Research ArticlePALEONTOLOGY

Gregarious suspension feeding in a modular Ediacaran organism

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Science Advances  19 Jun 2019:
Vol. 5, no. 6, eaaw0260
DOI: 10.1126/sciadv.aaw0260
  • Fig. 1 Study locality.

    (A) Generalized stratigraphic section of Hansburg, Namibia, showing the distribution of Ernietta-bearing units [redrawn from (34)]. Bmt, Basement; Kliphoek mbr, Kliphoek member; Mooif, Mooifontein. (B) Close-up photograph of an overturned slab containing exceptionally preserved Ernietta with detailed suture and individual tube elements. Photo credit: Marc Laflamme, University of Toronto.

  • Fig. 2 CFD results.

    Results of CFD simulations in horizontal (left column) and vertical (right column) cross-sections. All models oriented parallel to flow, at moderate burial depth, and simulations were performed using an inlet velocity of 0.2 m/s. (Top) Single-model simulation results. (Middle) Spaced multiple-model simulation results. (Bottom) Clumped multiple-model simulation results.

  • Fig. 3 CFD results.

    Results of CFD simulations in vertical cross-sections showing vertical velocity (left column) and kinetic energy (right column). All models oriented parallel to flow, at moderate burial depth, and simulations were performed using an inlet velocity of 0.2 m/s. (A and B) Single-model simulation. (C to F) Spaced multiple-model results, where (C) and (D) show left column of individuals and (E) and (F) show right column of individuals with respect to flow. (G to J) Clumped multiple-model results, where (G) and (H) show left column of individuals and (I) and (J) show right column of individuals with respect to flow.

  • Table 1 Drag results.

    Results of CFD simulations for single- and multiple-model simulations of Ernietta, varying the current velocity (0.1, 0.2, and 0.5 m/s), burial depth (shallow, moderate, and deep), and orientation with respect to flow (parallel and perpendicular).

    Density of fluid
    (kg/m3)
    Dynamic viscosity of fluid [kg/(s·m)]
    10000.001
    ModelBurial
    depth
    OrientationCharacteristic
    dimension (m)
    Reference
    area (m2)
    Velocity
    (m/s)
    Reynolds
    number
    Drag force (N)Drag coefficient
    Single individualShallowParallel0.0590.00320.105,9000.011154987172309900.697186698269369
    0.2011,8000.044351560481051200.692993132516425
    0.5029,5000.274513914324550000.686284785811375
    ShallowPerpendicular0.0640.00380.106,4000.016405267277307900.863435119858310
    0.2012,8000.065561319751674600.862648944100981
    0.5032,0000.405470979696828000.853623115151217
    ModerateParallel0.0590.00240.105,9000.007809890114919700.650824176243308
    0.2011,8000.030954507388134100.644885570586127
    0.5029,5000.191483276411148000.638277588037160
    ModeratePerpendicular0.0640.00280.106,4000.010975943502183700.783995964441693
    0.2012,8000.043851773268398200.783067379792825
    0.5032,0000.272179763181450000.777656466232714
    DeepParallel0.0590.00160.105,9000.005102216379739060.637777047467382
    0.2011,8000.020028243222075400.625882600689856
    0.5029,5000.122402450334369000.612012251671845
    DeepPerpendicular0.0640.00180.106,4000.006655689768024390.739521085336043
    0.2012,8000.026597426145657300.738817392934925
    0.5032,0000.164184476809405000.729708785819578
    Four individuals
      Top leftModerateParallel0.0590.00240.2011,8000.03371075116422320.702307315921317
      Bottom leftModerateParallel0.0590.00240.2011,8000.03362495512399880.700519898416642
      Top rightModerateParallel0.0590.00240.2011,8000.00394174691986830.082119727497256
      Bottom rightModerateParallel0.0590.00240.2011,8000.00303755635066140.063282423972112
    Four individuals
      Top leftModeratePerpendicular0.0640.00280.2012,8000.05044362211848450.900778966401509
      Bottom leftModeratePerpendicular0.0640.00280.2012,8000.04913648093919650.877437159628509
      Top rightModeratePerpendicular0.0640.00280.2012,800−0.0008403062351596−0.015005468484993
      Bottom rightModeratePerpendicular0.0640.00280.2012,800−0.0056891902315857−0.101592682706888
    Four individuals
      Top leftModeratePerpendicular0.0640.00280.2012,8000.04987900595373120.890696534888057
      Bottom leftModerateParallel0.0590.00240.2011,8000.03329947150361730.693738989658694
      Top rightModerateParallel0.0590.00240.2011,800−0.0011524043075931−0.024008423074855
      Bottom rightModeratePerpendicular0.0640.00280.2012,8000.00436428749776300.077933705317196
    Four individuals, clumped
      Top leftModerateParallel0.0590.00240.2011,8000.04260601033288620.887625215268462
      Bottom leftModerateParallel0.0590.00240.2011,8000.04261960853208310.887908511085065
      Top rightModerateParallel0.0590.00240.2011,800−0.0074879970079540−0.155999937665708
      Bottom rightModerateParallel0.0590.00240.2011,800−0.0027149188517437−0.056560809411327
    Four individuals, clumped
      Top leftModeratePerpendicular0.0640.00280.2012,8000.05800706142386711.035840382569060
      Bottom leftModeratePerpendicular0.0640.00280.2012,8000.05654830856717461.009791224413830
      Top rightModeratePerpendicular0.0640.00280.2012,800−0.0085171293959361−0.152091596356002
      Bottom rightModeratePerpendicular0.0640.00280.2012,800−0.0084508226386397−0.150907547118565
    Four individuals, clumped
      Top leftModeratePerpendicular0.0640.00280.2012,8000.05805102549587071.036625455283410
      Bottom leftModerateParallel0.0590.00240.2011,8000.04186991753058860.872289948553929
      Top rightModerateParallel0.0590.00240.2011,800−0.0040699100616795−0.084789792951656
      Bottom rightModeratePerpendicular0.0640.00280.2012,800−0.0071175827072387−0.127099691200690
    Five individuals
      Top leftModeratePerpendicular0.0640.00280.2012,8000.04912172296810630.877173624430470
      Bottom leftModerateParallel0.0590.00240.2011,8000.03283103844364750.683979967575990
      Top rightModerateParallel0.0590.00240.2011,8000.02618734151358670.545569614866390
      Middle rightModeratePerpendicular0.0640.00280.2012,8000.01616360123185850.288635736283187
      Bottom rightModerateParallel0.0590.00240.2011,8000.02752102685588870.573354726164348

