Project Relife: 2x Isekai System

Chapter 99: Cenozoic Period

Tiny fragments likely stayed in the atmosphere, possibly blocking part of the sun's ray for months or years. With less sunlight, plants and the animals dependent on them would have died, Kruk said. Furthermore, the reduced sunlight would have lowered global temperatures, impairing large active animals with high-energy needs, she said.

"Smaller, omnivorous terrestrial animals, like mammals, lizards, turtles, or birds, may have been able to survive as scavengers feeding on the carcasses of dead dinosaurs, fungi, roots and decaying plant matter, while smaller animals with lower metabolisms were best able to wait the disaster out," Kruk said. 

There is also evidence that a series of huge volcanic eruptions at the Deccan traps, located along the tectonic border between India and Asia, began just before the K-Pg event boundary. It is likely that these regional catastrophes combined to precipitate a mass extinction.

The world was a warmer place during the Cretaceous period. The poles were cooler than the lower latitudes, but "overall things were warmer," Kruk told Live Science. Fossils of tropical plants and ferns support this idea, she said.

Animals lived all over, even in colder areas. For instance, Hadrosaurus fossils dating to the Late Cretaceous were uncovered in Alaska. 

When the asteroid hit, the world likely experienced so-called "nuclear winter," when particles blocked many of the sun's rays from hitting Earth.

After the nuclear winter it was the time of third major era of earth's history, the Cenozoic era.

The Cenozoic era, which began about 65 million years ago and continues into the present, is the third documented era in the history of Earth. The current locations of the continents and their modern-day inhabitants, including humans, can be traced to this period.

The era began on a big down note, catching the tail end of the Cretaceous-Paleogene extinction event at the close of the Cretaceous period that wiped out the remaining non-avian dinosaurs.

As per Xin's understanding, The Cenozoic era is divided into three periods: Paleogene period (65-23 million years ago), which consists of the Paleocene, Eocene and Oligocene epochs);

Neogene period (23-2.6 million years ago), which includes the Miocene and Pliocene epochs);

Quaternary period (2.6 million years ago to the present), consisting of the Pleistocene and Holocene epochs). While it is widely accepted that we are still in the Holocene epoch, some scientists argue that we have entered the Anthropocene epoch. In a 2010 article in the scientific journal Environmental Science & Technology, scientists made the case for a new epoch, blaming humans for causing a drastic shift in conditions.

Now coming to the climate the global climate of the early portion of the Cenozoic period was much warmer than it is today, and the overall climate of the Earth was much more consistent regardless of proximity to the equator.

The most significant period of global warming, known as the PaleoceneEocene Thermal Maximum, took place of 55.8 million years ago. It was followed by a long cool, dry period. The current global warming event has been set off primarily by human activity.

Each segment of the Cenozoic experienced different climates. During the Paleogene period, most of the Earth's climate was tropical. The Neogene period saw a drastic cooling, which continued into the Pleistocene epoch of the Quaternary period.

As for the changing landscape, the continents drifted apart during the Paleogene period, creating vast stretches of oceans. This had a significant impact on the climate and marine life surrounding each continent.

During the Pleistocene epoch, glaciers covered central North America, extending as far east as New York, south to Kansas and Nebraska and west to the northern West Coast. The Great Lakes were formed as the glaciers receded.

Several of the world's foremost mountain ranges, including the Alps, Himalayas and the Rocky Mountains, were formed during the Cenozoic era.

The Cenozoic era is also known as the Age of Mammals because the extinction of many groups of giant mammals, allowing smaller species to thrive and diversify because their predators no longer existed. Due to the large span of time covered by the period, it is beneficial to discuss the animal population by the milestone of the era rather than in generalities.

The beginning of the Paleogene period was a time for the mammals that survived from the Cretaceous period. Later in this period, rodents and small horses, such as Hyracotherium, are common and rhinoceroses and elephants appear. As the period ends, dogs, cats and pigs become commonplace. Other than a few birds that were classified as dinosaurs, most notable the Titanis, the dinosaurs were gone. Large flightless birds, such as the Diatryma, thrived. 

