THE CAMBRIAN "EXPLOSION" WASNT SO EXPLOSIVE

@ossobuco,

I didnt hve a clue to which post you were referring. I see.

@farmerman,

http://upload.wikimedia.org/wikipedia/commons/thumb/f/fb/DickinsoniaCostata.jpg/220px-DickinsoniaCostata.jpg

dickensonia costata is a sort of "quilted" fossil with a possible notochord that seems to have derived from several lower Dickensonia forms of 20 million years earlier .D cotata is a card carrying mmember of the elite EDIACARAN faunal assemblage and a member of the Cambrian exudation

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It shouldn't be a surprise to anyone that there are fewer fossils of soft bodies creatures than there of "hard" bodied creatures, right?

And it also shouldn't be surprising that there were more soft bodied creatures the further back in time we go.

It seems to me that based on those two items alone it also shouldn't be too surprising that the Cambrian would "appear" to be an "explosion". If for no other reason than simply by virtue of an emergence of hard bodied creatures and a disproportionate likelihood of fossilization occurring.

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@rosborne979,

well thats what the original "explosion" was predicated on. Cept now, it appears that the rise of "Ahrd bodies" was extending beyond a reasonable time that anyone could call an "explosion' Guys who coin these terms cant realize beyond their own need for cleverness that other guys like Gungasnake and several of the more Conservative Christians would run with the clever phrase as an aphorism from their own limited bag-o-science

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Is it this?

http://palaeos.com/metazoa/ecdysozoa/panarthropoda/images/Hallucinogenia-Wonderful_Life.jpg

Or this

http://paleobiology.si.edu/burgess/imgBurgess/hallucigeniaD1.gif

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@panzade,

I would bet on the spines being on the back for defense, rather than as "stilt-legs".

Also the Hallucigenia is now though to be a possible ancestor to the Onychophora line (which have tube-feet).

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@rosborne979,

well someone revived this thread.

Here's an example of a "velvet worm" (PERIPATUS), one of the onycophorans . We used to see these in the rain forests and some of the indigenous people would use em for medicinal purposes. I forget how because I was told they had a poisonous skin.

http://upload.wikimedia.org/wikipedia/commons/6/67/Euperipatoides_kanangrensis_crop.jpg

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@farmerman,

farmerman wrote:

...medicinal purposes. I forget how because I was told they had a poisonous skin.

A lot of poisons have medicinal value when used in small quantities.

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@rosborne979,

riiggghhht, you first.

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@farmerman,

farmerman wrote:

riiggghhht, you first.

Kurare is used in modern medicine and so it Tetrodotoxin. Proper medical supervision required of course Smile

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@rosborne979,

Them worms would clatter under palm fronds we laid down as floors, and you could hear em walk around and the suckers were 8" long. They kill their prey by an evolved proboscis and a radula that allows them to inject a "tenderizing fluid" into their prey and they suck em dry like a spider.

The ones in Nigeria were actually cool looking, they were a nice blue color and would walk like a millipede.
Still kinda freaked me out and Ive eaten toated locusts.

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@farmerman,

I've never seen a Velvet Worm (Onychophoran), but I would like to some day. I wasn't aware they got to be 8" long. I've also read that they can shoot some type of sticky goo out of their mouths for catching their prey.

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@farmerman,

Quote:

well someone revived this thread.

I did it because I'm reading about the discoveries by Walcott near Mount Burgess. The detail of soft tissue is remarkable.

This picture fascinates me.

http://images.sciencedaily.com/2008/02/080219095801.jpg

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@panzade,

I'm fascinated by the cambrian environment as well. There are so many unusual creatures which we don't have around any more, and many of them look so alien. Yet you can still see remnants of the physiology yet to evolve in many of them. It's very cool.

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@rosborne979,

There was one specimen in particular that Walcot mis-categorized.
It was found in four sections and he thought it was four different creatures.
Later it was found to be one. Wish I could remember its name.

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@panzade,

There was a story about one named Opabinia, three different guys had three different drawings an conclusions and Walcott had two of his own.
Its not uncommon, lots of these fossils are smashed all to **** nd rolled around to be almost indistinguishable from flotsam.

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@panzade,

Quote:

I did it because I'm reading about the discoveries by Walcott near Mount Burgess

Which one you reading? Gould?

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@farmerman,

Following up Gould with
Crucible of Creation:
The Burgess Shale and the Rise of Animals

by Simon Conway Morris

Basically Gould posits that if evolutionary history was replayed things would come out differently.
Morris argues the opposite.

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@farmerman,

That be the one. Fascinating

http://cambrian-cafe.up.n.seesaa.net/cambrian-cafe/image/opabinia_2010.jpg?d=a2

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@panzade,

I read Crucibles shortly after it came out. I was aware of his arguments with Dawkins and Gould both, (but Im not certin why he has problems with Gould since his work on convergency is (was) very close to Goulds heart. (Goulds own concept of convergent "spandrels" owes a lot to Conway Morris

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THE CAMBRIAN "EXPLOSION" WASNT SO EXPLOSIVE

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