There were land-based life forms a billion years ago …
Here’s David Tyler at Access Research Network (05/31/11), on “Non-marine life throughout the Neoproterozic”:
What do these findings mean for our understanding of life on the Precambrian Earth? Dr Charles Wellman, an author of the paper, is quoted by ScienceDaily as saying:
“It is generally considered that life originated in the ocean and that the important developments in the early evolution of life took place in the marine environment: the origin of prokaryotes, eukaryotes, sex and multicellularity. During this time the continents are often considered to have been essentially barren of life — or at the most with an insignificant microbial biota dominated by cyanobacteria. We have discovered evidence for complex life on land from 1 billion year old deposits from Scotland. This suggests that life on land at this time was more abundant and complex than anticipated. It also opens the intriguing possibility that some of the major events in the early history of life may have taken place on land and not entirely within the marine realm.” Read More ›