This is a fossil fern that I found in Russellville AR and its from the Pennsylvanian, an era within the Carboniferous, which was about 300 million years ago, rounded off of course. I believe it to be a neuropteris fern.
History is riddled with massive die-offs. At times, of Earth& species disappeared. Here& a look at the worst extinction events and what caused them.
A not-terrible breakdown of 5 of Earth's most Catastrophic mass extinction events
The stingray Heliobatis radians provides remarkable detail, from the very fine disc and fin bones to the deadly tail barb. The four fossil fish that surround it (Knightia eocaena), are also exceptional in preservation and composition.
Earth’s Worst Mass Murderers: Oxygen, Volcanoes… And Humans? Mass-Extinctions Infographic, World Science Festival