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Kyle Chlavin
Section: M012
EAR 117 Recitation: Assignment #6
This article by Wanyi Lu was a very interesting read and actually took me two times to
fully understand what this article was talking about. After the second read, I finally realized what
he was talking about. In my opinion, the most interesting part of the article was towards the end
when Lu discusses how the rise of oxygen levels over time in the ocean is linked to the increase
in animal body size. Before reading this article, I always assumed that evolution and survival of
the fittest was the main reason animals changed in size throughout time. I was partially right, but
a lot of the gaps were still missing until reading this article. Yes, evolution does play a big part
but there is more involved than what the eye can see through iodine to calcium ratios in marine
carbonates. Through research of marine animals during the Phanerozoic time period, it shows
that biovolume most likely correlated with iodine and calcium which indicates that O2 in the
upper ocean was prevalent and an important factor in the evolution in the Phanerozoic metazoan
evolution (Figure 3B of article). Because of this, new and different organisms started to form,
such as many bigger animals and mineralized plankton. These organisms directly influenced the
oceanic environments, which ends up affecting the newly developed biosphere.
Being intrigued by the topic, I decided to do some research about increasing oxygen
