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The term Tertiary dates to the 19th Century and relates to the fact that it was the third of four geologic periods identified by European geologists. It covers the time span between the demise of the Dinosaurs and a time in the recent past when periodic glaciations started and when recognizable human ancestors had evolved. |
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It covers roughly the time span between the demise of the dinosaurs and beginnning of the most recent ice age. During the Tertiary the modern families of birds, mammals and [flowering plant]?s evolved . [Marine invertebrate]?s and [marine vertebrate]?s other than the [marine mammals]? experienced only modest evolution. |
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The sixty million years of the Tertiary represents the time during which most modern families of birds, mammals and flowering plants evolved . Marine invertebrates and marine vertebrates other than the marine mammals experienced only modest evolution. |
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Continental drift was modest. India broke loose from Africa and attached itself to Asia. South America attached itself to North America toward the end of the Tertiary. Antarctica -- which was already separate -- drifted to its current position over the South Pole. Climates during the Tertiary slowly cooled starting off tropical to moderate worldwide in the Paleocene and ending up with extensive glaciations at the end of the period. |
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Continental drift was modest. India broke loose from Africa and attached itself to Asia. South America attached itself to North America toward the end of the Tertiary. Antarctica -- which was already separate -- drifted to its current position over the South Pole. Climates during the Tertiary slowly cooled starting off tropical to moderate worldwide in the Paleocene and ending up with extensive glaciations at the end of the period. |
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The term Tertiary was first used by Giovanni Arduino, possibly in a letter dated 1759 (dates on the web vary). He classified geologic time into primitive (or primary), secondary and tertiary periods based on observations of northern Italy (some pages on the web add a forth type, variously quaternary, volcanic or alluvial). In 1828 Charles Lyell incorporated a Tertiary period into his own far more detailed system of classification. He subdivided the Tertiary period into four epochs according to the percentage of fossil mollusk?s that resembled modern species, using greek names: Eocene, Miocene, Older Pliocene and Newer Pliocene. Later the use of mollusks was abandoned from the definition and the epochs were renamed and redefined. |
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