Cambrian

Fossil of plants, invertebrates, vertebrates, and trace fossils have been identified in Yellowstone National Park from more than 40 stratigraphic units spanning more than 540 million years from the Cambrian to the Cenozoic eras.

Research in the park by Charles Walcott on trilobites in the late 1800s provided the foundation for his theory of the “Cambrian Explosion,” a term he used to describe the relatively sudden appearance of complex multi-cellular life possessing “hard parts” such as phosphatic or calcitic exoskeletons.

The British researchers suggested that in order to determine the reasons behind the Cambrian Explosion, scientists need to take a more ‘holistic approach’ that encompass a range of factors.

Over the years there have been a number of theories about the Cambrian Explosion. The researchers said that those concepts, which fall into three main categories — geological, geochemical and biological — are separate and exclusive processes that also suggest a single cause of the explosion.