Geoscience Reference
In-Depth Information
and Emma were wrong. Instead, it is possible that while these other ani-
mals were large, they were more sedentary with lower oxygen demand
than a comparably sized fish. A more detailed look at the physiology of
large and small, fast and slow, swimmers in the sea will be important in
untangling these issues.
Indeed, we have plenty more to learn. The Phanerozoic Eon, how-
ever, with its rich fossil record and relative abundance of sedimentary
rocks, offers the possibility for a good understanding of the history of
atmospheric oxygen levels. This history can be probed by multiple lines
of evidence, and it seems to encompass a beautiful relationship between
the evolution of atmospheric oxygen concentrations and the evolution
of life on Earth.