BIO 200 Chapter Notes - Chapter 25.1: Paleomagnetism, Igneous Rock, Continental Drift
2 Sep 2016
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The history of life on earth - chapter 25. 1. Dragonflies today have a wingspan about the size of our hand. 350-250 mya during the carboniferous and permian geological periods, the ancient dragonfly mageneuropsis permiana had a wingspan of over 70 cm (over 2 feet) Can"t survive today because of the considerably less concentration of oxygen in the atmosphere in comparison to that during the carboniferous and permian periods. High oxygen concentration in the atmosphere is thought to have been the cause of having such large creatures roaming the earth during ancient times. We know the age of fossils because of the layer of sediment they"re found in. The closer to the surface the fossil is, the more recent it existed. We now also know via radioactive decay a more exact age of the fossils (more precise than just finding out which layer the fossils were found in)
