November 2007
One of the main theories that explains the existence of large arthropods in previous epochs is the fact that oxygen levels were sometimes much higher, allowing organisms which depend on passive diffusion, like insects, to grow larger. (This was a key aspect of a plot in last year’s TV hit Primeval which featured an unfeasibly large giant centipede from the deep past.) This is a difficult hypothesis to test, but these authors of an open access article in PNAS have done their best, looking at the evolution of trachaea in beetles.
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