On the morphospace of eurypterine sea scorpions

Earth and Environmental Science Transactions of the Royal Society of Edinburgh ◽

10.1017/s175569102100030x ◽

2021 ◽

pp. 1-6

Author(s):

Russell D. C. BICKNELL ◽

Lisa AMATI

Keyword(s):

New Taxa ◽

Compound Eye ◽

Developmental Changes ◽

Apex Predators ◽

Geometric Morphometric ◽

Eye Morphology ◽

Morphometric Analyses ◽

Ontogenetic Trajectories ◽

Landmark Analyses ◽

Shape Data

ABSTRACT Eurypterids (sea scorpions) are a group of extinct, marine euchelicerates that have an extensive Palaeozoic record. Despite lacking a biomineralised exoskeleton, eurypterids are abundantly preserved within select deposits. These collections make statistical analyses comparing the morphology of different genera possible. However, eurypterid shape has not yet been documented with modern geometric morphometric tools. Here, we summarise the previous statistical assessments of eurypterid morphology and expand this research by presenting landmark and semi-landmark analyses of 115 eurypterid specimens within the suborder Eurypterina. We illustrate that lateral compound eye morphology and position drives specimen placement in morphospace and separates proposed apex predators from more generalist forms. Additionally, evidence for size clusters in Eurypterus that may reflect ontogeny is uncovered. We highlight the use of geometric morphometric analyses in supporting the naming of new taxa and demonstrate that these shape data represent a novel means of understanding inter-generic ontogenetic trajectories and uncovering developmental changes within the diverse euarthropod group.

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Tissue preservation can affect geometric morphometric analyses: a case study using fish body shape

Zoological Journal of the Linnean Society ◽

10.1093/zoolinnean/zlz069 ◽

2019 ◽

Vol 188 (1) ◽

pp. 148-162 ◽

Cited By ~ 5

Author(s):

Carmelo Fruciano ◽

Dominik Schmidt ◽

Marcia Maria Ramírez Sanchez ◽

Witold Morek ◽

Zamira Avila Valle ◽

...

Keyword(s):

Body Shape ◽

Canonical Variate ◽

Shape Variation ◽

Substantial Variation ◽

Geometric Morphometric ◽

Fresh Fish ◽

Morphometric Analyses ◽

Variate Analysis ◽

Shape Data

Abstract In geometric morphometrics, the extent of variation attributable to non-biological causes (i.e. measurement error) is sometimes overlooked. The effects of this variation on downstream statistical analyses are also largely unknown. In particular, it is unclear whether specimen preservation induces substantial variation in shape and whether such variation affects downstream statistical inference. Using a combination of empirical fish body shape data and realistic simulations, we show that preservation introduces substantial artefactual variation and significant non-random error (i.e. bias). Most changes in shape occur when fresh fish are frozen and thawed, whereas a smaller change in shape is observed when frozen and thawed fish are fixed in formalin and transferred to ethanol. Surprisingly, we also show that, in our case, preservation produces only minor effects on three downstream analyses of shape variation: classification using canonical variate analysis, permutation tests of differences in means and computations of differences in mean shape between groups. Even mixing of differently preserved specimens has a relatively small effect on downstream analyses. However, we suggest that mixing fish with different preservation should still be avoided and discuss the conditions in which this practice might be justified.

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A Newly Noticed Formula Enforces Fundamental Limits on Geometric Morphometric Analyses

Evolutionary Biology ◽

10.1007/s11692-017-9424-9 ◽

2017 ◽

Vol 44 (4) ◽

pp. 522-541 ◽

Cited By ~ 24

Author(s):

Fred L. Bookstein

Keyword(s):

Geometric Morphometric ◽

Fundamental Limits ◽

Morphometric Analyses

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Compaction-related deformation in Cambrian olenelloid trilobites and its implications for fossil morphometry

Journal of Paleontology ◽

10.1017/s0022336000027827 ◽

1999 ◽

Vol 73 (2) ◽

pp. 355-371 ◽

Cited By ~ 40

Author(s):

Mark Webster ◽

Nigel C. Hughes

Keyword(s):

Lower Cambrian ◽

Shape Change ◽

Anterior Lobe ◽

Interspecific Differences ◽

Fracture Patterns ◽

Morphometric Analyses ◽

Ontogenetic Trajectories ◽

Metric Distances ◽

Relative Convexity ◽

Shape Changes

Morphometric analyses of silicified and nonsilicified (preserved in shale) specimens of the olenelloid trilobites Olenellus (Olenellus) gilberti Meek (in White, 1874) and Nephrolenellus geniculatus Palmer, 1998, from the Lower Cambrian C-Shale Member of the Pioche Formation show that even well-preserved specimens in shales have undergone significant changes in lateral as well as vertical dimensions as a result of compaction. Analyses of cephalic landmarks show that in both species compaction causes posteriordirected collapse of the anterior lobe of the glabella, adaxial deformation of the ocular lobes, and abaxial and anterior splaying of genal regions. These shape changes are explicable in terms of observed exoskeletal fracture patterns. Landmarks show an increase in scatter around their ontogenetic trajectories that is generally proportional to the degree of lateral shift each landmark has undergone. Interspecific differences in compactional response may depend on the relative convexity of the cephalon. Olenellus (Olenellus) gilberti is a low-convexity species and shows marked lateral shape change, particularly in the genal region. Nephrolenellus geniculatus is more convex and shows less severe lateral shape change. Landmarks of both species exhibit an average trebling of the degree of scatter around their average ontogenetic trajectories in compacted samples. Because even well-preserved specimens in shales differ in shape from their precompactional appearance, results of morphometric studies utilizing metric distances between landmarks in trilobites where compaction can be detected must be interpreted with caution.

