Showing posts with label Burgess Shale. Show all posts
Showing posts with label Burgess Shale. Show all posts

Thursday, October 22, 2009

More on the Burgess Shale.

After my post on the work that is being done on the Burgess Shale, a reader wrote to accuse me of dishonesty in providing the story. I was going to reply within the comments section but the more I thought about it, the more I realized that it probably needs to be a post. This is what the reader wrote:
You didn't tell the whole truth. The Cambrian has starfish, jellyfish, sponges and clams to name a few have not change a bit in 530 million years.

The fact that some of the other species are now extinct is beside the point.

The argument by Creationists is that life sprang into existence! There is nothing that has been found in the pre-Cambrian that can explain the explosion of life in the Cambrian.

Why are Darwinians so dishonest?

Thanks for the article even though it is very misleading.
Dear reader, my point was not to say that there are some forms of life that have remained unchanged. My point was to show that the life in the Cambrian appears over the course of some 30-50 million years. This is not exactly springing into existence. As I mentioned in another post, to put this into perspective, 30-50 million years ago there were no whales, no bears, no modern cats, no modern dogs and no humans. In fact, humans aren't even recognizable 10 million years ago. 30-50 million years in geological terms is a short period. For biological organisms, it is a pile of years. As far as your argument that life "sprang into existence," lets see what Duane Gish has to say:
In the Cambrian geological strata there occurs a sudden, great outburst of fossils of animals on a highly developed level of complexity. In the Cambrian rocks are found billions of fossils of animals so complex that the evolutionists estimate they would have required one and a half billion years to evolve. Trilobites, brachiopods, sponges, corals, jellyfish, in fact every one of the major invertebrate forms of life are found in the Cambrian. What is found in rocks supposedly older than the Cambrian, that is in the so-called pre-Cambrian rocks? Not a single indisputable fossil! Certainly it can be said without fear of contradiction, the evolutionary predecessors of the Cambrian fauna have never been found.
Gish is absolutely incorrect about what is found in the pre-Cambrian rocks. There are extremely well-described fossils, many of which (but not all) can be shown to be ancestral to Cambrian forms. While it is true that Trilobites appear in the early Cambrian, they do not diversify into the nearly 17 000 species they eventually become until late in the Cambrian.

Regarding your comment about nothing being found in pre-Cambrian sediments that can explain the explosion of life in the Cambrian, I found over 1700 articles arguing to the contrary in one pass. Here is what just one, Peterson et al. (2008) has to say about it:
Despite the presence of many different stem-group taxa, the Ediacaran is still a transitional ecology, with these organisms confined to a two-dimensional mat world. This stands in dramatic contrast to the Early Cambrian where the multi-tiered food webs that so typify the Phanerozoic were established with the eumetazoan invasion of both the pelagos and the infaunal benthos (Butterfield 1997, 2001; Vannier & Chen 2000, 2005; Dzik 2005; Peterson et al. 2005; Vannier et al. 2007). Hence, although the Ediacaran is an apparent quantum leap in ecological complexity as compared with the ‘boring billions’ that characterize Earth before the Ediacaran, it is still relatively simple when compared with the Cambrian, yet another quantum leap in organismal and ecological evolution. Thus, the Ediacaran stands as the transition interval between the ‘Precambrian’ and the Phanerozoic.1
So the question I have to ask is, after reading the article about someone who is out in the field, actually examining the data, how can you accuse him of dishonesty? Furthermore, why would I believe someone who has never actually looked at the data over someone who is intimately involved with it and publishing about it? Now who is being dishonest?


1Peterson, K.J., Cotton J.A., Gehling, J.G. and Pisani, D. (2008) The Ediacaran emergence of bilaterians: congruence between the genetic and the geological fossil records. Phil. Trans. R. Soc. B 2008 363, 1435-1443

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Wednesday, October 21, 2009

Work at the Burgess Shale Formation

Siobhan Roberts of Smithsonian.com is reporting on work that is going on at the Burgess Shale formation in Canada. They write:

The Burgess Shale is Mecca for paleontologists. Charles Doolittle Walcott, the fourth Secretary of the Smithsonian Institution, discovered this rich fossil bed a century ago, in the summer of 1909, and named it for nearby Mount Burgess. At the end of his first field season here, Walcott wrote in a letter to a colleague that he had "found some very interesting things." Talk about understatement. The Burgess fossils tell nothing less than the story of the Cambrian explosion—evolution's Big Bang—when relatively simple organisms rapidly diversified into the sorts of animals that live today. The exquisitely preserved Burgess specimens (most likely entombed by underwater mudslides) include the remnants of soft-bodied organisms, which are rare in the fossil record. The animals inhabited the ocean floor 505 million years ago, near the end of the Cambrian Period.

"Most of the phyla we know today we can see already in the Cambrian and the animals of the Burgess Shale," said Caron. But the fossils still look very strange. "They certainly show evidence of evolution," Caron said. "The animals that you see there don't look like the ones we have today."

This is critical to an understanding of the Cambrian Explosion, that the animals alive during this time largely don't resemble animals alive today. How strange were they?
In 1989, paleontologist Stephen Jay Gould popularized Burgess' "weird wonders" in his bestselling book Wonderful Life. But he argued that Walcott [the discoverer of the formation] had erroneously shoehorned the fossils into existing taxonomic groups. He suggested that the curious "problematica" fossils that had long defied scientific identification—such as Hallucigenia, an inch-long creature with two rows of spines on its back—deserved their own taxonomic groupings.
Things to keep in mind the next time a creationist says that all of the modern phyla arrived fully formed at the beginning of the Cambrian.

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