original_query: What explanation did Fedonkin propose for the appearance of biomineralization around the start of the Cambrian?
query: What explanation did Mikhail A. Fedonkin propose for the appearance of biomineralization around the start of the Cambrian?
answer: Fedonkin suggested that the Ediacara biota evolved and flourished in cold waters, which slowed their metabolisms and left them with insufficient spare energy for biomineralization; but there are signs of global warming around the start of the Cambrian, which would have made biomineralization easier.  A similar pattern is visible in living marine animals, since biomineralized skeletons are rarer and more fragile in polar waters than in the tropics.