Second, the shape of the jaw was analysed through elliptic Fourier analysis, using outlines as markers of diet. The values for C and N fractionation (−19.89‰ and 10.06‰, respectively) suggest that the molarless rat included animal food in the diet and not exclusively plant material as observed in other mainland rat populations. The morphometric analysis in which the shape of the molarless mandible falls into the range of omnivorous groups leads to a similar conclusion. The adult age of the specimen suggests that it fed efficiently enough with its incisors to allow a normal growth. Although displaying a lack of molar teeth, no deep changes in remodelling jaw morphology can be observed and its shape falls into the variation of regular murines. The molarless rat exemplifies that special ecological features on small islands allow the survival of aberrant morphotypes.

Phylogeography and demographic inference in Nacella ( Patinigera) concinna (Strebel, 1908) in the western Antarctic Peninsula

Endemic to Antarctic ecosystems, the limpet Nacella ( Patinigera) concinna (Strebel, 1908) is an abundant and dominant marine benthic invertebrate of the intertidal and shallow subtidal zone. In order to examine the phylogeographic pattern and historical demography of the species along the western Antarctic Peninsula, we amplified 663 bp of the mitochondrial DNA cytochrome oxidase subunit I of 161 N. concinna specimens from five localities, as well as two specimens from South Georgia and Sub-Antarctic Marion Island. As two different morphotypes, one characterized by an elevated shell in the intertidal and the other by a flat one in the subtidal, have been recurrently reported for this species, we also compared intertidal and subtidal samples from two localities of King George Island (Admiralty and Fildes Bay) through geometric morphometric and genetic analyses. As a result, elliptic Fourier analyses on shell shape morphology detected highly significant differences between intertidal and subtidal morphotypes. In contrast, mtDNA analyses between these morphotypes did not detect statistical differences between them and support the hypothesis that subtidal and intertidal N. concinna forms correspond to be the same population unit. Genetic analyses depicted low levels of haplotypic and nucleotide diversity in N. concinna in all localities. Among populations, comparisons did not detect any genetic structure, supporting the existence of a single genetic unit along the western Antarctic Peninsula. A marked L-shaped distribution of pairwise differences and significant negative Tajima’s D and Fu’s F S indices suggest the existence of a recent demographic expansion of this species. Time estimations corrected by the “time dependency of molecular rate” hypothesis for this demographic event (7,500–22,000 years ago) fit well with the last glacial–interglacial transition period. Low levels of genetic diversity in N. concinna could reflect the dramatic effect of glacial periods on population sizes, especially in Antarctic species with narrow bathymetric ranges. Genetic similarities between South Georgia and Antarctic samples, as well as between Nacella delesserti (Philippi, 1849) and N. concinna (Strebel, 1908) fell within the range of intraspecific variation. The genetic proximity between sub-Antarctic N. delesserti and the Antarctic limpet could be explained through north-eastward long-distance dispersion events during the late Pleistocene.

Shell variability in Tawera gayi (Veneridae) from southern South America: a morphometric approach based on contour analysis

This study analyses the significance of shell morphological variations in the venerid clam Tawera gayi, a typical element of shallow marine soft bottoms in southern South America and the most common species recovered from Late Quaternary marine deposits along the Beagle Channel, Tierra del Fuego. Fossil and modern Tawera shells from different localities around the southern tip of South America were analysed using the Elliptic Fourier Analysis (EFA) method. Taking into account the palaeontological history of this genus in the southern hemisphere, EFA was also performed on shells of Tawera congeners from South Africa (T. philomela) and New Zealand (T. spissa). The use of EFA permitted the distinction between the three Tawera species and geographical differentiation in the T. gayi groups. These morphological variations of T. gayi appear best related to ecophenotypic plasticity as a response to different environmental conditions, although the palaeobiogeographical history of Tawera in South America cannot be ruled out.

