Ordovician palaeogeography and climate change

Cocks, L. Robin M.; Torsvik, Trond H.

doi:10.1016/j.gr.2020.09.008

Cited by 142 publications

(80 citation statements)

References 73 publications

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“…13). Many researchers estimate temperatures were close to modern-day, equatorial sea surface temperatures (25-32°C) around low paleo-latitudes (up to 40°N/S) during Late Ordovician time (Trotter et al, 2008;Song et al, 2019;Cocks and Torsvik, 2020). The propensity of Late Ordovician radiolarians to flourish in this range of sea surface temperatures is a characteristic trend shared by other marine clades.…”

Section: Discussionmentioning

confidence: 97%

“…Radiolarians are the only siliceous biomineralizing zooplankton known to have participated in the GOBE. The gradual or sudden increment of the taxonomic richness experienced by marine organisms, including radiolarians, during Early to Middle Ordovician is recognizable in many diversity studies conducted regardless of the region (Stigall et al, 2019;Danelian and Monnet, 2021 (Cocks and Torsvik, 2020). These adjacent terranes account for a majority of Late Ordovician radiolarian occurrences: Malongulli and Ballast formations, Australia (Webby and Blom, 1986;Goto and Ishiga, 1991;Goto et al, 1992;Iwata et al, 1995;Noble and Webby, 2009); Pingliang and Zhaolaoyu formations, North China (Wang, 1993;Song et al, 2000;Wang et al, 2010); Wufeng Formation, South China (Wang and Zhang, 2011;Zhang et al, 2018); and Ulkuntas Horizon, Kazakhstan (Nazarov and Popov, 1980), reported to date.…”

Section: Discussionmentioning

confidence: 99%

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Late Sandbian (Sa2) radiolarians of the Pingliang Formation from the Guanzhuang section, Gansu Province, China

Perera

Aitchison

2021

J. Paleontol.

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A diverse, well-preserved radiolarian assemblage is reported from the Sandbian age Climacograptus bicornis Graptolite Biozone. This new assemblage, recovered from the Pingliang Formation in the Guanzhuang section, China, includes six new species along with 13 other previously described taxa. Geminusphaera new genus incorporates G. grandis n. sp. and G. kongtongensis n. sp. and is proposed for inaniguttids constructed from two distinct porous spheres bearing seven or more primary spines. Protopylentonema new genus is introduced to incorporate pylomate entactinarians with five-rayed initial spicules. It includes P. ordosensis n. sp. as well as P. aperta, P. rimata, and P. insueta that were formerly assigned to Kalimnasphaera. Micro-computed tomography investigation of skeletal microstructure supports establishment of the new genera together with other new spumellarian species: Haplotaeniatum implexa n. sp., Inanigutta quadrispinosa n. sp., and Kalimnasphaera pingliangensis n. sp. It also indicates that family-level reassignment of Etymalbaillella from the Proventocitidae to the Ceratoikiscidae is appropriate. Global distribution of Late Ordovician radiolarian occurrences highlights a strong preference for areas with equatorial to tropical sea surface temperatures. This must have led to ecological stress among radiolarian communities in adapting to global cooling in the Hirnantian. UUID: http://zoobank.org/3d3f55b8-0e70-4f9f-9738-265750d8ec3a.

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Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

Late Sandbian (Sa2) radiolarians of the Pingliang Formation from the Guanzhuang section, Gansu Province, China

Perera

Aitchison

2021

J. Paleontol.

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“…CC BY 4.0 License. was comparatively higher than today (Cocks and Torsvik, 2020). Furthermore, the physical realism of the lycophytes is asserted by constraining certain parameters ranges such as the leaf area (Valdespino, 2015b) or the dry weight of leaves (Leopold et al, 1981) based on literature that includes various taxonomic details of lycophytes.…”

Section: Physiological Strategiesmentioning

confidence: 99%

A dynamic local scale vegetation model for lycophytes (LYCOm)

Halder

Arens

Jensen

et al. 2021

Preprint

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Abstract. Lycophytes (club mosses) represent a distinct lineage of vascular plants with a long evolutionary history including numerous extant and extinct species which started out as herbaceous plants and later evolved into woody plants. They enriched the soil carbon pool through newly developed root-like structures and promoted soil microbial activity by providing organic matter. These plants enhanced soil carbon dioxide (CO2) via root respiration and also modified soil hydrology. These effects had the potential to promote the dissolution of silicate minerals, thus intensifying silicate weathering. The weathering of silicate rocks is considered one of the most significant geochemical regulators of atmospheric CO2 on a long (hundreds of thousands to millions of years) timescale. The motivation for this study is to achieve an increased understanding of the realized impacts of vascular plants, represented by modern relatives to the most basal plants with vascular tissue and shallow root system, on silicate weathering and past climate. To this end, it is necessary to quantify physiological characteristics, spatial distribution, carbon balance, and the hydrological impacts of early lycophytes. These properties, however, cannot be easily derived from proxies such as fossil records, for instance. Hence, as a first step, a process-based model is developed here to estimate net carbon uptake by these organisms at the local scale, considering key features such as biomass distribution above and below ground, root distribution in soil regulating water uptake by plants besides, stomatal regulation of water loss and photosynthesis, and not withholding respiration in roots. The model features ranges of key physiological traits of lycophytes to predict the emerging characteristics of the lycophyte community under any given climate by implicitly simulating the process of selection. In this way, also extinct plant communities can be represented. In addition to physiological properties, the model also simulates weathering rates using a simple limit-based approach and estimates the biotic enhancement of weathering by lycophytes. We run the Lycophyte model, called LYCOm, at seven sites encompassing various climate zones under today’s climatic conditions. LYCOm is able to simulate realistic properties of lycophyte communities at the respective locations and estimates values of Net Primary Production (NPP) ranging from 126 g carbon m−2 year−1 to 245 g carbon m−2 year−1. Our limit-based weathering model predicts a mean chemical weathering rate ranging from 5.3 to 45.1 cm ka−1 rock with lycophytes varying between different sites, as opposed to 0.6–8.3 cm rock ka−1 without lycophytes, thereby highlighting the potential importance of such vegetation at the local scale for enhancing chemical weathering. Our modeling study establishes a basis for assessing biotic enhancement of weathering by lycophytes at the global scale and also for the geological past. Although our method is associated with limitations and uncertainties, it represents a novel, complementary approach towards estimating the impacts of lycophytes on biogeochemistry and climate.

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“…The Rubisco kinetic limits are adjusted from Galmes et al (2014). This is done keeping in mind that the current model serves as a basis for paleoclimate (Ordovician) simulations when the lycophytes appeared and the mean surface temperature was comparatively higher than today (Cocks and Torsvik, 2020). Furthermore, the physical realism of the lycophytes is asserted by constraining certain parameters ranges such as the leaf area (Valdespino, 2015b) or the dry weight of leaves (Leopold et al, 1981) based on literature that includes various taxonomic details of lycophytes.…”

Section: Physiological Strategiesmentioning

confidence: 99%

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Halder

2021

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Ordovician palaeogeography and climate change

Cited by 142 publications

References 73 publications

Late Sandbian (Sa2) radiolarians of the Pingliang Formation from the Guanzhuang section, Gansu Province, China

Late Sandbian (Sa2) radiolarians of the Pingliang Formation from the Guanzhuang section, Gansu Province, China

A dynamic local scale vegetation model for lycophytes (LYCOm)

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