Replies to This Discussion

Permalink Reply by Steph S. on December 14, 2012 at 7:26am

Thanks for the link to the article. Great discussion.

Permalink Reply by John Jubinsky on December 14, 2012 at 2:10pm

Below is an interesting part of the article coming from a somewhat skeptical colleague. One of them seems to be wrong about the nature of the sediment that the species was found in.

 

"To me the evidence is not a slam-dunk," says Shuhai Xiao, at Virginia Tech. He argues, among other things, that the same Ediacaran species found in what is arguably soil is also found in deposits that he says were ocean sediments. That would imply that the same species would be able to live both on dry land and under a salty ocean. Xiao finds that unlikely. "It's pretty hard for the same species to be able to live in both environments."

Permalink Reply by Joan Denoo on December 14, 2012 at 4:56pm

One of the reasons I like science is it formulates new and sometimes outrageous hypothesis of how the universe and all its inhabitants came to live on the Earth and everyone and anyone can challenge those  ideas, trying to blow holes in them or put stronger foundations under them.

Hypotheses stand as theories until other hair-brained schemes comes along, get challenged and either die, change the original idea or throw the original on the trash heaps of faulty ideas. There are no authorities. There is no one who has the power to declare "true" or "false". All ideas have to stand up to tough scrutiny. There is no shame or fear or guilt with holding to an idea that can be demonstrated to be out-of-date, unless they hold tightly to that belief when more evidence appears to give cause to change. The only certainty is change. 

As to this idea that life began on land should be relatively easy to accept or reject. Scientists who study geological and chronological settings of the Ediacaran forms may now have the tools to better interpret those Pre-Cambrian and Cambrian layers of strata. 

When living in central Texas, I went on many field trips with my geology classes and we found many Ediacaran fossils and they were recognized as fauna, not flora. They looked like plants, but were in fact animals. Ediacaran fossils have been found in nearly thirty localities on all six continents. 

Named for their most famous locality, the Ediacara Hills of southern Australia, the Ediacara biota first appeared in the late Neoproterozoic about 600 million years ago, and Ediacara-type fossils extend into the Cambrian. However, most Ediacaran organisms are between 565 and 541 million years old.

I found them in Pre-Cambrian and Cambrian strata and we class-members struggled at the realization they were of the animal kingdom, not the plant kingdom. We also observed animals in early layers of Cretaceous that look like and do, indeed, evolve into horseshoe crabs. I also found horseshoe crab on the coasts of Maryland, Delaware, New Jersey, New York.  

http://www.astrobio.net/exclusive/3341/fossils-on-the-edge-of-forever

The Cambrian explosion was the relatively rapid appearance, around 530 million years ago, of most major animal phyla, as demonstrated in the fossil record, accompanied by major diversification of organisms including animals, phytoplankton, and calcimicrobes.

 

Ediacaran fossils

Ediacaran life on land

The Ediacaran Assemblage

The Ediacaran Biotas in Space and Time

Permalink Reply by Bud the Wonderer on December 14, 2012 at 10:54pm

Joan Denoo said: "One of the reasons I like science is it formulates new and sometimes outrageous hypothesis of how the universe and all its inhabitants came to live on the Earth and everyone and anyone can challenge those ideas, trying to blow holes in them or put stronger foundations under them."

I know. I don't think it would even occur to believers to get together, and critically examine their beliefs. What is 'faith'? It's believing something because you'd really *like* for it to be true, despite no real evidence of its existance. It's emotional and subjective, and not the result of an objective study.

Permalink Reply by Joan Denoo on December 14, 2012 at 11:32pm

Some Ediacaran fossils looked like beautiful flowers and ferns even as they were animals.

Attachments:

• Ediacaran artist's drawing .jpg, 35 KB
• Ediacaran fossil .jpg, 90 KB

Permalink Reply by Idaho Spud on December 15, 2012 at 1:28pm

Interesting pictures & drawings Joan.  They reminded me that my mormon family members love collecting fossils, so it gave me the idea that maybe I should ask them how old they think their fossils are.

Permalink Reply by Joan Denoo on December 15, 2012 at 6:02pm

Spud, I am interested in their responses.