NATS 1940- Final Exam Guide - Comprehensive Notes for the exam ( 116 pages long!)

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Animals, plants - coming in a different variety of colours. A measure of the number of different species in a defined area. Example: a measure of the number of ecosystem types (grassland, deciduous forest, desert, etc. ) on a continent. Fossil record shows that 99% of all species that ever lived are extinct. When a large portion of the earth"s species are wiped out in a short span of time. There have been 5 major mass extinctions during the time that animal life has existed on earth (about 600 million years ago) Impact site: north coast of yucatan peninsula (mexico) Fossils are a good way to learn about these extinctions, they are found in. Fossils are a good way to learn about these extinctions, they are found in sedimentary rocks that form under water and they"re formed in layers. Older layers at the bottom, and more recent fossils are at the top.