The evolution and initial rise of pelagic caryocaridids in the Ordovician

Liu, Yilong; Fan, Ruo-ying; Zong, Ruiwen; Gong, Yiming

doi:10.1016/j.earscirev.2022.104097

Cited by 8 publications

(7 citation statements)

References 120 publications

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“…The homogenization of the Fezouata Shale Formation can be partially explained by examining the changes in the lifestyles of the trilobites in our dataset (Chatterton and Speyer 1989; Speyer and Chatterton 1989; Signor and Vermeij 1994; Hughes et al 2006; Fortey 2014; Laibl et al 2023), given the known colonization of the nektonic and planktonic realm by many animal groups throughout the late Cambrian and Early Ordovician (Servais et al 2010; Liu et al 2022). We find that 37% of the trilobite genera recovered from the subassemblages of the lower Fezouata Shale Formation belong to families known to have planktonic postembryonic larval stages (e.g., Asaphidae, Calymenidae, Nileidae), whereas 47% of the trilobite genera recovered from the upper Fezouata Shale Formation belong to families known to have planktonic postembryonic larval stages (e.g., Asaphidae, Calymenidae, Raphiophoridae).…”

Section: Discussionmentioning

confidence: 99%

The Fezouata Shale Formation biota is typical for the high latitudes of the Early Ordovician—a quantitative approach

Richards,

Nanglu,

Ortega-Hernández

2024

Paleobiology

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The Fezouata Shale Formation has dramatically impacted our understanding of Early Ordovician marine ecosystems before the great Ordovician biodiversification event (GOBE), thanks to the abundance and quality of exceptionally preserved animals within it. Systematic work has noted that the shelly fossil subassemblages of the Fezouata Shale biota are typical of open-marine deposits from the Lower Ordovician, but no studies have tested the quantitative validity of this statement. We extracted 491 occurrences of recalcitrant fossil genera from the Paleobiology Database to reconstruct 31 subassemblages to explore the paleoecology of the Fezouata Shale and other contemporary, high-latitude (66°S–90°S) deposits from the Lower Ordovician (485.4–470 Ma) and test the interpretation that the Fezouata Shale biota is typical for an Ordovician open-marine environment. Sørensen's dissimilarity metrics and Wilcoxon tests indicate that the subassemblages of the Tremadocian-aged lower Fezouata Shale are approximately 20% more heterogenous than the Floian-aged upper Fezouata Shale. Dissimilarity metrics and visualization suggest that while the lower Fezouata and upper Fezouata share faunal components, the two sections have distinct faunas. We find that the faunal composition of the lower Fezouata Shale is comparable with other Tremadocian-aged subassemblages from high latitudes, suggesting that it is typical for an Early Ordovician open-marine environment. We also find differences in faunal composition between Tremadocian- and Floian-aged deposits. Our results corroborate previous field-based and qualitative systematic studies that concluded that the shelly assemblages of the Fezouata Shale are comparable with those of other Lower Ordovician deposits from high latitudes. This establishes the first quantitative baseline for examining the composition and variability within the assemblages of the Fezouata Shale and will be key to future studies attempting to discern the degree to which it can inform our understanding of marine ecosystems just before the start of the GOBE.

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Section: Discussionmentioning

confidence: 99%

The Fezouata Shale Formation biota is typical for the high latitudes of the Early Ordovician—a quantitative approach

Richards,

Nanglu,

Ortega-Hernández

2024

Paleobiology

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“…silicula are smaller, c. 10-15 mm [25]. Caryocaridids are generally between 10-30 mm in length [21].…”

Section: Plos Onementioning

confidence: 99%

“…Sixteen taxa were chosen, sampled from terminals in the phylogenetic analysis of Liu et al [21]. Taxa were chosen ensuring a broad range across the phylogeny, including at least one representative from all clades of at least two taxa and at least one representative of each genus (Fig 1).…”

Section: Taxonomic Samplingmentioning

confidence: 99%

“…Two dimensional outlines of 15 species of Ordovician and one late Cambrian archaoestracans were generated from reconstructions in the literature (14 from Ref [21], and one each from Refs [24,27]) using Inkscape 1.0. For the literature source and figure used for each outline, see the OSF project [28].…”

Section: Carapace Outlinesmentioning

confidence: 99%

“…Ordovician macroscopic pelagic arthropods (size range 20-200 mm) [1] include trilobites [18,19] and caryocaridid archaeostracans [20,21]. The morphological characteristics and cosmopolitan distribution of caryocaridids, including their carapace shape and common presence in outer shelf or slope settings alongside graptolites in black shales, supports a pelagic life mode at the fringes of continental margins for this group [20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

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Hydrodynamic performance of Ordovician archaeostracan carapaces

Pates,

Xue

2024

PLoS ONE

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The diversification of macroscopic pelagic arthropods such as caryocaridid archaeostracans was a crucial aspect of the Great Ordovician Biodiversification Event, and the plankton revolution. A pelagic mode of life has been inferred for caryocaridids from their common presence in black graptolitic shales alongside carapace morphologies that appear streamlined. However, the hydrodynamic performance within the group and comparisons with other archaeostracans were lacking. Here we use a computational fluid dynamics approach to quantify the hydrodynamic performance of caryocaridids, and other early Palaeozoic archaeostracans including Arenosicaris inflata and Ordovician ceratiocaridids. We show that streamlining of the carapace was an important factor facilitating a pelagic mode of life in caryocaridids, in reducing the drag coefficient and facilitating a broader range of lift coefficients at different angles of attack. However, comparable hydrodynamic performance is also recovered for some ceratiocaridids. This suggests that alongside carapace streamlining, adaptations to appendages and thinning of the carapace were also important for a pelagic mode of life in Ordovician caryocaridids.

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