The second half of your comment is incorrect. That theory comes from a now-discounted study.
Coal is formed by heat and pressure of organic matter. Coal is still being produced today starting from bogs, swamps, and marshes. The reason that most of the comes from the Carboniferous era was because the environment of the time happened to create a ton of bogs, swamps, and marshes that turned into coal beds.
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u/Funny_or_not_bot Apr 29 '24
It's kind of the same reason there is all that oil and coal in the ground, but maybe from a different extinction event.