scholarly journals Illustrating ontogenetic change in the dentition of the Nile monitor lizard, Varanus niloticus : a case study in the application of geometric morphometric methods for the quantification of shape-size heterodonty

2015 ◽  
Vol 226 (5) ◽  
pp. 403-419 ◽  
Author(s):  
Domenic C. D'Amore
Keyword(s):  
Ontogenetic Change ◽  
Geometric Morphometric ◽  
Monitor Lizard ◽  
Morphometric Methods

scholarly journals A Comparison of Traditional and Geometric Morphometric Techniques for the Study of Basicranial Morphology in Horses: A Case Study of the Araucanian Horse from Colombia

Animals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 118
Author(s):  
Pere Miquel Parés-Casanova ◽  
Arcesio Salamanca-Carreño ◽  
René Alejandro Crosby-Granados ◽  
Jannet Bentez-Molano
Keyword(s):  
Geometric Morphometrics ◽  
Domestic Animal ◽  
New Techniques ◽  
Geometric Morphometric ◽  
Animal Populations ◽  
Morphometric Methods ◽  
Mature Group ◽  
Geometric Morphometric Analysis ◽  
Shape And Size

Skull size and shape have been widely used to study domestic animal populations and breeds. Although several techniques have been proposed to quantify cranial form, few attempts have been made to compare the results obtained by different techniques. While linear morphometrics has traditionally been used in breed characterization, recent advances in geometric morphometrics have created new techniques for specifically quantifying shape and size. The objective of this study was to compare two morphometric methods for their ability to describe external morphology. For this purpose, 20 skull specimens of adult male Araucanian horses were examined. Two age categories were established (the “mature group”, M3 not fully erupted to moderately worn, n = 7; and the “senile group”, M3 totally erupted and highly worn, n = 13). Both methods showed that there were statistical differences between generations, but discrimination rates were different between methods with the geometric morphometric analysis obtaining a rate of 97.5%. Although linear morphometrics was found to be compatible with geometric morphometrics, the latter was better able to discriminate the two groups and it also provides more information on shape.

Is there a better chela to use for geometric morphometric differentiation in brachyuran crabs? A case study using Pachygrapsus marmoratus and Carcinus maenas

2008 ◽  
Vol 88 (5) ◽  
pp. 941-953 ◽  
Author(s):  
Inês C. Silva ◽  
José Paula
Keyword(s):  
Carcinus Maenas ◽  
Genetic Data ◽  
Geometric Morphometric ◽  
Morphometric Methods ◽  
Pachygrapsus Marmoratus ◽  
Brachyuran Crabs ◽  
The Right ◽  
Geographical Locations ◽  
Shape Differentiation

Landmark-based geometric morphometric methods were used to test which chela is most suitable to use in population differentiation of brachyuran crabs. Two species were analysed: Pachygrapsus marmoratus, a homochelous species, and Carcinus maenas, a heterochelous species. Variance analysis of shape variables and of each chela was calculated to determine which claw presents less variation within populations. The results showed that the right chela of P. marmoratus is more appropriate to use when the goal is to differentiate populations. In C. maenas, the males major chela and females right chela are more suitable to use, probably due to its heterochely. To test these results, specimens from different geographical locations were compared. Pachygrapsus marmoratus populations presented significant differences in manus shape, and C. maenas populations had differences in polex size and shape. Differences in carapace shape were also encountered between populations of both species. This phenotypic variation was not corroborated with genetic data, which were obtained using the mitochondrial DNA gene cytochrome oxidase I as a marker. These opposite results suggest that environmental factors, such as diet and parasitism, can be determining shape differentiation.

scholarly journals Standardization of ceramic shape: A case study from the Iron Age pottery from northeastern Taiwan

2020 ◽  
Author(s):  
Li-Ying Wang ◽  
Ben Marwick
Keyword(s):  
Iron Age ◽  
Craft Specialization ◽  
Pottery Production ◽  
Geometric Morphometric ◽  
Landmark Analysis ◽  
Coefficients Of Variation ◽  
Morphometric Methods ◽  
Ceramic Vessels ◽  
Outline Analysis

The emergence of ceramic specialization in prehistoric societies is often linked to shifts in the complexity of social structures, because standardized ceramic production can reflect craft specialization and the presence of elite control. Previous work on identifying specialization relies on typological or linear metric analysis. Here we demonstrate how to investigate ceramic standardization by analyzing outlines of ceramic vessels. Outline analysis is useful because, unlike more commonly-used landmark analysis methods, it can effectively quantify shape differences for objects that lack distinctive measurement points needed for landmark analysis. We demonstrate this method using pottery from Kiwulan, a large multi-component Iron Age site (AD 1350-1850) in northeastern Taiwan. To measure ceramic specialization, we quantified pottery standardization by analyzing shape variables with reproducible geometric morphometric methods. We computed coefficients of variation (CVs) for shape coefficients obtained by elliptical Fourier analysis to test for shape standardization. We found significant differences in pottery shape and shape standardization that indicate changes in pottery production resulting from contact with mainland Han Chinese groups in northeastern Taiwan. Our case study, which includes an openly available research compendium of R code, represents an innovative application of outline-based methods in geometric morphometry to answer the anthropological questions of craft specialization.

scholarly journals Arothron: An R package for geometric morphometric methods and virtual anthropology applications

2021 ◽  
Author(s):  
Profico Antonio ◽  
Buzi Costantino ◽  
Castiglione Silvia ◽  
Melchionna Marina ◽  
Piras Paolo ◽  
...  
Keyword(s):  
R Package ◽  
Geometric Morphometric ◽  
Morphometric Methods ◽  
Virtual Anthropology

scholarly journals Comparing skull formation of the Hungarian (Hortobágy) Zackel sheep breed by geometrics morphometrics

