Cenozoic. Mammals are the dominant terrestrial vertebrates of the Cenozoic.
The era began 65 million years ago. The Cenozoic is also known as the Age of Mammals, because the extinction of many groups allowed mammals to greatly diversify. Early in the Cenozoic, following the K-Pg event, the planet was dominated by relatively small fauna, including small mammals, birds, reptiles, and amphibians. From a geological perspective, it did not take long for mammals and birds to greatly diversify in the absence of the large reptiles that had dominated during the Mesozoic. Some birds grew larger than the average human. Climate-wise, the Earth had begun a drying and cooling trend, culminating in the glaciations of the Pleistocene Epoch, and partially offset by the Paleocene-Eocene Thermal Maximum. Subdivisions[edit] The Cenozoic is divided into three periods: The Paleogene, Neogene, and Quaternary; and seven epochs: The Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene, and Holocene. Tectonics[edit]
Neogene period. Quaternary period. Paleocene–Eocene Thermal Maximum. Climate change during the last 65 million years as expressed by the oxygen isotope composition of benthic foraminifera. The Paleocene-Eocene Thermal Maximum (PETM) is characterized by a brief but prominent negative excursion, attributed to rapid warming. Note that the excursion is understated in this graph due to the smoothing of data. The PETM is characterized by extreme changes on Earth’s surface,[5] whereby global temperatures rose by about 6 °C (11 °F). This warming extended from the tropics to high latitudes and the deep ocean. The PETM is also marked by a prominent negative excursion in carbon stable isotope (δ13C) records from across the globe; more specifically, there was a large decrease in 13C/12C ratio of marine and terrestrial carbonates and of organic carbon deposited on ocean basins.[5][6][7] This carbon isotope excursion (CIE) coincided with a marked shoaling of the ocean's carbonate compensation depth.
Key events in the Paleogene Setting[edit] Effects[edit] Sea level[edit] Cretaceous–Paleogene extinction event. Artist's rendering of a bolide impact A Wyoming (U.S.) rock with an intermediate claystone layer that contains 1000 times more iridium than the upper and lower layers.
Picture taken at the San Diego Natural History Museum Complex Cretaceous–Paleogene clay layer (gray) in the Geulhemmergroeve tunnels near Geulhem, The Netherlands. Finger is on the actual Cretaceous-Paleogene boundary. The Cretaceous–Paleogene (K–Pg) extinction event,[a] formerly known as the Cretaceous–Tertiary (K–T) extinction,[b] was a mass extinction of some three-quarters of plant and animal species on Earth—including all non-avian dinosaurs—that occurred over a geologically short period of time 66 million years ago.[2][3] It marked the end of the Cretaceous period and with it, the entire Mesozoic Era, opening the Cenozoic Era which continues today. A wide range of species perished in the K–Pg extinction. Extinction patterns[edit] Millions of years ago K–Pg The K–Pg extinction was a global event. Microbiota[edit]