Cambrian Explosion Fossils

 

Fossils of the Cambrian Explosion Period for Sale

EDCOPE Enterprizes: Cambrian Explosion Fossils Chengjiang Maotianshan Shales Fossils

Terra Trilobites: Cambrian Explosion Fossils

About Cambrian Explosion Fossils

The Cambrian explosion can be characterized as the appearance in the fossil record of most major Phyla beginning some 530 million years ago. The appellation explosion is earned by the seemingly sudden appearance over a period spanning a meager several million years (actually estimates of duration range from 5 to 40 million years). This was a great worry to Darwin, who saw the rapidity as contrary to gradual evolution by means of natural selection. Mystery and controversy remains about the Cambrian explosion, and to a large degree is why the fossils of the period are a favorite at Fossil Mall.

Part of the mystery stems from whether there really was a rapid radiation into new complex forms, as compared to whether animals acquired new phenotypes aiding survival, such as numbers, size and hard parts that enabled a more robust fossil record to accrue. Much of what we know about the Cambrian explosion derives from fossils from the rare Cambrian lagerstätten sights where soft tissues are preserved. Most notable are the Burgess Shale of B.C. Canada and the considerably younger Chengjiang Maotianshan Shales of China, both containing highly diverse biota. Since Darwin’s time fossils of complex organisms of the Ediacaran Period dating to some 580 million years ago have been discovered extending the period of rapid diversification. Additionally, HOX genes that control much of an animal's basic body plan have been dated with molecular clock theory to the Precambrian. Regardless of whether the “explosion” took place in millions or tens of millions of years, the fossil record does show rapid diversification for which there are numerous explanatory theories. For example, the evolution of active predators in the late Precambrian could have spurred coevolution of hard parts on and larger size of other animals, in an offensive and defensive arms race below the seas. Hard parts fossilize much more readily than soft parts, leading to many more fossils but not necessarily more animals. Planktonic grazers began producing fecal pellets that fell to the bottom of the ocean rapidly, profoundly oxygenating the seas and providing the fuel that hungry predators needed to chase their prospective meals, or for the hunted to flee. The early Cambrian followed a period when earth was a snowball in space. Much life perished then. When the ice melted away, the surviving life had a milieu of genetic diversity, just the stuff on which selective pressures could act to create new and wonderful life forms. Maybe the secrets of the Cambrian rock record will never be entirely unlocked, leaving some Cambrian explosion mystery intact.