Geologic Time Scales
Dating from 544-505mya, the Cambrian Period began with what has been called a "Cambrian Explosion" for the large diversity in animals seen over such a geologically short period in time. Latter seen to have been a slower evolving process than it was once thought to be, the fossils of the Burgess Shale still show a the development of vastly more complex organisms than was seen before. Animals evolved the ability to swim and crawl, developed more acute senses of smell and taste. The sense of sight appeared With a the small beginning of just sensing changes in light, sight became so useful in detecting a swimming predatory moving over head, that vision soon pushed the evolution of many different organisms. Trilobites, ahead of their time, developed vision as advanced as the best insect sight of today.