Translating Stories of Life Forms Etched in Stone

[groovedaddy]

In 1909, Charles Walcott, a paleontologist and secretary of the Smithsonian Institution, discovered one of the greatest and most famous fossil troves high in the Canadian Rockies on Burgess Pass in British Columbia. The slabs of Burgess Shale that Walcott excavated contained the earliest known examples at the time of many major animal groups in the fossil record, in rocks that were about 505 million years old.

Walcott’s discovery was further evidence of the so-called Cambrian Explosion — the apparently abrupt appearance of complex animals in the fossil record within the Cambrian Period, from about 542 to 490 million years ago. Although not seen before on the scale documented in the Burgess Shale, the emergence of trilobites and other animals in the Cambrian was familiar to paleontologists, and had troubled Charles Darwin a great deal.

The difficulty posed by the Cambrian Explosion was that in Darwin’s day (and for many years after), no fossils were known in the enormous, older rock formations below those of the Cambrian. This was an extremely unsettling fact for his theory of evolution because complex animals should have been preceded in the fossil record by simpler forms.

In “On the Origin of Species,” Darwin posited that “during these vast, yet quite unknown, periods of time, the world swarmed with living creatures.” But he admitted candidly, “To the question why we do not find records of these vast primordial periods, I can give no satisfactory answer.”

http://www.nytimes.com/2010/07/27/science/27creatures.html?_r=1&th&emc=th

[dtexdem]

1. Hmm, in tracing Ediacarian lifeforms, we'll undoubtedly learn more about the history of ...

Republicans.

;-)

[FiveGoodMen]

2. Lest the 4-paragraph rule lead to misunderstandings of the article...

More:

"It took a very long time, and the searching of some of the most remote places on the planet — in the Australian Outback, the Namibian desert, the shores of Newfoundland and far northern Russia — but we now have fossil records from the time immediately preceding the Cambrian. The rocks reveal a world whose oceans were teeming with a variety of life forms, including primitive animals, which is certainly good news for Darwin.

Now, this once-worrisome gap in the fossil record is a period of intense interest to geologists as well as paleontologists. The former have even given it its own division in the geological timescale. The Ediacaran Period, from 635 to 542 million years ago, is the first new geological period to be named in more than a century. Moreover, geologists have developed some intriguing theories about how dramatic changes in the Earth’s climate and chemistry during the Ediacaran may have allowed for the evolution of animals."