According to a study just published in Nature, “Complex life left the oceans earlier than thought” and “The eukaryotes spent more time evolving on land” (Jennifer Welsh, MSNBC, 4/13/2011):
These freshwater eukaryotes probably came from their oceanic brethren, but the fossil record for these microorganisms is so spotty, it’s hard to tell, Strother told LiveScience. Strother’s team is continuing to sort through samples of microfossils for more examples of the types of complex life that lived at this time.[ … ]
They also likely had sex — reproduced by mixing their genomes together, which most eukaryotes do — and many might have created their own energy from the sun. “In some cases they are going to be displacing things that are already there and in other cases they would be adding a tier to what already existed,” Strother told LiveScience.
[ … ]
“We know very little about life in non-marine realms. Strother and colleagues have demonstrated that eukaryote microbes had colonized and flourished in lacustrine (lake) and other non-marine ecosystems,” Shuhai Xiao, a researcher not involved in the study from Virginia Polytechnic Institute and State University, told LiveScience in an email. “This is not trivial, as biological activities in non-marine ecosystems would have had important impact on global biogeochemical cycles.”
Note: Everything seems to be happening “earlier than thought” or “more suddenly than thought,” which leads to the question, why is it “thought” to be slow and late? Why not just assume that it is quick and early?