‘Big Bang’ of Species May Be Explained by Continental Shift

Credit: Ian Dalziel

By Kelly Dickerson

A sudden explosion of new life-forms hundreds of millions of years ago may have been triggered by a major tectonic shift, new research shows.

About 530 million years ago, the Cambrian explosion brought a surge in new species to Earth, including most modern animal groups. Recent studies suggest that, during the Cambrian explosion, life evolved about five times faster than it’s evolving today. The sudden increase in species is sometimes referred to as “Darwin’s dilemma” because, at face value, it seems to contradict Charles Darwin’s theory of gradual evolution.

Scientists are still unsure what caused the number of species to skyrocket in such a short period of time, but Ian Dalziel, a research professor at the University of Texas Institute for Geophysics, thinks part of the answer may lie in how the continents shifted.

Dalziel thinks the ancient continent Laurentia (present-day North America) remained attached to the fused supercontinent Gondwana longer than current reconstruction models suggest. Some current models suggest Laurentia had already broken off before the Cambrian period. Instead, Dalziel thinks a deep ocean developed between Laurentia and Gondwana during the early Cambrian period and that the tectonic shift and resulting ocean likely caused sea levels to rise.

 

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