Fungi are being credited with allowing or at least supporting the rise of plants on land. These giant fungi were the first large land organisms known. 

 

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420 million years ago, a giant feasted on the dead, growing slowly into the largest living thing on land. It belonged to an unlikely group of pioneers that ultimately made life on land possible -- the fungi. 
 

 

Great vid! It is part of the PBS Eons series. I had not seen this particular one before or encountered this idea. Very interesting.