Fossil records support the fact that dinosaurs dominated life on Earth for more than 150 million years. During their reign, other animals had little chance of flourishing. Then, 65 million years ago the dinosaurs vanished from Earth. Today, there is no clear answer why this happened although there are several hypotheses.
Here are two viewpoints as to why dinosaurs became extinct.
Viewpoint 1
Massive deposits of ancient lava have been found throughout the world telling us that on Earth, 65 million-years ago, massive volcanic eruptions were common. For over 500,000 years, massive lava flows filled Earth’s atmosphere with copious amounts of smoke and ash. Because of this, sunlight was prevented from reaching Earth’s surface. Temperatures on Earth dropped significantly. As the sunlight decreased, so did photosynthesis and then the producers that relied on the sun and photosynthesis to make food. Few species could escape the effects of a darkened sky and the huge loss of producers in food webs everywhere on Earth. Dinosaurs as well as many other species could not survive these changes on Earth and 70% of life on Earth died at this time.
Viewpoint 2
65-million-years ago a 10-kilometer asteroid struck Earth near the Yucatan Peninsula in Mexico. The force of the asteroid is estimated to have been equal to that of three hundred million atomic bombs. Earth’s atmosphere filled with gas and dust from the asteroid’s impact, as well as with ash and smoke from resulting forest fires. Temperatures on Earth, as well as available sunlight, dropped dramatically. Plant life died and, as a result of this, so did many other species on Earth. When the dust and ash settled, greenhouse gases, released as a result of the asteroid impact, caused temperatures to rise much higher than average temperatures of pre-impact Earth. This shift in climatic conditions eventually resulted in the extinction of over 70% of all the species once living on Earth.
In Viewpoint 1, what does the word copious most likely mean?
Responses
A horrifichorrific
B enormousenormous
C egregiousegregious
D negligible