Events in Earth's History

Events in Earth's History

MUSE, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons

The formation of the Moon

first bacteria

First Vertebrates

Christinelmiller, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons

Daniel J. Geduld (2011) CIL:39018, Cucumis sativus, plant cell, cucumber peel. CIL. Dataset. https://doi.org/doi:10.7295/W9CIL39018

First land Plants

Oxygen

First Cells

CSIRO, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons

Apokryltaros, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons

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Events in Earth's History

First Dinosaur

Chicxulub crater

Pangea

Theodolite, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons

H. Raab (User: Vesta), CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons

First Humans

First Mammals

Kentaro Ohno, CC BY 2.0 <https://creativecommons.org/licenses/by/2.0>, via Wikimedia Commons

Jack Jackie Pomi, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons

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Earth's Mass Extinctions

440 Million Years Ago

The Future

You are Here

66 Million Years Ago

200 Million Years Ago

251 Million Years Ago

375 Million Years Ago

(Mesozoic Era)

(Mesozoic Era)

(Cenozoic Era)

(Paleozoic Era)

(Paleozoic Era)

(Paleozoic Era)

Timeline Interactive

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Geologic Time Scale ERAs

Paleozoic Era 541 Million- 252 Million Years Ago

Mesozoic Era 252 Million- 66 Million Years ago

Precambrian 4.6 Billion- 541 Million Years ago

Cenozoic Era 66 Million- Present Day

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LATE DEVONIAN EXTINCTION

• This extinction event occurred ~375 million years ago.
• As land plants began to grow rapidly, they consumed atmospheric carbon dioxide which caused global cooling. (Remember, CO2 is a greenhouse gas that traps heat).
• As plant roots weathered the soil, it released nutrients into the sea, which in turn caused algae blooms and oxygen depletion.
• 75% of species went extinct (marine life).

Late-Devonian seafloor recreation

James St. John, CC BY 2.0 <https://creativecommons.org/licenses/by/2.0>, via Wikimedia Commons

Chicxulub crater

The Chicxulub crater is like a giant scar on Earth's surface, buried deep under the Yucatan Peninsula in Mexico. It's one of the biggest craters on Earth, wider than some states! Scientists believe this crater was formed by a super powerful crash between Earth and a giant space rock called a meteor, way back in time (about 66 million years ago). Imagine the biggest fireball you've ever seen, but a million times bigger! This crash is thought to have caused some serious trouble for Earth. It likely triggered giant tsunamis, wildfires, and dust clouds that blocked out the sun for years. These changes were so dramatic that many dinosaurs, and many other living things, could not survive.

Mesozoic Era

The Mesozoic Era lasted from about 252 million years ago to 66 million years ago, spanning roughly 186 million years. Key Features:

• Known as the “Age of Reptiles”

• Dinosaurs were the dominant land animals

• First birds appeared

• First flowering plants (angiosperms) evolved

H. Raab (User: Vesta), CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons

First Vertebrates

The first vertebrates evolved in the ocean 515 million years ago. It is hypothesized that the first vertebrates were jawless fish.

James St. John, CC BY 2.0 <https://creativecommons.org/licenses/by/2.0>, via Wikimedia Commons

This fossil jawless fish from the Lower Devonian Beartooth Butte Formation, from an outcrop in the western flank of the Bighorn Mountains, northern Wyoming, USA.

END of the ORDOVICIAN EXTINCTION

Late-Ordovician seafloor recreation

• This extinction event occurred ~444 million years ago.
• Drastic changes in temperature caused glacial and interglacial events, which in turn caused sea levels to rise and fall dramatically.
• Changing sea levels caused shoreline erosion, which impacted ocean chemistry.
• 80% of species went extinct (marine life).

James St. John, CC BY 2.0 <https://creativecommons.org/licenses/by/2.0>, via Wikimedia Commons

Triassic Extinction Event

Triassic Landscape

• This extinction event occurred ~200 million years ago.
• Underwater volcanic activity caused a mass extinction event similar to the Permian extinction- CO2 in the atmosphere caused global warming and ocean acidification.
• 80% of species went extinct (amphibians, reptiles, conodonts, corals, ammonites, and brachiopods).

