Cretaceous
Storyboard Text
- During the Cretaceous period, the tropics were drier than current temperatures. Therefore, tropical rainforests did not exist. No tropical rainforests mean that the number of Cretaceous plants was scarce and did not grow as wealthy as they are today to absorb the carbon dioxide. In addition, The asteroid’s impact on Earth caused the extinction of animals, ejected a great deal of rocky debris into the atmosphere, and shrouded the planet in darkness for months or longer. With no sunlight able to penetrate this global dust cloud, photosynthesis ceased, causing green plants to die and the food chain to be disrupted.
- How about the planets and animals?
- Also, the some geological events led to ocean change. The splitting of the Cretaceous Pangaea supercontinent led to the formation of new oceans and changes in ocean circulation patterns, which led to changes in ocean temperatures and chemistry that significantly affected marine life. Sea levels rose and fell several times due to changes in the amount of ice in the polar ice caps and the movement of tectonic plates. These fluctuations affected the distribution of the marine environment and the availability of living marine resources.
- Is it impact on other organism?
- The greenhouse effect cause the warming of the Ocean. During the Cretaceous, tropical water temperatures ranged between 28 to 44 degree Celsius. At 30-degree latitude, ocean temperatures fell to 20 degrees Celsius. At 60-degree latitude, ocean temperatures are 12 degree Celsius, and at 90-degree latitude, temperatures are 4.5 degree Celsius. Therefore, polar temperatures are cold but cannot cause freezing.
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