Using X-ray computed tomography analysis tools to compare the skeletal element morphology of fossil and modern frog (Anura) species

Matthews, Thalassa; Plessis, Anton du

doi:10.26879/557

Cited by 12 publications

(10 citation statements)

References 26 publications

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“…While whole-surface algorithms were developed originally for human faces, it can be applied to any type of surface data where there is a natural correspondence. Regarding full-surface long bone data, they have been studied within comparative anatomy [21], biomedicine [22–24] and forensic anthropology (to match paired elements) [25]. …”

Section: Introductionmentioning

confidence: 99%

Sexual Dimorphism of the Human Tibia through Time: Insights into Shape Variation Using a Surface-Based Approach

et al. 2016

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In this paper we present a three-dimensional (3D) morphometrical assessment of human tibia sexual dimorphism based on whole bone digital representation. To detect shape–size and shape differences between sexes, we used geometric morphometric tools and colour-coded surface deviation maps. The surface-based methodology enabled analysis of sexually dimorphic features throughout the shaft and articular ends of the tibia. The overall study dataset consisted of 183 3D models of adult tibiae from three Czech population subsets, dating to the early medieval (9–10th century) (N = 65), early 20th century (N = 61) and 21st-century (N = 57). The time gap between the chronologically most distant and contemporary datasets was more than 1200 years. The results showed that, in all three datasets, sexual dimorphism was pronounced. There were some sex-dimorphic characteristics common to all three samples, such as tuberosity protrusion, anteriorly bowed shaft and relatively larger articular ends in males. Diachronic comparisons also revealed substantial shape variation related to the most dimorphic area. Male/female distinctions showed a consistent temporal trend regarding the location of dimorphic areas (shifting distally with time), while the maximal deviation between male and female digitized surfaces fluctuated and reached the lowest level in the 21st-century sample. Sex determination on a whole-surface basis yielded the lowest return of correct sex assignment in the 20th-century group, which represented the lowest socioeconomic status. The temporal variation could be attributed to changes in living conditions, the decreasing lower limb loading/labour division in the last 12 centuries having the greatest effect. Overall, the results showed that a surface-based approach is successful for analysing complex long bone geometry.

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Section: Introductionmentioning

confidence: 99%

Sexual Dimorphism of the Human Tibia through Time: Insights into Shape Variation Using a Surface-Based Approach

et al. 2016

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“…crocodilian brain; Witmer et al, 2008), and can be used to assess and quantify differences between extinct and extant taxa (e.g. Dollion et al, 2015;Matthews and du Plessis, 2016). Nevertheless, the technique might not be suitable for all fossils, because successful acquisition of data is limited mainly by the size of the object and density of the surrounding matrix.…”

Section: Palaeobiologymentioning

confidence: 99%

X-ray microtomography in herpetological research: a review

Broeckhoven

Plessis

2018

Amphib.-Reptilia

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Herpetological research, like any other (palaeo)biological science, relies heavily on accurate data collection, particularly visualisation and quantification of anatomical features. While several high-resolution imaging methods are currently available, one technique in particular, x-ray microtomography or micro-computed tomography, is on the verge of revolutionising our understanding of the morphology of amphibians and reptiles. Here, we present a review on the prevalence and trends of x-ray microtomography in herpetological studies carried out over the last two decades. We describe its current use, provide practical guidelines for future research that focusses on the morphological study of reptiles and amphibians, and highlight emerging trends including soft-tissue and in vivo scanning. Furthermore, while x-ray microtomography is a rapidly evolving field with great potential, various important drawbacks are associated with its use, including sample size effect and measurement errors resulting from differences in spatial resolution and preparation techniques. By providing recommendations to overcome these hurdles, we ultimately aim to maximise the benefits of x-ray microtomography to herpetological research.

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“…After viewing a number of slice images to ensure the selection was done properly, the air was removed. Similarly, each seed is then selected to include its internal air volumes (Matthews and du Plessis 2016). None of this is required for a basic viewing of slice images in a typical non-destructive analysis viewing but for 3D analysis and quantitative volume measurements as reported here.…”

Section: Experiments 1: Time Of Fertilisationmentioning

confidence: 99%

Microcomputer tomography (microCT) as a tool in Pinus tree breeding: pilot studies

Ham

Plessis

Roux

2017

N.Z. j. of For. Sci.

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Background: Pinus breeding programmes yield high numbers of seeds, but a non-destructive method to determine seed viability is still lacking. With the long reproductive cycle (up to 28 months) of Pinus species, determining when fertilisation occurs can assist when applying tissue culture methods like somatic embryogenesis (SE). For SE, pre-cotyledonary zygotic embryos are ideal for culture initiation (some weeks after fertilisation), while mature zygotic embryos are extracted and used for in vitro amplification during organogenesis. Achieving automated viability assays in extracted seeds would also be helpful, as would being able to find numbers and condition of seeds in immature or unopened cones. For such applications, microcomputer tomography (microCT) was a candidate technology. MicroCT was used to scan immature cones of Pinus radiata D.Don at four-weekly intervals after pollination to determine time of fertilisation. After harvesting of mature cones, a sample of 30 seeds of each of three Pinus species (P. radiata, P. patula Schiede ex Schltdl. & Cham. and P. pinaster Aiton) were scanned together in one microCT scan, and the same seed was allowed to germinate on moist filter paper after scanning. In addition, a mature unopened cone of P. radiata was also microCT-scanned to determine the potential for determining seed viability in situ, and the seed was subsequently extracted for examination. Findings: Fertilisation evidently occurred between weeks 64 and 68 after pollination in P. radiata. The microCT data for extracted seeds of the three species identified some seeds with large voids, which suggest nonviability (low to zero germination potential), and that was confirmed by the germination test. In addition to demonstrating in situ seed viability in the unopened P. radiata cone, the seed extraction revealed that some non-viable seeds remained trapped in the basal part of the dried cone. Conclusions: This case study demonstrates the feasibility of using microCT scans as a partially non-destructive method in Pinus tree breeding programmes to confirm fertilisation and determine seed viability. However, scanning the seed after extraction from mature cones can help to determine viability which is often hard to gauge from seeds' external appearance. Future studies need to narrow the time window of fertilisation by scanning a wider variety of genotypes between weeks 64 and 68 after pollination.

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Using X-ray computed tomography analysis tools to compare the skeletal element morphology of fossil and modern frog (Anura) species

Cited by 12 publications

References 26 publications

Sexual Dimorphism of the Human Tibia through Time: Insights into Shape Variation Using a Surface-Based Approach

Sexual Dimorphism of the Human Tibia through Time: Insights into Shape Variation Using a Surface-Based Approach

X-ray microtomography in herpetological research: a review

Microcomputer tomography (microCT) as a tool in Pinus tree breeding: pilot studies

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