Paleontology--Mesozoic

found: Encyc. Britannica online, July 15, 2014(Phanerozoic Eon, the span of geologic time extending about 542 million years from the end of the Proterozoic Eon (which began about 2.5 billion years ago) to the present. The Phanerozoic, the eon of visible life, is divided into three major spans of time largely on the basis of characteristic assemblages of life-forms: the Paleozoic (542 million to 251 million years ago), Mesozoic (251 million to 65.5 million years ago), and Cenozoic (65.5 million years ago to the present) eras)

found: Palaeos website, July 15, 2014(The Phanerozoic Eon; The term Phanerozoic - "visible" or "revealed life", or "evident life" - is generally applied to the Paleozoic, Mesozoic and Cenozoic eras)