2015 ◽  
pp. 29-33
Author(s):  
Zsuzsanna Csóri ◽  
András Gáspárdy ◽  
András Jávor
Keyword(s):  
Morphological Changes ◽  
Time Change ◽  
Carpathian Basin ◽  
Sheep Breed ◽  
Geometric Morphometric ◽  
The Past ◽  
Morphometric Methods ◽  
Skull Formation ◽  
Over Time

This work seeks to explore the morphological changes of the Hungarian (Hortobágy) Zackel sheep's skull, which occurred in the past 50–70 years. In this study, we compared individuals skull forms by geometric morphometric methods. The origin of the breed is not known, we do not know when entering the Carpathian Basin. Therefore, the comparison involved the only known early archaeological findings. We have shown that there is no difference between each period colour variations, but over time change has occurred in the skull formation of the breed.

scholarly journals Geometric Morphometric Analyses Support Incorporating the Goshen Point Type into Plainview

2019 ◽  
Vol 85 (1) ◽  
pp. 171-181 ◽  
Author(s):  
Briggs Buchanan ◽  
Mark Collard ◽  
Michael J. O'Brien
Keyword(s):  
Recent Work ◽  
Social Dynamics ◽  
Spatiotemporal Variation ◽  
Single Type ◽  
Geometric Morphometric ◽  
Morphometric Analyses ◽  
Morphometric Methods ◽  
Point Type

Recent work has demonstrated that Goshen points overlap in time with another group of unfluted lanceolate points from the Plains, Plainview points. This has raised the question of whether the two types should be kept separate or consolidated into a single type. We sought to resolve this issue by applying geometric morphometric methods to a sample of points from well-documented Goshen and Plainview assemblages. We found that their shapes were statistically indistinguishable, which indicates that Goshen and Plainview points should be assigned to the same type. Because Plainview points were recognized before Goshen points, it is the latter type name that should be dropped. Sinking Goshen into Plainview allows us to move beyond taxonomic issues and toward understanding both the spatiotemporal variation that exists among Plainview assemblages and what it can tell us about the adaptations and social dynamics of Plainview groups.

Morphometric variation of fish scales among some species of rattail fish from New Zealand waters

2018 ◽  
Vol 98 (8) ◽  
pp. 1991-1998
Author(s):  
A. L. Ibáñez ◽  
L. A. Jawad
Keyword(s):  
New Zealand ◽  
Discriminant Analysis ◽  
Morphological Evolution ◽  
Procrustes Analysis ◽  
Fish Scales ◽  
Geometric Morphometric ◽  
Morphometric Variation ◽  
Generalized Procrustes Analysis ◽  
Morphometric Methods ◽  
Components Analysis

New Zealand rattail fish are of great interest both to biologists who study their phylogenetics and in fisheries. In contrast, their morphological evolution is little studied and poorly understood. Geometric morphometric methods based on scale shape were applied in this study to determine differences among species and genera. Scale shapes were described using seven landmarks, the coordinates of which were subjected to a generalized Procrustes analysis, followed by a principal components analysis. A cross-validated discriminant analysis was applied to assess and compare the size-shape (centroid size plus shape variables) efficacy in the species and the discrimination of the genera. Two main phenetic groups were identified: cluster no. 1 with eight species and cluster no. 2 with six species. Coelorhinchus aspercephalus and Mesovagus antipodum were more separated from the other species in the first cluster. The cross-validated canonical discriminant analysis correctly classified 74% at the genus level, with most misclassifications occurring between Coelorhinchus and Coryphaenoides, whereas the best classified genera were Mesovagus and Trachyrincus. The discrimination of correctly classified species ranged from 41.2 to 100%. The highest correct classification rates were recorded for Coryphaenoides armatus, Coelorhinchus innotabilis, Trachyrincus longirostris and Mesovagus antipodum.

scholarly journals Heterochronic Shifts Mediate Ecomorphological Convergence in Skull Shape of Microcephalic Sea Snakes

2019 ◽  
Vol 59 (3) ◽  
pp. 616-624 ◽  
Author(s):  
Emma Sherratt ◽  
Kate L Sanders ◽  
Amy Watson ◽  
Mark N Hutchinson ◽  
Michael S Y Lee ◽  
...  
Keyword(s):  
Morphological Changes ◽  
Shape Variation ◽  
Micro Computed Tomography ◽  
Trophic Specialization ◽  
Evolutionary Patterns ◽  
Dietary Specialization ◽  
Geometric Morphometric ◽  
Sea Snakes ◽  
Morphometric Methods ◽  
Cranial Shape

Abstract Morphological variation among the viviparous sea snakes (Hydrophiinae), a clade of fully aquatic elapid snakes, includes an extreme “microcephalic” ecomorph that has a very small head atop a narrow forebody, while the hind body is much thicker (up to three times the forebody girth). Previous research has demonstrated that this morphology has evolved at least nine times as a consequence of dietary specialization on burrowing eels, and has also examined morphological changes to the vertebral column underlying this body shape. The question addressed in this study is what happens to the skull during this extreme evolutionary change? Here we use X-ray micro-computed tomography and geometric morphometric methods to characterize cranial shape variation in 30 species of sea snakes. We investigate ontogenetic and evolutionary patterns of cranial shape diversity to understand whether cranial shape is predicted by dietary specialization, and examine whether cranial shape of microcephalic species may be a result of heterochronic processes. We show that the diminutive cranial size of microcephalic species has a convergent shape that is correlated with trophic specialization to burrowing prey. Furthermore, their cranial shape is predictable for their size and very similar to that of juvenile individuals of closely related but non-microcephalic sea snakes. Our findings suggest that heterochronic changes (resulting in pedomorphosis) have driven cranial shape convergence in response to dietary specializations in sea snakes.

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