Sexual dimorphism in the shape of the primary wing and tail feathers of the sky blue parakeet (budgerigar), Melopsittacus undulatus (Shaw, 1805) (Psittaciformes: Psittacidae)

Difference between sexes was quantified in this study using outline based-geometric morphometric analysis on the shape of the primary wing and tail feathers of the sky blue strain of parakeet bird Melopsittacus undulatus (Shaw, 1805). Results of Discriminant Function Analysis (DFA) and Principal Component Analysis (PCA) utilizing the coefficients derived from Elliptic Fourier Analysis (EFA) consistently showed that sexual dimorphism is present in the said species with differences primarily explained by the variations in the tip and outline of the flight feathers. Females generally have slightly rounded tip and partially curved (inward) feather outline while males have feathers with slightly pointed tip and more or less straight feather outline. However, no difference between sexes was observed in the shape of tail feathers. It is suggested that based from this study, a more complete understanding and proper identification on the biological basis of the observed wing shape differences are needed which could be elemental in the proper and effective conservation of this species.

Describing variations in scales between sexes of the yellowstriped goatfish, Upeneus vittatus (Forskål, 1775) (Perciformes: Mullidae)

Scales have numerous hidden details in their sculptural design that contributes effectively to fish identification and classification. A traditional approach has been made to study the scale morphology of the yellow striped goatfish Upeneus vittatus (Forskal, 1775) using a micron cam attached to a Gateway computer and a stereomicroscope in tandem with a 14 megapixel Kodak easyshare Z 1485 IS digital camera in which digitized images were processed using Corel Paint Photoshop 2x program. To eliminate subjective human error, scale variation in scale images were subjected to Elliptic Fourier Analysis using 77 Fourier descriptors and Principal Component Analysis to discriminate variation between scale shapes within the male and female U. vittatus and to use the data generated to established variation between male and female species. Scanned images (1200dpi) were binarized to generate chain codes using SHAPE 1.3 version. The data were analyzed using Principal Component Analysis conducted using the PAST software ver. 1.8. Result of the study revealed that there is a high significance in the variation of shapes within male and female individuals of U. vittatus and that a significant variation in scale shapes was observed between male and female species. This study demonstrated that scale characteristics can provide useful taxonomic information on the morphological differences between sexes of U. vittatus and that elliptic Fourier analysis and principal Component analysis are good tools to discriminate variation in scale shapes.

Shape differentiation and characterization in the two morphotypes of the Antarctic limpet Nacella concinna using Elliptic Fourier analysis of shells

The Antarctic limpet Nacella concinna (Strebel 1908) presents two ecotypes (littoral and sublittoral) differing in morphological and behavioral characteristics and more recently discovered, in physiological traits and genetic population structure. Previous works, based on traditional morphometry, used only three measurements (length, width and height of the shell) and their relationships. However, this methodology could not describe in detail the shape of the morphotypes. In the present work, Elliptic Fourier analysis (EFA) of shells was used to study the shape of the two morphotypes in six localities along the Antarctic Peninsula. The use of EFA confirmed the morphometric differences. The littoral morphotype has higher and globose shells with the apex displaced to the anterior part; the sublittoral individuals are more flat and pointed, and have the apex very well defined. Low allometric effect was detected in SL individuals, whereas L specimens did not show an allometric relationship within the examined size range. Differences in shell shape among localities were recorded. EFA analysis reflected the overall shell shape and allowed to characterize the main differences in shell shape between ecotypes that were difficult to quantify using the standard morphometric approach.

