Carrier's constant

In order to better understand what to look for in fungal-mammalian co-evolutionary patterns, I've been looking to educate myself about how and where mammals evolved. During the course of that, I ran across this wiki article. Am I missing something, or does the following sentence abrogate any need for us to consider this constraint? "Contrary to the above model, breathing is maintained in lizards during movement, even above their aerobic scope, and arterial blood remains well oxygenated."