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Increased atmospheric SO₂ detected from changes in leaf physiognomy across the Triassic-Jurassic boundary interval of East Greenland.
PLoS One. 2013; 8(4):e60614.Plos

Abstract

The Triassic-Jurassic boundary (Tr-J; ∼201 Ma) is marked by a doubling in the concentration of atmospheric CO2, rising temperatures, and ecosystem instability. This appears to have been driven by a major perturbation in the global carbon cycle due to massive volcanism in the Central Atlantic Magmatic Province. It is hypothesized that this volcanism also likely delivered sulphur dioxide (SO2) to the atmosphere. The role that SO2 may have played in leading to ecosystem instability at the time has not received much attention. To date, little direct evidence has been presented from the fossil record capable of implicating SO2 as a cause of plant extinctions at this time. In order to address this, we performed a physiognomic leaf analysis on well-preserved fossil leaves, including Ginkgoales, bennettites, and conifers from nine plant beds that span the Tr-J boundary at Astartekløft, East Greenland. The physiognomic responses of fossil taxa were compared to the leaf size and shape variations observed in nearest living equivalent taxa exposed to simulated palaeoatmospheric treatments in controlled environment chambers. The modern taxa showed a statistically significant increase in leaf roundness when fumigated with SO2. A similar increase in leaf roundness was also observed in the Tr-J fossil taxa immediately prior to a sudden decrease in their relative abundances at Astartekløft. This research reveals that increases in atmospheric SO2 can likely be traced in the fossil record by analyzing physiognomic changes in fossil leaves. A pattern of relative abundance decline following increased leaf roundness for all six fossil taxa investigated supports the hypothesis that SO2 had a significant role in Tr-J plant extinctions. This finding highlights that the role of SO2 in plant biodiversity declines across other major geological boundaries coinciding with global scale volcanism should be further explored using leaf physiognomy.

Authors+Show Affiliations

School of Biology and Environmental Science, University College Dublin, Belfield, Dublin, Ireland. karenl.bacon@gmail.comNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

23593262

Citation

Bacon, Karen L., et al. "Increased Atmospheric SO₂ Detected From Changes in Leaf Physiognomy Across the Triassic-Jurassic Boundary Interval of East Greenland." PloS One, vol. 8, no. 4, 2013, pp. e60614.
Bacon KL, Belcher CM, Haworth M, et al. Increased atmospheric SO₂ detected from changes in leaf physiognomy across the Triassic-Jurassic boundary interval of East Greenland. PLoS ONE. 2013;8(4):e60614.
Bacon, K. L., Belcher, C. M., Haworth, M., & McElwain, J. C. (2013). Increased atmospheric SO₂ detected from changes in leaf physiognomy across the Triassic-Jurassic boundary interval of East Greenland. PloS One, 8(4), e60614. https://doi.org/10.1371/journal.pone.0060614
Bacon KL, et al. Increased Atmospheric SO₂ Detected From Changes in Leaf Physiognomy Across the Triassic-Jurassic Boundary Interval of East Greenland. PLoS ONE. 2013;8(4):e60614. PubMed PMID: 23593262.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Increased atmospheric SO₂ detected from changes in leaf physiognomy across the Triassic-Jurassic boundary interval of East Greenland. AU - Bacon,Karen L, AU - Belcher,Claire M, AU - Haworth,Matthew, AU - McElwain,Jennifer C, Y1 - 2013/04/10/ PY - 2012/12/29/received PY - 2013/02/28/accepted PY - 2013/4/18/entrez PY - 2013/4/18/pubmed PY - 2013/10/25/medline SP - e60614 EP - e60614 JF - PloS one JO - PLoS ONE VL - 8 IS - 4 N2 - The Triassic-Jurassic boundary (Tr-J; ∼201 Ma) is marked by a doubling in the concentration of atmospheric CO2, rising temperatures, and ecosystem instability. This appears to have been driven by a major perturbation in the global carbon cycle due to massive volcanism in the Central Atlantic Magmatic Province. It is hypothesized that this volcanism also likely delivered sulphur dioxide (SO2) to the atmosphere. The role that SO2 may have played in leading to ecosystem instability at the time has not received much attention. To date, little direct evidence has been presented from the fossil record capable of implicating SO2 as a cause of plant extinctions at this time. In order to address this, we performed a physiognomic leaf analysis on well-preserved fossil leaves, including Ginkgoales, bennettites, and conifers from nine plant beds that span the Tr-J boundary at Astartekløft, East Greenland. The physiognomic responses of fossil taxa were compared to the leaf size and shape variations observed in nearest living equivalent taxa exposed to simulated palaeoatmospheric treatments in controlled environment chambers. The modern taxa showed a statistically significant increase in leaf roundness when fumigated with SO2. A similar increase in leaf roundness was also observed in the Tr-J fossil taxa immediately prior to a sudden decrease in their relative abundances at Astartekløft. This research reveals that increases in atmospheric SO2 can likely be traced in the fossil record by analyzing physiognomic changes in fossil leaves. A pattern of relative abundance decline following increased leaf roundness for all six fossil taxa investigated supports the hypothesis that SO2 had a significant role in Tr-J plant extinctions. This finding highlights that the role of SO2 in plant biodiversity declines across other major geological boundaries coinciding with global scale volcanism should be further explored using leaf physiognomy. SN - 1932-6203 UR - https://www.unboundmedicine.com/medline/citation/23593262/Increased_atmospheric_SO₂_detected_from_changes_in_leaf_physiognomy_across_the_Triassic_Jurassic_boundary_interval_of_East_Greenland_ L2 - http://dx.plos.org/10.1371/journal.pone.0060614 DB - PRIME DP - Unbound Medicine ER -