The Triassic Period is characterized by two main geologic events. The first was the creation and subsequent rifting of the supercontinent Pangaea. The second was the evolution of dinosaurs and mammals.Know More
At the beginning of the Triassic Period, the continents came together to form one large supercontinent called Pangaea. Pangaea was C-shaped and located on the equator. During this time, there were no ice caps at the north or south poles, causing a hot, dry climate. By the end of the Triassic Period, Pangaea began to rift and separate into two landmasses: Gondwana and Laurasia.
By the middle to late Triassic Period, dinosaurs and mammals evolved. Large reptiles called Therapsids were dominant during this period, and they were eventually replaced by Archosaurs. Archosaurs evolved to become bipedal, marking the beginning of dinosaurs. Aquatic reptiles and small, bird-like reptiles were also present.
The first observation of mammals occurred in the late Triassic Period. The Eozostrodon, a shrew-like mammal, was approximately 3 feet long. There is still much that is unknown about early mammals, but it is evident they had fur and three ear bones, and produced milk to feed their young. The Triassic Period ends with the Triassic-Jurassic mass extinction that widely affected ocean life and ushered in the dinosaur-dominated Jurassic era.Learn more about Geology
In the long geological history of the Earth, humans first appeared during the Pleistocene Epoch, which dates back 1.6 million years to 10,000 years ago. Humans in modern form arrived during the Pleistocene Epoch, although human-like creatures appeared in the period just before the Pleistocene, called the Pilocene Epoch, which dates back 5 million years ago to 1.6 million years ago.Full Answer >
The geologic era in which humans have evolved and spread over the Earth is the Cenozoic Era. This time period began roughly 65 million years before the start of the 21st century.Full Answer >
Major events during the Jurassic included the further breakup of the supercontinent Pangaea, the development of subtropical conditions and larger dinosaurs. The earliest bird also took flight during the late Jurassic, and early mammals emerged that would later dominate the Earth.Full Answer >
Sedimentary rocks are primarily characterized by lithification. Lithification occurs when sediment has been deposited and accumulates at the earth's surface or in bodies of water to form a rock over time. Subgroups of sedimentary rocks are defined by their specific formation.Full Answer >