BIOL 2P05 Lecture Notes - Lecture 1: Evolutionary Arms Race, Cambrian Explosion, Precambrian
11 Apr 2017
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Document Summary
Ctenophores, sponges, and cone jellies don"t have neurons but they are able to process information. Unknown tree of life is constantly changing: placoderms have no neurons but they have na+ and k+ channels. Evolved things necessary to process information: immune systems. Sponges are able to recognize themselves in order to aggregate properly. About 750 to 580 mya, a series of ice ages gripped much of the earth. Glacial deposits from this time have been found all over the world, and may have extended to the equator. Some scientists envision a snowball earth : glaciers covered earth"s continents and its oceans were frozen at the surface. Rapid warming and deposition of carbonate rocks followed such extreme periods of cold, perhaps. Range in age from 600 to 545 mya. 2 exceptions: all metazoans from this time lacked mineralized skeletons. Majority of species disappear with the exception of sponges.
