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RE: Paleontology and Dinosaurology 101: What layperson MUST to know about?



> -----Original Message-----
> From: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu] 
> On Behalf Of David Marjanovic
> Sent: Monday, February 07, 2011 8:13 AM
> To: DML
> Subject: 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"!

"Brown" was supposed to be shorthand for "heterokonts", to include the diatoms. 
Technically not brown, of course.

And while there is a shift at the P/Tr, it is by no means complete. It is only 
with the great diversification of coccolithophorids
and diatoms during the Jurassic and Cretaceous that the oceans really "redden":

Martin, R.E., A. Quigg, & V. Podkovyrov. 2008 Marine biodiversification in 
response to evolving phytoplankton stoichiometry,
Palaeogeography, Palaeoclimatology, Palaeoecology 258:277-291 DOI: 
10.1016/j.palaeo.2007.11.003.
(http://www.sciencedirect.com/science/article/B6V6R-4R53WN5-4/2/ea8a61e7da455da0984c25dd97724b79)

Thomas R. Holtz, Jr.
Email: tholtz@umd.edu   Phone: 301-405-4084
Office: Centreville 1216                        
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
http://www.geol.umd.edu/~tholtz/
Fax: 301-314-9661               

Faculty Director, Science & Global Change Program, College Park Scholars
http://www.geol.umd.edu/sgc
Fax: 301-314-9843

Mailing Address:        Thomas R. Holtz, Jr.
                        Department of Geology
                        Building 237, Room 1117
                        University of Maryland
                        College Park, MD 20742 USA