chapter 21 - Chapter 21 History Biogeography and...

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Chapter 21- History, Biogeography, and Biodiverstiy Millions of years of geologic time o Phylogenetic effects- characteristics shared by a lineage irrespective of environmental factors Affects diversification of specie o Not many fossils before 540 million years ago because animals lacked the skeletons or shells to form fossils o Divisions in geologic time coincide with changes in the flora and fauna of the earth that are perceived through the fossil record o Paleozoic era- means “old animals” From earliest appearance of animals with hard skeletons to a mass extinction event, 251 million years ago Most animals from this era are not extinct o Mesozoic era- means “middle animals” Also known as the age of reptiles 251 Mya to 65 Mya ended by mass extinction of animal taxa, including dinosaurs beginning of the time of early evolution of many prominent current groups, flowering plants, mammals, insects o Cenozoic era- meaning “recent animals” Also known as the age of mammals Present day Most present biodiversity is the product of the recent past Influenced by Continental Drift o Continents are islands of low-density rock floating on the denser material of the earth’s interior o Convection currents in the semi-molten material of the underlying mantel carry continents along o
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