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I spent two days observing the coast of half moon bay along a 2 mile stretch of land. I made this because if it is true, it would place an extinction event between 2 recorded ones.

I recall not too long ago there was a pretty interesting scientific article published in the Journal Science describing how scientists analyzed the amount and diversity of chondrichthyan denticles in ichthyoliths from the North and South Pacific dating from around 20-19 million years ago and discovered a sharp drop in the number and diversity of denticles around 19 million years ago, indicating a massive extinction took place which took sharks 2 to 5 million years to somewhat recover from (it's still unknown if this impacted chondrichthyans worldwide or just in the pacific). Here's the paper: https://www.science.org/doi/10.1126/science.aaz3549 E. C. Sibert, L. D. Rubin, An early Miocene extinction in pelagic sharks. Science 372, 1105–1107 (2021). But after reading it, I remembered how the Mississippian and somewhat Pennsylvanian periods of the Carboniferous era have been called the golden age of sharks due to the sheer diversity of chondrichthyan genera alive at that time. http://www.elasmo-research.org/education/evolution/golden_age.htm What I'm wondering is does this paper, in revealing this early miocene extinction event, inadvertently also reveal that the period immediately prior to the event was a second "golden age" for the chondrichthyans?