Shirtless Guy
Old Dirty Basterd
Re: Obama XV: Now, with 20% more rage
The first true mammals appeared in the Late Triassic (ca. 200 million years ago). 200 million years ago the 30 Myr filter shows concentrations of around 2000 ppmv. The royer compilation data shows periods of time where concentrations were at or above 2000 ppmv for most of the Triassic, Jurassic, and Cretaceous periods, its not until the Paleogene and Neogene periods that we see such low levels. That leads me to believe there is an extreme wide range for an acceptable level in the atmosphere. Mammals most certainly did exist during much of the period I mentioned and certain animals have existed over the entire period I mentioned (crocodiles).Wait, what?!?
Human life as we know it (crude operationalization: homo sapiens) has been around for how long? Pretty sure it's well under a million years, never mind 400-500 million.
Which begs the question: What sort of life, exactly, was thriving 400 million years ago? I'm no paleobiologist, but I'm pretty sure they weren't mammals.
Which begs the question: What's the relevance, again?