Gabrielle's Geologic Timeline

Cambrian Period 541 MYA

541 BCE

The first period of the Paleozoic Era and of the Phanerozoic Eon. It is the earliest point of life's history on Earth. It witnessed the largest boom of evolution to date. The environment had become far more hospitable, due to photosynthesizing bacteria in stromatolites, churning out tons of oxygen. The climate was slowly warming and sea levels were rising. The mascot of this era is the trilobite, an extinct arthropod of which there have been many fossils found.

Ordovician Period 488 MYA

488 BCE

In this period, the supercontinent of Gondwana began to slip down toward the South Pole, drowning the majority of itself underwater. The weather was extremely mild and moist, but cooled drastically when Gondwana finally reached the South Pole. Life stayed underwater. Major species of this time include trilobites, algae, and brachiopods. Many species of graptolites and conodonts went extinct during this time, perhaps due to the cooling temperatures in the later part of the period.

Silurian Period 443 MYA

443 BCE

In this period, landmasses were slowly drifting near each other, ready to collide in the following period. Gondwana, Baltica, and Laurentia are the landmasses in question. Sea levels were also rising, and shallower seas becan to be created, exposing more life to sunlight, spawning the first reef ecosystems. The Agnatha, a form of jawless fish, and early forms of coral were common. 85% of life species went extinct in the early portion of the era, perhaps due to cooling temperatures.

Devonian Period 416 MYA

416 BCE

Also known as "The Age of Fishes", the Devonian Period is when the supercontinents Euramerica and Gondwana collided to form the infamous Pangaea. Placoderms, or armored fish, became dominant predators, and cartilaginous fish like sharks were common by the late Devonian period. The ancestors of modern fish also became common. The first organism to walk on land was Tiktaalik. The Kellwater and Hangeburg Events sapped marine life of 70% of life, but plants and landwellers remained unaffected.

Carboniferous Period 356 MYA

356 BCE

This period is famous for the formation of swamp forests. Large deposits of organic material created the large coal deposits still ciphoned by humans to this day. Organisms present during this period include giant centipedes and smaller amphibian ancestors. Pangaea was still being formed by this point. The seas were not as vibrant with life due to the past two event wiping out 70% of life in the seas.

Permian Period 299 MYA

299 BCE

Pangaea had multiple different climates upon it during this time due to its large size. Early reptiles began to slowly dominate the planet while staying in warmer climates. Scientists believe that the worst extinction event in history, the Permian extinction, occurred due to extreme volcanic activity that wiped out 90% of all marine life and 70% of all terrestrial life.

Triassic Period 251 MYA

251 BCE

This was the first part of the three parts of the Mesozoic Era, of "The Age of Reptiles". The land climate was mostly dry. The weather had hot summers and chilly winters. Reptiles began to slowly dominate the land. Pangaea would eventually split into Laurasia and Gondwana. Life in the oceans would be somewhat barren for a time, but was slowly coming back from the Permian event.

Jurassic Period 199 MYA

199 BCE

Pangaea had finally split up, with Laurasia moving north and Gondwana remaining near the south. Sea levels rose and the climate became extremely humid, perfect weather for giant reptiles. The oceans were once again full of life, especially in the newly formed shallow seas. The dinosaurs, like the Allosaurus, and the earliest bird, Archaeopteryx, were common. Early mammals were also running around during this period.

Cretaceous Period 145 MYA

145 BCE

This marks the end of the Mesozoic Era and the Age of Dinosaurs. The continents looked very much like they do in present times today. Some animals popular during this time include the Tyrannosaurus rex and the Iguanodon. The K-Pg event marks when a giant asteroid struck Earth and wiped out most of the dinosaurs. The climate was still warm and humid.

Tertiary Period 65 MYA

65 BCE

This is the Age of Mammals. Dinosaurs were extinct, so animals were beginning to take on more mammalian biologies.The continents did not really move from how they had in the last period. The climate changed drastically. A mini Ice Age occured. The seas were largely unaffected.

The Quaternary Period 1.8 MYA

1 BCE

Man began to emerge. The climate had warmed considerably enough to allow for early hominids to evolve into the first humans. The continents and seas again were largely unchanged by this, and life evolved to fit with changing conditions. The Ice Age from the previous period may have killed off a large number of early mammals, but enough survived to become what we know today as modern animals.