On the importance of examining the relationship between shape data and biologically meaningful variables. An example studying allometry with geometric morphometrics

Marugán‐Lobón, Jesús; Chamero, Beatriz; Martín‐Abad, Hugo

doi:10.7203/sjp.28.2.17848

Cited by 7 publications

(10 citation statements)

References 36 publications

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“…Importantly, the power of GM increases when aiming to test the statistical covariation of shape with possibly related factors (Bookstein, 1991), yet this has seldom been exploited by any biological or paleontological discipline, in spite of its immense potential to aid discovery (Monteiro, 1999;Marugán-Lobón et al, 2013). Here we have shown that bipedal dinosaur trackways not only can be easily compared statistically and graphically using 2D GM, but also that the observed variation across trackways can be factored out to gain further insight.…”

Section: Discussionmentioning

confidence: 98%

“…We also tested if the trackway shape differences and the estimated speed differences are statistically associated with size (i.e., size is the real scale of the trackway) using multivariate and bivariate linear regressions (Monteiro, 1999;Marugán-Lobón et al, 2013), respectively. These tests are a rough proxy to asking if trackway geometry and movement speed are related to the size of the producing dinosaur.…”

Section: Methodsmentioning

confidence: 99%

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Studying bipedal dinosaur trackways using geometric morphometrics

Costa-Pérez

Moratalla

Marugán‐Lobón

2019

Palaeontol Electron

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Traditionally, the study of dinosaur tracks and trackways has been helpful to learn about the anatomy of the trackmaker and its biodynamics. The implementation of digital techniques has further allowed delving into elusive evidence, such as the nature of autopod-substrate interaction and to build virtual collections. However, new methods that help to discriminate more objectively traits that lurk undetected within the tracks and the trackways are needed. Geometric Morphometrics (GM) is one of such advanced tools for shape analysis, but it has only been used for the comparison and ichnotaxonomic assessment of isolated footprints, and never for the study of dinosaur trackways. Using 2D GM, we analysed the differences between 75 randomly selected trackways of bipedal dinosaurs from literature, and tested if their variation was associated to the sizes of the trackways and to the estimated speeds at which the latter moved when leaving the trackways. Our results show that the method easily summarizes most of the trackway geometric differences, showing that such variation relates to footprint relative sizes, their orientation and their relative positions within the trackway. Importantly, the multivariate statistics indicated that none such differences could be attributed to ichnotaxa, while they clearly correlated with size, and in a much larger degree, to the estimated speeds at which the trackways were laid. Moreover, size and speed are unrelated, entailing that much of the trackway differences involve the biodynamics of bipedal dinosaurs, irrespective of their trackmaker assignment, plus substrate dynamics.

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Section: Discussionmentioning

confidence: 98%

Section: Methodsmentioning

confidence: 99%

Studying bipedal dinosaur trackways using geometric morphometrics

Costa-Pérez

Moratalla

Marugán‐Lobón

2019

Palaeontol Electron

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“…In addition, they found in their study that at the peak of the adolescent growth spurt, skeletal development was more advanced in females compared to males, but that at the end of the spurt, females had a less mature skeletal development than males [30]. The assumption that the appropriate measurement of size is the size of the anatomical structure analysed, usually evaluated as the centroid size of a landmark configuration, is encountered in many morphometric analyses [10][11][12]16]. Centroid size is a composite measure of size based on all the landmarks and is proportional to the square root of the summed square interlandmark distances.…”

Section: Discussionmentioning

confidence: 99%

“…CS is a scalar accounting for the actual distance (in the actual scale of each specimen) between the landmarks and the centroid of the configuration (the geodesic centre of the configuration). The most common measure of size utilised in GM is centroid size (CS), which is the square root of the summed square distances between all the landmarks and their centroid [8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

“…For the majority of anatomical structures, proportions and shapes have a regular relationship with size. Many genetic and environmental factors are effective on growth and it is important to understand the extent of allometric variability [10][11][12][13][14][15][16]. In our study, deformation related to age or developmental stage was evaluated for the hand and wrist using the geometric morphometric method.…”

Section: Introductionmentioning

confidence: 99%

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Statistical shape analysis of hand and wrist in paediatric population on radiographs

Koç¹,

Ercan²,

Ozdemir³

et al. 2020

Turk J Med Sci

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Background/aim: The goal of this study was to compare differences in hand and wrist shapes and to evaluate these according to growth and allometry in children on radiographs related to bone age. Materials and methods: The study included 263 males and 189 females. A total of 452 left hand and wrist radiographs were retrospectively collected. Standard anatomical landmarks marked on radiographs. Results: There were seen to be significant differences in comparisons of hand and wrist shapes according to sex (P = 0.009). The most suitable model in the growth models was seen as the Gompertz growth model for both females and males (model P < 0.001). For the relationship between shape and size to evaluate allometry, significant models were obtained in females (model P = 0.017, MSE = 0.0002) and in males (model P < 0.001, MSE = 0.0002). In our study, the difference between the sexes was found mostly in the radiocarpal region. It was observed that the deformation of the carpal bones started in the distal row carpal bones. Conclusion: Significant differences were found in hand and wrist shapes according to sex. Models for growth and allometry of hand and wrist shapes were found to be significant in children.

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Chicken HOXC8 and HOXC10 genes may play a role in the altered skull morphology associated with the Crest phenotype

Tsai

Chen

et al. 2023

J Exp Zool Pt B

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One of the most intriguing traits found in domestic chickens is the Crest phenotype. This trait, characterized by a tuft of elongated feathers sprouted from the head, is found in breeds such as Polish chickens and Silkie chickens. Moreover, some crested chicken breeds also exhibit a protuberance in their anterodorsal skull region. Previous studies have strived to identify the causative factors of this trait. This study aimed to elucidate the role of chicken HOXC8 and HOXC10 in the formation of the Crest phenotype. We explored the effect of ectopic expression of HOXC8 or HOXC10 on the chicken craniofacial morphology using the RCAS retrovirus transformation system. Microcomputed tomography scanning was conducted to measure the 3D structure of the cranial bone of transgenic embryos for geometric morphometric analysis. We found that the ectopic expression of HOXC8 or HOXC10 in chicken heads caused mild morphological changes in the skull compared with the GFP‐transgenic control group. Geometric morphometric analysis showed that HOXC8 and HOXC10 transgenic groups expressed a mild upward shape change in the frontal region of the skull compared with the control group, which is similar to what is seen in the crested chicken breeds. In conclusion, this study supports findings in previous studies in which HOX genes play a role in the formation of the altered skull morphology related to the Crest phenotype. It also supports that mutations in HOX genes may contribute to intra‐ and inter‐specific variation in morphological traits in vertebrates.

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On the importance of examining the relationship between shape data and biologically meaningful variables. An example studying allometry with geometric morphometrics

Cited by 7 publications

References 36 publications

Studying bipedal dinosaur trackways using geometric morphometrics

Studying bipedal dinosaur trackways using geometric morphometrics

Statistical shape analysis of hand and wrist in paediatric population on radiographs

Chicken HOXC8 and HOXC10 genes may play a role in the altered skull morphology associated with the Crest phenotype

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