Your answer is gravitational forces
A vigorous excersie that requires a lot of energy
The Devonian Period was part of the better known Paleozoic Period. Some scientist think it was 416 million years ago. It was the time of the great fish. It gets its name from when red rocks from Devon, England were also found in North America. It is believed that during this period parts of North America, Europe, Russia and Greenland crashed together making a new land mass. Scientists believe this period ended about 354 million years ago when land plants began to take over and much of what was an ocean disappeared.
