Analysis of chemical signatures embedded within ancient geological strata suggests a protracted decline in marine ecosystem health predating the catastrophic extinction event that decimated numerous species approximately 201 million years ago, near the close of the Triassic period.
Early Earth. Image credit: Peter Sawyer / Smithsonian Institution.
“The terminal Triassic period is characterized by one of the most profound mass extinction episodes in Earth’s history, the end-Triassic mass extinction, which transpired just preceding the Triassic-Jurassic geological boundary (201 million years ago),” stated Virginia Tech geologist Kayla McCabe and her research associates.
“This significant event led to an estimated 60% attrition of marine invertebrates at the generic level and was contemporaneous with numerous shifts in paleoenvironmental conditions.”
“It has been posited that extensive volcanic activity originating from the Central Atlantic magmatic province was the impetus behind the environmental transformations that precipitated the end-Triassic mass extinction.”
“These transformations encompassed phenomena such as global warming, ocean acidification, and oxygen depletion, among other adverse effects.”
In their recent scientific inquiry, McCabe and her fellow researchers directed their attention to the preserved geological record.
Between the years 2017, 2019, and 2022, their expeditions brought them to Grotto Creek, situated within Alaska’s Wrangell-St. Elias National Park, a remote locale accessible solely via small aircraft.
At this site, they conducted a comparative study of sedimentary rock formations laid down in the epochs preceding, during, and following the extinction event.
These stratigraphical layers meticulously document the environmental circumstances that prevailed in the ancient Panthalassan Ocean.
A temporal retrospective through these geological layers indicates that dissolved oxygen concentrations in shallow oceanic waters began a decline approximately eight million years prior to the culmination of the end-Triassic mass extinction.
This incipient reduction in oxygen likely exerted considerable stress on marine biological communities well in advance of the primary extinction phase.
Geochemical investigations reveal that the depletion of oxygen escalated in severity during the extinction period itself, emerging as a principal contributing factor to the widespread loss of species.
Benggwigwishingasuchus eremicarminis on the Panthalassan Ocean coast. Image credit: Jorge Gonzalez.
“There exists evidence pertaining to another volcanic province whose temporal occurrence roughly aligns with this period,” commented Virginia Tech geochemist Ben Gill.
“However, we are presently at the nascent stages of comprehending the full scope of these events.”
“While the ultimate cause may still be elusive, we have established a clear understanding of the sequence of phenomena.”
“Consequently, this provides us with a foundational framework for anticipating future events, given that our present-day oceans are concurrently experiencing acidification and deoxygenation, phenomena also observable in regions such as the Chesapeake Bay.”
“The planet has previously undergone analogous scenarios. We possess empirical data confirming that climatic warming precedes a cascade of subsequent environmental repercussions.”
“This historical precedent offers valuable insights into potential future outcomes.”
The results of this investigation have been formally published in the esteemed journal Nature Communications Earth & Environment.
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K.E. McCabe et al. 2026. Deoxygenation in the equatorial Panthalassan Ocean predated the end-Triassic mass extinction. Commun Earth Environ 7, 460; doi: 10.1038/s43247-026-03362-w
