____ are the preserved remains of formerly living organisms. The ____ refers to the history of life on Earth as documented by the fossils known so far. Earliest fossils are organisms made up of a single simple ____. Life increased in ____ as organisms with complex cells and then multicellular appeared. ____ occurs when there is a sudden increase in the variety of species that change to their environment. ____ occurs when large numbers of species go extinct over a short period of time. There have been ____ mass extinctions in Earth's history. Living things ____ over time. Scanning and printing fossils allows scientists to study them without ____ them.

Grade 6 Science Fossils

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