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Re: Paleontology and Dinosaurology 101: What layperson MUST to know about?
"What does a layperson HAVE TO know about?"
* During the Jurassic and (especially) the Cretaceous, a major
transformation of marine life occurred. Green-algae phytoplankton
were displaced by red- and brown-algae (which continue to dominate
modern marine ecosystems).
I thought this change from "green oceans" to "red oceans" happened at
the P-Tr boundary mass extinction?
BTW, there are no planktonic brown algae (Phaeophyta), they're all
multicellular and benthic. However, some of their fellow chromists
(eukaryotes with a red alga as an endosymbiont) are planktonic and
brown, such as the pelagophytes that make brown tides today.
Not literally brown planktonic chromists include the haptophytes, to
which the coccolithophores belong. Chalk only forms in "red oceans"!