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/6/eaaw0260/DC1

    Section S1. Reynolds number and drag coefficient calculations for characterizing flow regimes

    Fig. S1. Field photographs of Ernietta aggregations likely representing bioherms.

    Fig. S2. Ernietta model construction for CFD analyses.

    Fig. S3. Select examples of CFD simulation setup.

    Fig. S4. Frontal surface area at respective burial depth for calculations.

    Fig. S5. CFD results for single-individual model.

    Fig. S6. CFD results for multiple-individual model.

    Fig. S7. CFD results for offset multiple-individual model.

    Fig. S8. CFD drag results and SA/V values for all models.

    Table S1. Size measurements of Ernietta from Farm Hansburg and Farm Kuibis in Namibia, collected summer 2016.

    Table S2. Sensitivity analyses for meshing.

    Movie S1. 2D FSI simulation of Ernietta in perpendicular orientation.

    Movie S2. 3D FSI simulation of Ernietta in parallel orientation.

  • Supplementary Materials

    The PDF file includes:

    • Section S1. Reynolds number and drag coefficient calculations for characterizing flow regimes
    • Fig. S1. Field photographs of Ernietta aggregations likely representing bioherms.
    • Fig. S2. Ernietta model construction for CFD analyses.
    • Fig. S3. Select examples of CFD simulation setup.
    • Fig. S4. Frontal surface area at respective burial depth for calculations.
    • Fig. S5. CFD results for single-individual model.
    • Fig. S6. CFD results for multiple-individual model.
    • Fig. S7. CFD results for offset multiple-individual model.
    • Fig. S8. CFD drag results and SA/V values for all models.
    • Table S1. Size measurements of Ernietta from Farm Hansburg and Farm Kuibis in Namibia, collected summer 2016.
    • Table S2. Sensitivity analyses for meshing.
    • Legends for movies S1 and S2

    Download PDF

    Other Supplementary Material for this manuscript includes the following:

    • Movie S1 (.avi format). 2D FSI simulation of Ernietta in perpendicular orientation.
    • Movie S2 (.avi format). 3D FSI simulation of Ernietta in parallel orientation.

    Files in this Data Supplement:

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