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Earth's environment during the dinosaurian era was far different than it is today. The days were several minutes shorter than they are today because the gravitational pull of the sun and the moon have over time had a braking influence on Earth's rotation. Radiation from the Sun was not as strong as it is today because the Sun has been slowly brightening over time. Other changes in the environment may be linked to the atmosphere. Carbon dioxide, a gas that traps heat from the Sun in Earth's atmosphere—the so-called greenhouse effect—was several times more abundant in the air during the dinosaurian age. As a result, surface temperatures were warmer and no polar ice caps could form.
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The pattern of continents and oceans was also very different during the age of dinosaurs. At the beginning of the dinosaurian era, the continents were united into a gigantic supercontinent called Pangaea (all lands), and the oceans formed a vast world ocean called Panthalassa (all seas). About 200 million years ago, movements of Earth's crust caused the supercontinent to begin slowly separating into northern and southern continental blocks, which broke apart further into the modern continents by the end of the dinosaurian era.
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