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   Summary:

   The Triassic period. Era of Early Survivors

   150,000,000 years ago. At the beginning of this era, the eastern and central parts of North America, the northern half of South America, much of Europe and Asia were at a considerable height above sea level. For the first time, North America found itself in geographic isolation, but only for a short time, as the reappearing land bridge of the Bering Strait connected that continent to Asia.

   140,000,000 years ago, fully formed reptiles suddenly appeared, preceded only by two doreptiloid species that had inhabited Africa during previous epochs. They evolved rapidly and soon gave rise to the crocodiles and the scaly-armored reptiles, and later both the sea serpents and the flying reptiles.

   130,000,000 years ago the seas hardly changed. Siberia and North America were connected by a land bridge across the Bering Strait.

   120,000,000 years ago, a new period in the development of reptiles began. This stage was marked by the evolution and decline of the dinosaurs.

   100,000,000 years ago the age of reptiles ended. For all their enormous mass, dinosaurs were practically mindless animals, lacking the intelligence to provide their huge bodies with the necessary sustenance; that's why these lazy land reptiles were dying out in ever increasing numbers.

 

   This period, including the apogee and the beginning of the decline of the reptiles, lasted almost 25,000,000 years and is known as the Jurassic.

 

   Cretaceous period. Period of flowering plants and birds

   100,000,000 years ago, the North American continent and part of Europe were high above sea level. The distortion of the American continents continued, resulting in the transformation of the North American Andes, and the western plains of North America gradually began to rise.

   95,000,000 years ago, the American and European continents began to sink again. The Southern Seas cut into North America and gradually expanded northward, joining the Arctic Ocean; it was the second largest submersion on this continent.

   85,000,000 years ago the Bering Strait closed and isolated the cooling waters of the northern seas. Until then, the marine life of the Atlantic and Gulf of Mexico was significantly different from the marine life of the Pacific Ocean, which was explained by the difference in the temperatures of these two bodies of water; now the temperature has become the same.

   80,000,000 years ago, the Earth's crust underwent powerful perturbations. The westward drift of the continents ceased, and the colossal energy of the inertial motion of the rear continental mass smoothed the Pacific coasts of North and South America, initiating reciprocal changes along the Pacific coasts of Asia.

   75,000,000 years ago continental drift ended. Formation of the Pacific Coast Ranges from Alaska to Cape Horn is complete.

   70,000,000 years ago crustal deformation occurred associated with maximum uplift in the Rocky Mountain region. In British Columbia, a large segment of mountain ranges from a depth of more than twenty-four kilometers was thrown to the surface.

   65,000,000 years ago, it became one of the most extensive outpourings of lava flows in all of world history.

 

   Thus ends the long era in the history of world evolution that began with the emergence of early terrestrial life and ended with the later appearance of man's immediate ancestors and related offshoots. This period, the Cretaceous, covers more than 50,000,000 years and ends the era of evolution of terrestrial life until the appearance of mammals, which lasted 100,000,000 years and is known as the Mesozoic.