Elliptic Fourier Analysis of leaf outline shape in forest fragment populations of Anthurium sinuatum and A. pentaphyllum (Araceae) from Northeast Brazil

A field-based comparative study of leaflet outline shape in five populations of Anthurium sinuatum Benth. ex Schott from Amazonia and humid brejo forests of Ceara, Northeast Brazil, and ten populations of A. pentaphyllum (Aubl.) G. Don var. pentaphyllum from Amazonia and the Brazilian Atlantic forest is reported. 1,120 leaflets from 561 individuals in 15 populations were sampled. Using images, leaflet outlines were captured by digitisation and subjected to Elliptic Fourier Analysis (EFA) to produce matrices of Fourier coefficients based on 40 harmonics; lateral and central leaflets were analysed separately. Twelve shape variables, extracted from the Fourier coefficient matrices, described the leaflet outlines of 531 individuals. Between-population relationships were estimated using cluster analysis, Canonical Variates Analysis and non-parametric MANOVA. Amazonian populations showed the greatest within-population variability. In A. sinuatum the Pacatuba population was the most distinct in Ceara and the Para population (Amazonia) was not significantly different from those at Ibiapaba and Maranguape (both Ceara). In A. pentaphyllum 80% of population pairs were significantly different and three significantly different groups of populations were observed. Although the populations of A. pentaphyllum displayed considerable variation, the morphological patterns did not correlate with previously reported molecular ones. The two species were found to be slightly but significantly different on leaf outline data.

Identifying hybridizing taxa within the Daphnia longispina species complex: a comparison of genetic methods and phenotypic approaches

Daphnia galeata Sars, D. longispina O. F. Muller and D. cucullata Sars (Crustacea: Cladocera) are closely related species which often produce interspecific hybrids in natural populations. Several marker systems are available for taxon determination in this hybridizing complex, but their performance and reliability has not been systematically assessed. We compared results from identifications by three molecular methods. More than 1,200 individuals from 10 localities in the Czech Republic were identified as parental species or hybrids by allozyme electrophoresis and the analysis of the restriction fragment length polymorphism of the internal transcribed spacer (ITS-RFLP); over 440 of them were additionally analyzed and identified by 12 microsatellite loci. Identification by microsatellite markers corresponded well with allozyme analyses. However, consistent discrepancies between ITS-RFLP and other markers were observed in two out of 10 studied localities. Although some marker discrepancies may have been caused by occasional recent introgression, consistent deviations between ITS-RFLP and other markers suggest a long-term maintenance of introgressed alleles. These results warn against its use as a sole identification method in field studies. Additionally, we quantitatively evaluated the discriminatory power of geometric morphometric (elliptic Fourier) analysis of body shapes based on photos of over 1,300 individuals pre-classified by allozyme markers. Furthermore, a randomly selected subset of 240 individuals was independently determined from photos by several experts. Despite a tendency for morphological divergence among parental Daphnia species, some taxa (especially D. galeata, D. longispina, and their hybrids) substantially overlapped in their body shapes. This was reflected in different determination success for particular species and hybrids in discriminant analysis based on shape data as well as from photographs.

Sex identification of Carcinus maenas by analysis of carapace geometrical morphometry

The European green crab Carcinus maenas is a widely spread invasive species. Studying the most recently introduced population of the species in the Atlantic coast off Patagonia, it became apparent to us that carapaces (the dorsal cover of the visceral-cavity detaching from the rest of the exoskeleton after ecdysis) accumulated on the intertidal may be used as a valuable complementary material to analyze the size structure of crabs. However, since growth rate (and consequently size at instar) of crabs differs between males and females, finding a method to distinguish crab sex by observation of carapace morphology was necessary to allow the construction of independent size frequency distributions for each sex. In this work, we examined the shape of the carapaces from both sexes of C. maenas, and using Elliptical Fourier Analysis successfully identified sexual dimorphism. Thus, a reliable method to identify sexes by visual observation of the carapace was developed. Based on our results, we discuss the evolutionary significance of carapace form differentiation of both sexes.

