The White House is defending President Donald Trump's chief of staff after he mischaracterized previous remarks of a Democratic congresswoman who is now criticizing Trump's condolence call to the widow of a soldier killed in Niger.John Kelly on Thursday derided Rep....
Dinosaurs lived throughout the Mesozoic Era, which began 245 million years ago and lasted for 180 million years. It is sometimes called the Age of the Reptiles. The era is divided into three periods.45 to 208 million years ago. 1  During the Triassic period, all land on Earth existed as one enormous mass. 2  It was called Pangaea. 3  The supercontinent slowly began to break up during the Triassic Period.
Geologists generally agree that there are two major eons: the Precambrian eon and the Phanerozoic eon. The Precambrian goes from the formation of the earth to the time when multicellular organisms first appeared-that's a really long time-from 4,500 million years ago to just about 543 million years ago.