Cambrian explosion
A global megabias is one that occurs over the whole world, though not necessarily in all depositional environments. There are numerous documented examples of this, many of which concern the Cambrian explosion and the Ediacaran fauna, both divisive subjects within the paleobiological community. Darwin commented on the Cambrian explosion, it being a great problem in his eyes, and speculated that it may be due to an increased propensity for preservation in the Cambrian and a reduced potential beforehand.