Bivalve body size distribution through the Late Triassic mass extinction event
- 1. Institute of Ecology and Biodiversity*
- 2. Natural History Museum
Description
The synergic relationship between physiology, ecology and evolutionary process makes the body size distribution (BSD) an essential component of the community ecology. Body size is highly susceptible to environmental change, and extreme upheavals, such as during a mass extinction event, could exert drastic changes on a taxon's BSD. It has been hypothesized that the Late Triassic mass extinction event (LTE) was triggered by intense global warming, linked to massive volcanic activity associated with the Central Atlantic Magmatic Province. We test the effects of the LTE on the BSD of fossil bivalve assemblages from three study sites spanning the Triassic/Jurassic boundary in the UK. Our results show that the effects of the LTE were rapid and synchronous across sites, and the BSDs of the bivalves record drastic changes associated with species turnover. No phylogenetic signal of size selectivity was recorded, although semi-infaunal species were apparently most susceptible to change. Each size class had the same likelihood of extinction during the LTE, which resulted in a platykurtic BSD with negative skew. The immediate post-extinction assemblage exhibits a leptokurtic BSD although with negatively skewed, where surviving species and newly appearing small-sized colonizers exhibit body sizes near the modal size. Recovery was relatively rapid (~100kyr), and larger bivalves began to appear during the Pre-Planorbis Zone, despite recurrent dysoxic/anoxic conditions. This study demonstrates how a mass extinction acts across the size spectrum in bivalves and shows how BSDs emerge from evolutionary and ecological processes.
Notes
Supplementary information contains: Dataset.Body.Size.Opazo&Twitchett2021.csv_Paleobiology contains one spreadsheet with all body size measurements used in this study. This file is made up of 17 columns which indicates:
- Formation = Corresponds to stratigraphic units (and biozones) considered in this study: WF: Westbury Formation/ CM: Cotham Member/ LM: Langport Member/ PPZ=Pre-Planorbis Zone/ PZ=Planorbis Zone/ LZ: Liasicus Zone/ AZ: Angulata Zone
- Locality = NI: Larne, Northern Ireland/PB: Pinhay Bay, Devon/AB: St. Audrie's Bay (all from United Kingdom)
- Sample = Sample Code
- Heights (m) = Stratigraphic height
- Tier = Infaunal/Surficial/Semi-infaunal
- Taxonomy=Order/Family/Genus/Species
Ecological categories: Colonizers/Extinct/Survivors Length (mm) = Maximum distance on the anterior–posterior axis
- Height (mm) = Maximum distance on the dorsal-ventral axis
- BS (mm) = Body size expressed as geometric mean (i.e., the square root of the product of length and width)
- log2 (BS) = log2 of the geometric mean
- Residuals = Grand bivalves mean (log2) minus the body size (log2) of each specimen
- Lithology = Mudstone/Limestone
Opazo&Twitchett2021.Supplementary.text.pdf_Paleobiology: This file contains information regarding paleoenvironment, extinction event and the Triassic/Jurassic Boundary, and geological setting of the Triassic/Jurassic Boundary in the United Kingdom. Additionally, this file contains the R code to generate a null model completely random.
1. Opazo&Twitchett2021.Supplementary.figures.pdf_Paleobiology
2. Opazo&Twitchett2021.Supplementary.tables.pdf_Paleobiology
Funding provided by: Alβan Programme (the European Union Programme of High Level Scholarships for Latin America)*
Crossref Funder Registry ID:
Award Number: E07D402767CL
Funding provided by: CONICYT - Beca de Doctorado en el Extranjero por Gestión Propia*
Crossref Funder Registry ID:
Award Number: 2007
Funding provided by: Postdoctoral CONICYT*
Crossref Funder Registry ID:
Award Number: 2013
Funding provided by: Postdoctoral FONDECYT*
Crossref Funder Registry ID:
Award Number: 3160191
Files
Opazo_Twitchett2021.Supplementary.figures.pdf
Additional details
Related works
- Is derived from
- 10.5061/dryad.3xsj3txhc (DOI)