Question

describe cambrian period

Answer 1

The Cambrian explosion or Cambrian radiation was the relatively short span event, occurring approximately 541 million years ago in the Cambrian period, during which most major animal phyla appeared, as indicated by the fossil record. Lasting for about the next 20–25  million years, it resulted in the divergence of most modern metazoan phyla.  Additionally, the event was accompanied by major diversification of other organisms. Prior to the Cambrian explosion,  most organisms were simple, composed of individual cells occasionally organized into colonies. Over the following 70 to 80 million years, the rate of diversification accelerated by an order of magnitude and the diversity of life began to resemble that of today. Almost all present animal phyla appeared during this period.There is strong evidence for species of Cnidaria and Porifera existing in the Ediacaran and possible members of Porifera even before that during the Cryogenian. Bryozoans don't appear in the fossil record until after the Cambrian, in the Lower Ordovician