More Bacteria Blogging
This CNN article may point to the reason a simple life form can live, for a given value of live, so long:New organism raises Mars questions
It is about the discovery of bacteria in an Alaskan core sample that when brought to room temperature came back to life. The section of the sample being studied was 30,000 years old and consisted of permafrost.
If this bacteria can withstand being frozen for millennia, It is possible that the 16 million year old bacteria in the previous sample was only actually "alive" for a very short period of those years, going dormant when life wasn't sustainable.
Some reptiles go dormant for extended periods in underground cells during drought, there's a frog in Canada that is frozen during the winter, and we just went through the miracle/annoyance of the cicadas.
Given what we know about the extended dormant life of spores, this is a reasonable hypothesis, but study needs to be done.[Edit: It would be nice to take a few years off and come back in September, 2008.]