Analysis of shape data: From landmarks to elastic curves

AbstractCrown birds are subdivided into two main groups, Palaeognathae and Neognathae, that can be distinguished, among others, by the organization of the bones in their pterygoid-palatine complex (PPC). Shape variation to the vomer, which is the most anterior part of the PPC, was recently analysed by Hu et al. (2019) with help of geometric morphometrics to discover morphological differences between palaeognath and neognath birds. Based on this study, the vomer was identified as sufficient to distinguish the two main groups (and even more inclusive neognath groups) and their cranial kinetic system. As there are notable size differences between the skulls of palaeognaths and neognaths, we here investigate the impact of allometry on vomeral shape and its implication for taxonomic classification by re-analysing the data of the previous study. Different types of multivariate statistical analyses reveal that taxonomic identification based on vomeral shape is strongly impaired by allometry, as the error of correct identification is high when shape data is corrected for size. This finding is evident by a great overlap between palaeognath and neognath subclades in morphospace. The correct identification is further influenced by the convergent presence of a flattened vomeral morphotype in multiple neognath subclades. As the evolution of cranial kinesis has been linked to vomeral shape in the original study, the existing correlation between shape and size of the vomer across different bird groups found in the present study questions this conclusion. In fact, cranial kinesis in crown birds results from the loss of the jugal-postorbital bar in the temporal region and ectopterygoid in the PPC and the combination of a mobilized quadrate-zygomatic arch complex and a flexible PPC. Therefore, we can conclude that the vomer itself is not a suitable proxy for exploring the evolution of cranial kinesis in crown birds and their ancestors.

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Curve straightening and a minimax argument for closed elastic curves

Topology ◽

10.1016/0040-9383(85)90046-1 ◽

1985 ◽

Vol 24 (1) ◽

pp. 75-88 ◽

Cited By ~ 31

Author(s):

Joel Langer ◽

David A. Singer

Keyword(s):

Elastic Curves

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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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Average Q and yield estimates from the Pahute Mesa test site

Bulletin of the Seismological Society of America ◽

10.1785/bssa0770041274 ◽

1987 ◽

Vol 77 (4) ◽

pp. 1274-1294

Author(s):

R. W. Burger ◽

T. Lay ◽

L. J. Burdick

Keyword(s):

Time Domain ◽

Near Field ◽

Energy Levels ◽

Source Model ◽

Spectral Shape ◽

Field Amplitude ◽

Far Field ◽

Source Models ◽

Attenuation Models ◽

Shape Data

Abstract Attenuation models, with and without frequency dependence, have been developed through analysis of time-domain amplitude measurements and teleseismic spectral shape data from Pahute Mesa nuclear explosions. The time-domain analysis is based on a near-field to far-field amplitude comparison. The near-field amplitude information is incorporated in two parameterized explosion source models (Mueller-Murphy and Helmberger-Hadley) based on analyses of near-field data. The teleseismic amplitude observations are from a large data set of WWSSN short-period analog recordings. For the narrow-band time-domain data, the various source and attenuation models are indistinguishable. We utilize the spectral shape data in the 0.5- to 4-Hz band as a constraint on the source-attenuation models at higher frequencies, concluding that either source model, when convolved with the appropriate frequency-dependent Q model, can be consistent with both the near-field and far-field time-domain amplitudes and the spectral shape data. Given the trade-off between source and attenuation models and the similarity of the different source models in the 0.5- to 4-Hz band, it is difficult to prefer clearly one source model over the other. The Mueller-Murphy model is more consistent with surface wave amplitude measurements because of larger predicted long-period energy levels. Whether or not frequency dependence is included in the attenuation model, the value of t* near 1 Hz is about 1.0 sec (assuming the Mueller-Murphy source model) or 0.8 sec (assuming the Helmberger-Hadley source model). This 0.2 sec difference results from greater 1-Hz energy levels for the Mueller-Murphy source model. Adopting an average attenuation model, predicted amplitudes and yields are shown to be within the uncertainty of the data for all the events analyzed.

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Combining Shape Data and Traditional Measurements with the 2B-PLS: Testing the Covariation Between Avian Brain Size and Cranial Shape Variation as an Example

Morphometrics for Nonmorphometricians - Lecture Notes in Earth Sciences ◽

10.1007/978-3-540-95853-6_7 ◽

2010 ◽

pp. 179-190 ◽

Cited By ~ 2

Author(s):

Jesús Marugán-Lobón

Keyword(s):

Brain Size ◽

Avian Brain ◽

Shape Variation ◽

Shape Data ◽

Cranial Shape

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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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