The Neogene period gives rise to early primates, including early humans. Bovids, including cattle, sheep, goats, antelope and gazelle, flourish during this period.

Cave lions, sabre-toothed cats, cave bears, giant deer, woolly rhinoceroses, and woolly mammoths were prevailing species of the Quaternary period.

Without the dinosaurs, plant life had an opportunity to flourish during the Cenozoic era. Nearly every plant living today had its roots in the Cenozoic era. During the early part of the era, forests overran most of North America. However, as the climate cooled forests died off, creating open land.

Due to the widening of the oceans, sharks, whales and other marine life proliferated. The Great Lakes that formed in the western United States during the Eocene epoch were the perfect home for bass, trout and other fresh-water species.

As the forests thinned, grasses began to spread out over the plains of North America and savannas covered the land in the middle of the continent. Among the common plant life were pines, mosses, oaks and grasses. Flowering plants and edible crops dominate the landscape in the later part of this era as humans cultivate the land.

After Cenozoic it was time for the Paleogene period.

The Paleogene Period was the first of three periods comprising the Cenozoic Era. The Cenozoic, sometimes known as the "Age of Mammals", as the Mesozoic was the "Age of Reptiles", is known by its Epochs. The Paleogene is composed of the first three of these Epochs, (Paleocene, Eocene, and Oligocene Epochs).

Four additional Epochs comprise the Neogene and Quaternary Periods that are to follow. The Paleogene sees the rapid filling of the environment following the K/T extinction, though it took more than two million years for the Earth's ecosystems to recover from this event.

On land primitive mammals and birds began to spread rapidly.  In the seas planktonic foraminifera and nanofossils begin new evolutionary paths. 

Most marine life resembles modern forms: the wonder of Cenozoic fossils is seeing recognizable organisms cast in stone, rather than the exotic, 'alien' life forms, such as sea lilies, ammonoids, and trilobites, of the Mesozoic and Paleozoic Eras. The three Epochs are discussed in more detail below. Additional information about the mammals of these epochs can be found in our Prehistoric Mammals of the Cenozoic exhibits.

Small mammals and birds diversify in dense forests as Earth recovers from the (K-T) extinction. The loss of the giant reptiles that dominated the Mesozoic Era left the world open for evolutionary experiments by mammals and birds as they filled Earth's environments in turn.

The diverse mammalian fauna remained small, the largest only the size of a small pony. Ferns were initially abundant following the K-T extinction, but flowering plants and conifers soon took over as they returned to abundance.

Deciduous trees dominated swamp forests in North America from middle latitudes to the Arctic ocean. Grasses, an immensely important group in later epoch ecologies, originated early in the Paleogene. Insect herbivory finally recovered from the K-T extinction event in the late Paleogene, nine million years after the event.

In the oceans, most reptiles vanished, turtles and crocodilians being exceptions. Sharks and teleost fish become more common, and bony fishes dominate the seas as they will continue to do to the present day. Among invertebrates more modern forms of gastropods and bivalves, foraminiferans and echinoids appear. 

As a result of various geological events like the island continent of India colliding with Asia, there was a rapid worldwide rise in temperature at the end of the epoch.

The Eocene begins with extreme Global warming, the warmest five million years of the Cenozoic. This warming was probably due to a large methane release from the ocean floor. As a result of global warming trees grew even in Polar Regions, while subtropical or tropical angiosperm forests cover most of what is now the United States. Palm trees grew in Alaska and Spitzbergen island and crocodilians lived above the Arctic circle.

Many new grasses evolve. However, grasslands had yet to develop and herbivorous mammals were browsers, feeding on leaves and herbs rather than grass. 

The first odd-toed mammals (perissodactyls, such as rhinos and horses) and even-toed mammals (artiodactyls such as camels) were present at the beginning of the epoch. 

The first marine mammals, including the first whales, appear in the seas, and the first primates appear on land. Large mammals make their first appearance on land, then die off by the end of the epoch. Carnivores include the first members of the dog, weasel, bear and cat families. Most modern orders of bird had appeared by the Eocene. 

Africa is now an island continent. The climate began the long cooling trend that would continue through the Cenozoic in the middle of the Eocene.