Other celestial bodies have been attributed to many changes on earth. But some scientists believe that the events can be attributed to phenomena's on earth like volcanicity. But the new evidence has turned quite some heads with some very convincing evidence.
Dennis Kent, from Rutgers University, explains that glass like structures found while drilling in New York may have come from a comet striking the earth. The heat from the comet may have resulted in the formation of the glass.
The timing of the comet coincides with the rise of mammals almost perfectly. With no dominant species after the demise of the dinosaurs, another organism had to step up. The scientist believes that the comet strike heated the earth up, catalyzing a state of the earth more suitable to be inhabited by mammals.
"It got warm in a hurry. This suggests where it came from," said Prof Kent. "The glassy spherules don't demand a comet, rather than an asteroid, but the idea is attractive because of the increase in isotopically light carbon which acts as a greenhouse gas."
The impact also raised the amount of carbon dioxide on the surface of the earth. This also catalyzed the rise of temperature by almost 6 degrees over the 1000 year period.