The Cambrian Period begins not long before the deposits at Qingjiang were laid down, and it begins with a “bang.” Previous to this period, large organisms — organisms larger than the period at the end of this sentence — are relatively rare. And many of those which have been discovered, like the Ediacaran fauna first found in Australia, which date to around 545 million years ago, remain largely mysterious both in determining how they lived and how they relate to modern organisms.
Then … bang! In a few million years at the beginning of the Cambrian, every major branch of life that exists today appears. Sponges. Jellyfish. Mollusks. Arthropods. Some of these ancestoral creatures look wildly different than their ancestors, and some of the creatures from these rare lagerstätte may not be related to anything still around, but this period seems to represent evolution at its most fecund, spinning of experiments at a blistering rate as the Earth turns from a place populated mainly by a soup of microscopic creatures, to one in which larger, more complex forms dominate the seas.
Assembling a full image of the tree of life will always remain impossible. Too much is invisible to us. Too much is never preserved. But sites like Qingjiang offer moments of startling clarity, a still image captured against the filmstrip of evolution, that stands out starkly from the grainy background and offers to answer questions that have puzzled scientists for decades.
Already the information from Qingjiang has put to bed speculation over the evolution of Ctenophores, the lovely “comb-jellies” whose iridescent forms are so often the stars of documentaries showcasing the inhabitants of the deep ocean. And the specimen seem to be indicating that some of those currently unrepresented “experiments” found in the Burgess were part of much larger and more diverse groups.
But perhaps the most interesting information in the published paper is an indication that Qingjiang is not one site. In fact, the fossils that have been recovered in only a few months of field work represent deposits that may be “widespread” around South China. Which indicates that our image of life in the early Cambrian may go from black and white to technicolor over the next few years.