Jamie Miller Jordan Lewis Block 7

The Tertiary era began 65 million years ago, and last more than 63 million years (only 1.8 million years ago). This period marked the beginning of the Cenozoic era. The Tertiary era consists of 5 epochs:  The Paleocene Epoch – 65 to 54 million years ago  The Eocene Epoch – 54 to 38 million years ago  The Oligocene Epoch – 38 to 24 million years ago  The Miocene Epoch – 24 to 5 million years ago  The Pliocene Epoch – 5 to 1.8 million years ago  Each of these epochs were very unique in their changes of climate, animals, plants, and geography.

 The Paleocene epoch began with quite a bang, literally. The K-T Event was a large extinction, believed by scientists to be initiated by a large asteroid impacting in the Yucatan Peninsula area of Mexico. A global darkening was beginning to occur. The impact of the asteroid caused mass damage resulting in firestorms, which created dust, soot, and debris occluding the atmosphere to sunlight. The global darkening was enough to completely halt photosynthesis, resulting in widespread starvation and the extinction of the dinosaurs.  Thus began the rise of the mammals as the dominant land species. With the climate settling down and becoming less harsh, there was no pressure of extreme evolutionary changes. With no dinosaurs or drastic evolutionary changes. There was now a lack of predators, allowing these land mammals to thrive – thus building a bridge toward the evolution of homo sapiens. The Paleocene epoch also was the beginning of pine trees, and avian species. Condylarths, the ancestors of modern hoofed herbivores, became abundant.

 For most of the Eocene epoch, the global climate was quite warm and rainy. Mammals were now the dominant species of earth, and also were able to find ways to travel from continent to continent thanks to the newly formed land bridges. Ice caps were quite small, and sea levels were also quite low, thus creating land bridges through the Bering strait connecting north America and Asia. Land bridges were also formed connecting north America and Europe via Greenland, as well as the last land bridge connecting Australia and Antarctica.  The Eocene epoch also dawned the beginning of modernized mammals such as hoofed animals, rhinoceroses, bats, rabbits, beavers, rats, mice, whales, and carnivorous animals. Eohippus, the first horse, also became present. However, aquatic and insect life were much as they are today. Much of the vegetation also was evolving, including the new abundance of grasses. Familiar trees such as birch, cedar, chestnut, and elm were also now flourishing.

 The Oligocene epoch had a generalized cooling trend, as the Antarctic was freezing. The lack of moisture caused the land masses to be exposed to dry air. Tropical forests receded, while grass became very abundant. Grasslands led to the development of the digestive system in warm-blooded mammals (still the dominant land species). Herbivores became very common and many species, such as oreodonts( a sheep-like species) and artiodactyls, flourished. Cats and dogs also adapted to prey on the many herbivores. This climatic change created stepping stones to further diversify and develop animals through evolution.  India collided with Asia, which increased volcanic activity. Gondwanaland, (a supercontinent made up of South America, Africa, Madagascar, Antarctica, India, other parts of South Asia, and Australia), completely broke apart as Australia and South America separated from Antarctica. As the continents drifted into their respectful positions, the collisions also created mountains.

 The Miocene epoch brought forth a big advancement in historical findings with the first known fossils of primate and human evolution, the Ardipithecus Ramidus, dating back to approximately 6 million years ago. In addition, the fossils of the first primate carry supportive evidence that they could walk upright.  During the Miocene epoch stage, the Eurasian plate and Arabian plate became fused, thus creating a land bridge connecting Africa and Asia. This would allow migration of different species, and the mixing of genetic traits. Other notable findings state that the grassland areas were becoming much more developed and urbanized by animals. Due to the climate becoming cyclically warmer and back to being cold, kelp forests also became well developed because of less humidity.

 The Pliocene Epoch was the final and shortest of the epochs. By the end, the earth’s continents would assume their current positions in present day. The Indian plate was running into the Eurasian plate, causing both to uplift, resulting in rapid mountain building. The collision was ongoing though, causing ancient oceanic crust containing marine fossils to be uplifted into the Himalayan chain. There was also now a land bridge connecting North and South America at the isthmus of Panama allowing the further migration of species.  In this time there was a very noticeable increase in the evolutionary documentation of man and primates. In Africa, the retreating forests caused apes to come down from their trees and live life out in the open where they would co-exist with other animals such as elephants, antelope and other animals. Their now erect posture was necessary in the lookout for predators. This also gave them the freedom of their hands for makeshift tools such as sticks.

Brontotherium  Brontotherium was a very large, distant ancestor of the rhinoceros that lived during the late Eocene and early Oligocene Epochs. The term “Brontothere” was born from the Sioux Indian mythology, who believed these beasts would produce thunderstorms by running across the clouds.  Weighed in at nearly 5 tonnes. Also, was about 16 feet long, and 8 feet tall.  The large horn on their head was made out a thin bone, therefore would shatter easily if used in combat. It was rather used for display purposed only during mating. Males with a larger crest would have a higher chance of attracting a female.  Although you may think otherwise based on its size, Brontotherium was actually a herbivore. They actually had no teeth, but instead had molars which would help for chewing and digestion.

 During the Tertiary period, mammals ruled the world! Hominids appeared and continually evolved. Many birds of our time were also present, with the larger flightless birds becoming extinct. Insects, especially pollinating insects, such as bees, populated the earth more so than before due to widespread pollinating plants. Fish species diversified, such as trout and bass, and sharks grew in numbers.  Geologically, the world cooled. Glaciations occurred at both poles. Many new mountain ranges formed, such as the Himalayans and the Alps. Land bridges appeared at this time, connecting Asia to North America, Great Britain to Europe,and South East Asia to Borneo. This was caused by the glaciers as they retained mass amounts of water, which lowered the sea level drastically.

Brontotherium Paleocene Epoch Eocene Epoch Oligocene Epoch Miocene Epoch Pliocene Epoch