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Morphological diversity in tenrecs (Afrosoricida, Tenrecidae): comparing tenrec skull diversity to their closest relatives

10.7287/peerj.preprints.811v1 ◽

2015 ◽

Author(s):

Sive Finlay ◽

Natalie Cooper

Keyword(s):

Quantitative Analysis ◽

Quantitative Methods ◽

Morphological Diversity ◽

Lateral View ◽

Ecological Niches ◽

Diverse Group ◽

Geometric Morphometric ◽

Skull Shape ◽

Morphometric Analyses ◽

The Family

Morphological diversity is often studied qualitatively. However, to truly understand the evolution of exceptional diversity, it is important to take a quantitative approach instead of relying on subjective, qualitative assessments. Here, we present a quantitative analysis of morphological diversity in a Family of small mammals, the tenrecs (Afrosoricida, Tenrecidae). Tenrecs are often cited as an example of an exceptionally morphologically diverse group. However, this assumption has not been tested quantitatively. We use geometric morphometric analyses of skull shape to test whether tenrecs are more morphologically diverse than their closest relatives, the golden moles (Afrosoricida, Chrysochloridae). Tenrecs occupy a wider range of ecological niches than golden moles so we predict that they will be more morphologically diverse. Contrary to our expectations, We find that tenrec skulls are only more morphologically diverse than golden moles when measured in lateral view. Furthermore, similarities among the species-rich Microgale tenrec Genus appear to mask higher morphological diversity in the rest of the Family. These results reveal new insights into the morphological diversity of tenrecs and highlight the importance of using quantitative methods to test qualitative assumptions about patterns of morphological diversity.

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Wing morphometry as a tool for correct identification of primary and secondary New World screwworm fly

Bulletin of Entomological Research ◽

10.1017/s0007485309006762 ◽

2009 ◽

Vol 100 (1) ◽

pp. 19-26 ◽

Cited By ~ 14

Author(s):

M.L. Lyra ◽

L.M. Hatadani ◽

A.M.L. de Azeredo-Espin ◽

L.B. Klaczko

Keyword(s):

Population Variation ◽

Canonical Variate ◽

Correct Identification ◽

Morphological Marker ◽

Geometric Morphometric ◽

Control Programs ◽

Cochliomyia Macellaria ◽

Males And Females ◽

Cattle Breeders ◽

Shape Data

AbstractCochliomyia hominivoraxandCochliomyia macellariaare endemic Neotropical Calliphoridae species. The former causes severe myiasis in hosts while the latter is Sarcosaprophagous, but commonly found as a second invader in wounds. Due to the morphological similarity between them and the potential losses thatC. hominivoraxrepresents for cattle breeders, the rapid and correct identification of these two species is very important. In addition to a correct identification of these species, a good knowledge ofC. hominivoraxbiology can be helpful for designing control programs. We applied geometric morphometric methods to assess wing differences betweenC. hominivoraxandC. macellariaand conduct a preliminary analysis of wing morphological variation inC. hominivoraxpopulations. Canonical variate analysis, using wing shape data, correctly classified 100% of the individuals analyzed according to sex and species. This result demonstrates that wing morphometry is a simple and reliable method for identifyingC. hominivoraxandC. macellariasamples and can be used to monitorC. hominivorax. Both species show sexual dimorphism, but inC. hominivoraxit is magnified. We suggest that this may reflect different histories of selection pressures operating on males and females. Significant differences in wing size and shape were obtained amongC. hominivoraxpopulations, with little correlation with latitude. This result suggests that wing variation is also a good morphological marker for studying population variation inC. hominivorax.

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Geometric Morphometric Analyses Support Incorporating the Goshen Point Type into Plainview

American Antiquity ◽

10.1017/aaq.2019.89 ◽

2019 ◽

Vol 85 (1) ◽

pp. 171-181 ◽

Cited By ~ 1

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.

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Do island populations differ in size and shape compared to mainland counterparts?

Journal of Mammalogy ◽

10.1093/jmammal/gyz193 ◽

2019 ◽

Vol 101 (2) ◽

pp. 373-385 ◽

Cited By ~ 2

Author(s):

Sergio Ticul Álvarez-Castañeda ◽

Laura A Nájera-Cortazar

Keyword(s):

Geometric Morphometric ◽

Island Populations ◽

Terrestrial Vertebrates ◽

Skull Shape ◽

Skull Size ◽

Morphometric Analyses ◽

Interpopulation Variation ◽

Pocket Mouse ◽

Shape Analyses ◽

Insular Populations

Abstract Adaptation and evolution of terrestrial vertebrates inhabiting islands have been the topic of many studies, particularly those seeking to identify trends or patterns in body size in mammals, albeit not necessarily in shape, in relation to mainland populations. The spiny pocket mouse, Chaetodipus spinatus, is distributed in the Baja California peninsula and its surrounding islands. Insular populations became isolated ~12,000 due to changes in sea level; these populations’ matrilinear (mitochondrial) DNA shows minor interpopulation variation. We tested the hypothesis that adaptation and evolution in these island populations involve variation in both skull size and skull shape (using geometric morphometrics) relative to mainland populations, rather than only in size as previously assumed. A total of 363 specimens from 15 insular and peninsular populations were used in analysis of the skull length and geometric morphometric analyses. Our findings revealed significant differences related to skull size among population. The skull shape analyses showed two significantly different morphotypes: one for all island specimens and one for all mainland samples. Our analyses support the hypothesis that insular populations may not only vary in size relative to mainland populations, but may also show variations in shape, regardless of differing conditions across islands.

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