What Happened to the Trilobites?? The Ordovician period was a time of great change. The Cambrian explosion had resulted in almost every major phylum of organisms evolving in a period of 40 million years (Freeman & Herron, 1998). It was also a time of the great radiation. This allowed existing life forms to develop adaptations and variations, which led to new species (Droser et al. 1996). This also allowed a huge diversity of species, especially in comparison to today. …showed first 75 words of 862 total…

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