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Evolving Planet- Biology Extra Credit
Transcript of Evolving Planet- Biology Extra Credit
The early Earth's environment was quite different from how it is today. Exploding volcanoes spewed lava and gases everywhere while the first land and seas formed. How did life begin though? Scientists have two theories as to how life first started: 1) Organic compounds may have formed on Earth in vents deep on the ocean floor
2) Organic compounds may have been carried to Earth from outer space in meteorites
The Cambrian Period was a world of water. Most of the animals lived in the shallow oceans. There, the animals developed skeletons and the first vertebrates appeared. Many of the creatures from this time period look similar to the ones we see today.
Life was changing more in the Silurian Period. Earth's empty lands became green with the plants that populated it. The oceans were now filled with huge reefs, containing interesting creatures. Some sea creatures started to colonize the plant filled land including the first tetrapods, or four-limbed vertebrates.
~ 290 million years ago
~ 65 million years ago and 1.8 million years ago
- A LOOK INTO EARTH'S HISTORY
First there was nothing...
...but over time, earth evolved
Let's go back to the beginning and see how it all started...
4.5 billion years ago life began on Earth...
The ozone layer formed, leading the way for the creation of the first organisms. Simple prokaryotes , and then eukaryotes, were the first forms of life. Photosynthesis and sexual reproduction helped organisms evolve in to what they are now.
~ 4.5 billion years ago
~ 543 million years ago
~ 443 million years ago
~ 354 million years ago
This period was filled with swampy forests that spanned across the clustered continents. These forests were filled with a whole range of different plants, insects, and spiders. The plants that lived in these forests became the coal that we use today!
By this period, the continents have moved together to form one huge super-continent: Pangaea. Three basic environments (dry, tropical, and mild,) sustained a vast variety of animals and plants. Two new animal groups appeared: reptiles and synapsids, and they spread across the land.
~ 248 million years ago
THE AGE OF THE DINOSAURS
This era is made up of the Triassic, Jurassic, and Cretaceous periods, which were filled with the largest animals ever known to walk this planet: dinosaurs. As well as dinosaurs, reptiles and flowering plants also made their first appearance.
While the Mesozoic Era was filled with dinosaurs, the Tertiary Period was the Age of Mammals. Many of the mammals in this period, such as hoofed mammals, rodents and carnivores, are very similar to the ones we see today.
The Quaternary Period was the Ice Age, which brought upon a mass extinction. New land bridges also formed where a great migration of animals occurred. Animals in this period were huge, like the mammoth for example.
~ appear 8 million years ago
humans originated from primates
our nearest primate relatives are apes
humans also belong to the hominid family that is made up of many species such as the Australopithecus species and the Neanderthals
Hominids have a few key factors in their past: one of their main distinctions between primates is that they walked on land (they were bipedal), they had bigger brains related to their body size which meant that they were more sophisticated than other mammals, and they had remnants of body parts that belonged to primates that we no longer use
Now that we've seen what the past looks like, let's see the present!
there were 6 mass extinctions
FIRST MASS EXTINCTION
occurred 465 million years ago
An ice age might have caused it. Many species couldn't survive the cooler temperatures. At least 70% of the species went extinct.
SECOND MASS EXTINCTION
occurred 370 million years ago
Continental drift might have caused this mass extinction. The movement of Earth's continents might have triggered environmental changes. Up to 70% of all marine species died.
THIRD MASS EXTINCTION
occurred 251 million years ago
This was the most devastating mass extinction of all. Scientists aren't exactly sure, but global warming caused from the intense heat of many volcanic eruptions might have been the reason. 9 out of 10 species died.
FOURTH MASS EXTINCTION
occurred 225 million years ago
Shifting continents triggered conditions that may have led to extinction. At sea, sea levels dropped, eliminating a habitat for marine animals. On land, volcanic activity led to global warming.
FIFTH MASS EXTINCTION
occurred 65 million years ago
Scientists think that a giant meteor crashed into the earth and the energy it created caused a chain reaction. The tremendous heat from the impact raised global temperatures and the impact also could have caused tsunamis which destroyed habitats.
SIXTH MASS EXTINCTION
started around 10,000 years ago and is still happening today.
Early on, extreme climate and environmental change may have led to species loss but today human activity is destroying habitats.