Comparison of morphometric techniques for shapes with few homologous landmarks based on machine-learning approaches to biological discrimination

Biometric analyses are useful tools for the study of organisms, their phylogenetic affiliation, and the pattern and rate of their evolution. Various morphometric techniques have been developed to analyze morphological variation, but methodological choices are often made arbitrarily because quantitative comparisons are lacking or inconclusive. Here we address morphometric quantification of taxa with few unambiguously identifiable landmarks (&lt;15), utilizing ornamented and unornamented gastropod shells. Support vector machines were applied to evaluate classification performances of landmark (LMA), elliptic Fourier (EFA), and semi-landmark analysis (SLM). This evaluation is based on the discrimination of between-group differences relative to within-group variation, and thus allows comparing how the techniques treat different types of biological information. The results suggest that EFA performs slightly better than SLM (and certainly LMA) in discerning a priori identified taxa with unornamented shells, but that SLM is significantly superior to other techniques for ornamented shells. Alignment and homology problems may cause the subtle variations in ornamentation to become blurred as noise in EFA, even though EFA is often cited to be able to deal with complex shapes. Performance of LMA depends entirely on how accurately the structure can be covered with landmarks. Guidelines in choosing a morphometric technique in diverse cases are provided.

Height and body mass influence on human body outlines: A quantitative approach using an elliptic Fourier analysis

Many studies use representations of human body outlines to study how individual characteristics, such as height and body mass, affect perception of body shape. These typically involve reality-based stimuli (e.g., pictures) or manipulated stimuli (e.g., drawings). These two classes of stimuli have important drawbacks that limit result interpretations. Realistic stimuli vary in terms of traits that are correlated, which makes it impossible to assess the effect of a single trait independently. In addition, manipulated stimuli usually do not represent realistic morphologies. We describe and examine a method based on elliptic Fourier descriptors to automatically predict and represent body outlines for a given set of predicted variables (e.g., sex, height, and body mass). We first estimate whether these predictive variables are significantly related to human outlines. We find that height and body mass significantly influence body shape. Unlike height, the effect of body mass on shape differs between sexes. Then, we show that we can easily build a regression model that creates hypothetical outlines for an arbitrary set of covariates. These statistically computed outlines are quite realistic and may be used as stimuli in future studies.

Morphological criteria for recognising homology in isolated skeletal elements: comparison of traditional and morphometric approaches in conodonts

Abstract: Accurate hypotheses of primary homology are fundamental to many aspects of the systematics and palaeobiology of fossils. They are particularly critical for conodonts: virtually all areas of conodont research are underpinned by homology, yet the majority of conodont taxa are found only as disarticulated skeletal elements, and hypotheses of element homology are inferred from morphological comparisons with complete skeletons. This can cause problems in taxa where more than one location within the conodont skeleton is occupied by elements with similar morphology. In such cases, morphological comparisons can yield equivocal or erroneous hypotheses of homology of isolated elements. The Eramosa Lagerstätte of Ontario (Silurian, Wenlock) preserves both isolated skeletal elements and articulated conodont skeletons. The latter provide a topological context within which to test hypotheses of element homology and allow blind testing of qualitative discrimination of elements. When applied to P1 and P2 elements of Wurmiella excavata, this revealed inaccuracy and inconsistency in distinguishing these P element types. Standardised morphometric protocols were used to further test the efficacy of those characters used in traditional qualitative identification of P element homology, revealing that, individually, none of these characters provides an effective discriminator between P element types. Principal components and discriminant function analyses of ten ‘traditional’ morphological variables combined can distinguish P1 from P2 elements with a similar success rate to expert identification. Eigenshape and elliptic Fourier analyses of element outlines proved less effective at capturing shape differences that allowed for discrimination between P1 and P2 elements. Analysis of both traditional and outline data demonstrates that in some individuals P1 and P2 elements are morphologically distinct from one another, while in others they are almost indistinguishable. These results demonstrate that although qualitative assessments of homology can be prone to error, especially when undertaken by inexperienced researchers, the morphometric and analytical protocols used here provide effective additional tool for discriminating morphologically similar but non‐homologous elements. These methods thus hold promise of broad application to other conodont taxa where identification of element homology in collections of isolated specimens is problematic.