aries, there were 13 with increases exceeding 50%, and 11 of those more than doubled (columns D and E, Table 1). There were also 15 such %NLSSS increases, and 7 of those more than doubled (columns G and H, Table 1). Seven boundaries show NLSSS decreases of 50% or more over the previous boundary (column D, Table 1), and eleven show %NLSSS decreases of 50% or more (column G, Table 1). Considering total decreases, even over multiple boundaries, 8 NLSSS decreases exceeded 50% (columns D and E, Table 1) and 12 %NLSSS decreases exceeded 50%. Thus, even when NLSSS data is normalized to the number of species in the preceding stage—e.g., as %NLSSS data—the rises and drops in NLSSS data are substantial. As indicated above, substantial changes in NLSSS and %NLSSS values suggest non-uniformity of process. Investigation of these data in the Flood sediments may provide insight into pre-Flood biozonation and/or Flood processes that can separate organisms and/or preserve pre-Flood organismal associations. 3. NLSSS data and biostratigraphic units and events We have argued that NLSSS data divides the earth’s stratigraphic column into five global, biostratigraphic units. The earth’s stratigraphic column has been divided into other global biostratigraphic units for a very long time—many of them for more than a century. How do these biostratigraphic units compare to the NLSSS biostratigraphic units? At the coarsest scale, the Phanerozoic is divided into the Paleozoic, Mesozoic, and Cenozoic erathems. The last two correspond rather closely with the Mesozoic and Cenozoic NLSSS zones. The Paleozoic erathem might correspond to the ‘marine’ biozone of the Flood if (1) further study of the Paleozoic-Cambrian zone reassigns the Cambrian as part of the ‘marine’ biozone of the Flood and (2) taking out the floating forest organisms also unites the Pennsylvanian-Permian NLSSS zone to the ‘marine’ biozone of the Flood. If so, then (roughly speaking) the Cenozoic erathem and NLSSS zone are both post-Flood, the Mesozoic erathem and NLSSS zone are the ‘terrestrial’ biozone of the Flood, the Paleozoic erathem and NLSSS zone are the ‘marine’ biozone of the Flood, and the Precambrian would be pre-Flood. Erathems, then, may well be evidenced in NLSSS data. However, none of the biostratigraphic divisions of the erathems down to the level of stages (e.g., series and/or systems) are evidenced in NLSSS data. We see nothing in the NLSSS or %NLSSS data (columns C or F, Table 1) that seems to consistently match any of the system or series boundaries (far right column, Table 1). Lyell created the first divisions of the Cenozoic based on the percent living mollusk species, but almost all biostratigraphic divisions of the erathems have, since then, been defined with respect to ‘index fossils’. Index fossils are geographically widespread taxa (optimally global) that are restricted to one narrow zone of the stratigraphic column. The lack of correlation between NLSSS data and any biostratigraphic zones between the stage and the erathem, suggests ‘index fossils’ might carry no special signature other than their very particular biostratigraphic position. ‘Mass extinctions’ are not biostratigraphic units. But, ‘mass extinctions’ are positions in the global biostratigraphic column where a large percentage of taxa below that position are never seen above that position. In principle, the disappearance of many taxa across a boundary would imply a change in organismal composition from one stratigraphic unit to the next. If enough taxa disappeared, this would result in a biostratigraphic boundary. The more global the disappearance, the more global will be the biostratigraphic boundary. One would then expect ‘mass extinctions’ to be found at biostratigraphic boundaries, and the largest ‘mass extinctions’ at the coarsest biostratigraphic boundaries. One would also expect sudden drops in number of taxa to correspond to very low NLSSS values. Since ‘mass extinctions’ are nothing more than higher than ‘normal’ ‘extinction rate,’ they are arbitrarily defined. There is no consensus on what is a ‘higher than normal’ extinction rate. There is also no consensus on how to measure the relative size of different ‘mass extinction’ events. However, column I in Table 1 lists the twelve most substantial ‘mass extinctions’ according to a roughly estimated rank (with ‘1’ exhibiting the highest ‘extinction rate’). As we might expect, the 1st- and 3rdranked ‘mass extinctions’ do correspond to the boundaries between the three erathems and the upper three NLSSS biostratigraphic zones (comparing C, I, and far right columns, Table 1). The 1st-ranked ‘mass extinction’ also corresponds to the largest percentage drop in %NLSSS values (column G, Table 1). The 2nd-, 4th-, and 5th-ranked ‘mass extinctions’ do correspond to system boundaries, but the relationship between ‘mass extinctions’ and biostratigraphic boundaries blurs after that. Most of the ‘mass extinctions’ are at or near drops in NLSSS values, but there does not seem to be a relationship between the ranking of ‘mass extinctions’ and the percentage drop in %NLSSS values (columns F versus I, Table 1). ‘Mass extinctions,’ then, like NLSSS values, do not seem to strongly support the system and series divisions of the erathems. 4. Megasequences and biostratigraphic data Sloss’s (1964) North American megasequences can be documented globally (e.g., Clarey and Werner 2018). The last of Sloss’s ‘megasequences’—the Tejas—is not bound above by an unconformity, nor is it characterized by fining upward clastics topped by a carbonate, nor are its distinct lithologies typically traceable across continents. The other five (the Sauk, the Tippecanoe, the Kaskaskia, the Absaroka, and the Zuni) are megasequences sensu stricto (unconformity-bound sequences of continent-wide, fining upward clastics, topped with continent-wide carbonate). Each megasequence sensu stricto suggests an enormous global surge in water energy followed by diminution of energy. And, since each one of them left sediments in the interior of continents, they each appear to be global inundations indicative of the Flood. Alone, these five megasequences suggest the Flood ran from the Tonian/Cryogenian boundary (boundary 13) to the Danian/Selandian boundary (boundary 94). This is consistent with the Flood boundaries derived from NLSSS data (somewhere between boundary 8 and 25 to boundary 94). Beyond the overall beginning and ending of the Flood, however, there does not seem to be any correlation between megasequences sensu stricto and either the NLSSS data or the biostratigraphic divisions of the stratigraphic column. We see no connection between the beginnings, the peaks, or the terminations of the five megasequences sensu stricto (column J, Table 1) and either NLSSS or %NLSSS data (columns C and F, Table 1). Nor do these megasequence features seem to bear any relationship to divisions of the biostratigraphic column (far right column, Table 1). Nor do these megasequence features seem to bear relationship to ‘mass extinction’ events (column J, TaWISE and RICHARDSON Biostratigraphic continuity and earth history 2023 ICC 622
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