Paleozoic Era

Paleozoic Era lasted from about 541 million years ago to 252 million years ago, spanning roughly 289 million years. Known for the rise of complex life and movement of life from water to land. Key Features:

• First vertebrates, land plants, and insects appeared

• Reptiles and amphibians began to diversify

• Ended with the largest mass extinction in Earth’s history

First Humans

The ancestors of modern day humans (Homo sapiens) evolved 200,000 years ago. Based on the fossil record and DNA evidence, we have concluded that the first humans originated in Africa. The map above shows the the spreading of Homo sapiens over the past 200,000 years.

The Moon

The Impact: Scientists believe a giant object, possibly the size of Mars, called Theia (after the Greek Titan), slammed into the early Earth. This colossal collision sent a huge amount of debris flying into space. Birth of the Moon: The leftover debris from the impact is thought to have come together, due to gravity. Over time, this material formed the Moon in orbit around Earth. Molten Beginnings: The immense energy from the impact likely caused both the early Earth and the Moon to be in a molten state.

Gradual Solidification: Over millions of years, the Moon and Earth gradually cooled and solidified, forming the celestial bodies we know today. This is the most widely accepted theory, but there are other ideas that scientists continue to explore.

Cenozoic Era

The Cenozoic Era began 66 million years ago and continues to the present day. Key Features:

• Known as the “Age of Mammals”

• Mammals and birds diversified and became dominant

• Modern plants and ecosystems developed

Larry D. Moore, CC BY 4.0 <https://creativecommons.org/licenses/by/4.0>, via Wikimedia Commons

Cretaceous Extinction Event

Cretaceous Landscape

• This extinction event occurred ~66 million years ago.
• The main factor that triggered this extinction event was an asteroid impact that hit in modern day Mexico. The asteroid caused super-heating followed by rapid cooling.
• Prior to the impact, volcanic activity was affecting atmospheric temperatures and ocean chemistry. Animal species were already stressed and the impact pushed them over the edge.
• 75% of species went extinct (dinosaurs, mosasaurs, mammals, ammonites, plants).

ANTHROPOCENE EXTINCTION?

The word anthropogenic means caused by human activity. Things humans are doing today (burning fossil fuels, clear cutting forests, over farming) are increasing carbon dioxide levels, accelerating global warming, and causing ocean acidification just like we saw in prior mass extinctions. Humans are also causing habitat loss, overfishing, contributing to invasive species, and reducing biodiversity.

The Permian Extinction

Permian forest floor recreation

• This extinction event occurred ~251 million years ago.
• During this period there was a lot of volcanic activity.
• Volcanic gases (sulfur dioxide and carbon dioxide) entered the atmosphere and caused acid rain, ocean acidification, and global warming.
• 96% of species went extinct (amphibians, early reptiles, insects, and marine life)

James St. John, CC BY 2.0 <https://creativecommons.org/licenses/by/2.0>, via Wikimedia Commons

Early Oxygen

As cyanobacteria completed photosynthesis, Banded Iron Formations formed between 3.8 and 1.8 billion years ago. A period when the Earth's atmosphere was undergoing a critical change. These formations provide valuable evidence about the conditions on early Earth. The presence of iron oxide minerals (red layers) suggests an abundance of iron in the oceans, while their formation requires free oxygen. This indicates that Earth's atmosphere was starting to transition from an anoxic state (lacking oxygen) to an oxygenic one (containing oxygen).

Graeme Churchard from Bristol, UK, CC BY 2.0 <https://creativecommons.org/licenses/by/2.0>, via Wikimedia Commons

Pangea

Continents are always on the move due to convection in Earth's mantle. Pangaea, a supercontinent, formed 260 million years ago.

Kious, Jacquelyne; Tilling, Robert I.; Kiger, Martha, Russel, Jane, Public domain, via Wikimedia Commons

Precambrian Time

The Precambrian is not a single era but rather the vast span of time before the Paleozoic Era it covers about 88% of Earth’s history. Length: Roughly 4.6 billion to 541 million years ago That means it lasted about 4 billion years. Key Events:

• Cooling of the crust and formation of oceans

• First simple life forms (bacteria, algae)

• Rise of oxygen in the atmosphere (Great Oxidation Event)