Professor Nevin Kozik, PhD, of Department of Earth, Ocean and Atmospheric Science – National High Magnetic Field Laboratory, Florida State University, during fieldwork to investigate how rapid changes in marine oxygen levels may have played a significant role in driving Earth’s first mass extinction.
Fundamental to the Theory of Evolution (TOE) is the idea that environmental change causes evolutionary change, a consequence of which can be extinction, especially when change is too rapid for species to evolve adaptations to it. Environmental change can be very rapid (instantaneous in the case of a meteor strike, for example) but evolutionary change is characteristically very slow, needing many generations to produce a significant adaptation.
So, it's hardly surprising that a period of rapidly fluctuating marine oxygen levels about 443 million years ago, caused Earth's first mass extinction at the same time. Confirmation of that, and so of a prediction of the TOE, has now been produced by a team led by Florida State University (FSU) researchers.
The research depends on a fairly recent dating method for marine sediment that measures the proportion of thallium isotopes in the sediment, as explained by Owens, J.D; Neilson S.D; Horner, T.J., et al (2016)[PDF]:
AbstractOne of the team who discovered that dating method, Associate professor Jeremy D Owens, PhD. now at FSU, was involved in this study by the FSU team.
Thallium (Tl) isotopes are a new and potentially powerful paleoredox proxy that may track bottom water oxygen conditions based on the global burial flux of manganese oxides. Thallium has a residence time of ~20 thousand years, which is longer than the ocean mixing time, and it has been inferred that modern oxic seawater is conservative with respect to both concentration and isotopes. Marine sources of Tl have nearly identical isotopic values. Therefore, the Tl sinks, adsorption onto manganese oxides and low temperature oceanic crust alteration (the dominant seawater output), are the primary controls of the seawater isotopic composition. For relatively short-term, ~million years, redox events it is reasonable to assume that the dominant mechanism that alters the Tl isotopic composition of seawater is associated with manganese oxide burial because large variability in low temperature ocean crust alteration is controlled by long-term, multi-million years, average ocean crust production rates…
As the Florida State University news release explains:
About 443 million years ago, life on Earth was undergoing the Late Ordovician mass extinction, or LOME, which eliminated about 85% of marine species. Scientists have long studied this mass extinction and continue to investigate its possible causes, such as reduced habitat loss in a rapidly cooling world or persistent low-oxygen conditions in the oceans.
By measuring isotopes of the element thallium — which shows special sensitivity to changes in oxygen in the ancient marine environment — the research team found that previously documented patterns of this mass extinction coincided with an initial rapid decrease in marine oxygen levels followed by a rapid increase in oxygen. Their work is published online in the journal Science Advances.
That decrease in oxygen was immediately followed by an increase. This rapid shift in oxygen coincided with the traditional first die-off of mass extinction and major ice sheet growth over the ancient South Pole.Paleontologists have noted that there were several groups of organisms, such as graptolites and brachiopods, that started to decline very early in this mass extinction interval, but we didn’t really have any good evidence of an environmental or climate signature to tie that early decline of these groups to a particular mechanism. This paper can directly link that early phase of extinction to changes in oxygen. We see a marked change in thallium isotopes at the same time these organisms start their steady decline into the main phase of the mass extinction event.
Turbulence in oxygen levels in oceanic waters is really what seems to have been pretty problematic for organisms that were living in the Late Ordovician at that time, which might have been adapted to cope with low oxygen conditions initially or vice versa. The fact that oxygen levels in the oceans next to the continents switching back and forth over short geologic time scales (a few hundred thousand years) really did seem to play havoc with these marine ecosystems.
Professor Seth Young, co-author.
Department of Earth, Ocean and Atmospheric Science – National High Magnetic Field Laboratory
Florida State University, Tallahassee, FL, USA.
The Late Ordovician extinction was one of five major mass extinctions in Earth’s history and the only one scientists are confident took place in what are called “icehouse” conditions, in which widespread ice sheets are present on Earth’s surface. Earth is currently experiencing icehouse conditions and loss of biodiversity, which makes this ancient mass extinction an important analog for present-day conditions, along with trying to understand Earth’s future as our climate continues to warm and ice sheets recede.
The discovery of the initial expansion of low-oxygen conditions on a global level and the coincidence with the early phases of decline in marine animals helps paint a clearer picture of what was happening with this extinction event.
Professor Nevin Kozik, lead author.
Department of Earth, Ocean and Atmospheric Science – National High Magnetic Field Laboratory
Florida State University, Tallahassee, FL, USA.
Previous research into environmental conditions surrounding the LOME used evidence found in limestones from more oxygenated settings, but this study used shales that were deposited in deeper, oxygen-poor water, which record different geochemical signatures, allowing the researchers to make conclusions about global marine conditions, rather than for local conditions. Co-authors on this paper were doctoral student Sean Newby and associate professor Jeremy Owens of FSU; former FSU postdoctoral scholar and current assistant professor at the College of Charleston Theodore Them; Mu Liu and Daizhao Chen of the Chinese Academy of Sciences; Emma Hammarlund of Lund University; and David Bond of the University of Hull.
Copyright: © 2022 The authors.Published by American Association for the Advancement of Science.
Open access. (CC BY 4.0)
AbstractSo, what the researchers found was a correlation between these close periods of rappidly changing oxygen levels in sea water and the extinction of very many species. In other words, just as the TOE predicts, rapid environmental changes can be too quick for species to adapt by the relatively slow process of evolution by small steps over time.
The timing and connections between global cooling, marine redox conditions, and biotic turnover are underconstrained for the Late Ordovician. The second most severe mass extinction occurred at the end of the Ordovician period, resulting in ~85% loss of marine species between two extinction pulses. As the only “Big 5” extinction that occurred during icehouse conditions, this interval is an important modern analog to constrain environmental feedbacks. We present a previously unexplored thallium isotope records from two paleobasins that record global marine redox conditions and document two distinct and rapid excursions suggesting vacillating (de)oxygenation. The strong temporal link between these perturbations and extinctions highlights the possibility that dynamic marine oxygen fluctuations, rather than persistent, stable global anoxia, played a major role in driving the extinction. This evidence for rapid oxygen changes leading to mass extinction has important implications for modern deoxygenation and biodiversity declines.
Kozik, Nevin P.; Young, Seth A.; Newby, Sean M.; Liu, Mu; Chen, Daizhao; Hammarlund, Emma U.; Bond, David P. G.; Them, Theodore R.; Owens, Jeremy D.
Rapid marine oxygen variability: Driver of the Late Ordovician mass extinction
Science Advances 2022; 8(46), eabn8345. DOI: 10.1126/sciadv.abn8345
Published by American Association for the Advancement of Science. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)
Yet another instance where the TOE is fully capable of explaining the geological record without recourse to god-magic or supernatural intervention by unproven magical entities such as those required by the childish, evidence-free notion of Creationism.
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