Cox, A;
Pates, S;
(2024)
Geographic, taxonomic, and temporal interrogation of bradoriid diversity and carapace disparity.
Palaeontologia Electronica
, 27
(3)
, Article 27.3.a56. 10.26879/1424.
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Abstract
Bradoriids are an abundant order of extinct marine arthropods that ranged from the early Cambrian to the mid-Ordovician, with a global distribution. The bivalved carapace of bradoriids varies in size, shape and ornamentation. This study presents the first quantitative analysis of bradoriid morphological disparity, quantifying the outline shape of carapaces with respect to a range of variables. Elliptical Fourier analysis (EFA) was used to quantify the carapace outline shape of 139 specimens, representing 128 species, from material figured in the literature. The mean bradoriids carapace was postplete. Families broadly overlapped in the morphospace, with Beyrichonidae the most disparate. Similarly, bradoriids from different continents mostly overlap in the morphospace, with Avalonian bradoriids occupying the most extreme positions. Bradoriid disparity changed through time, peaking at Stage 4. However, the reductions in disparity following extinction events represents a ‘thinning’ rather than culling of particular morphologies, showing that extinctions were not selective for particular bradoriids carapace shapes. Centroid position does show a shift in the morphospace over time, representing a change in mean valve shape from postplete to amplete, however, this is likely due to retention of extreme forms and lower diversity in younger samples. Pelagic bradoriids display similar carapace outlines to benthic ones. Our results are likely impacted by the overrepresentation of bradoriids from early Cambrian deposits and uneven geographic sampling. Studying the morphological variation of bradoriid carapace shape can provide context for understanding patterns in their distribution, species longevity, and their demise in the late Cambrian.
| Type: | Article |
|---|---|
| Title: | Geographic, taxonomic, and temporal interrogation of bradoriid diversity and carapace disparity |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.26879/1424 |
| Publisher version: | https://doi.org/10.26879/1424 |
| Language: | English |
| Additional information: | This work is licensed under a Creative Commons License. The images or other third-party material in this article are included in the Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ |
| Keywords: | Bradoriida; Cambrian; Ordovician; morphospace; Elliptical Fourier Analysis |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10208526 |
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