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Walt

"It seems likely that trilobites were preceded by soft-bodied ancestors: at several localities, sedimentary rocks with trace fossils of trilobite activity underlie the oldest rocks with trilobite body fossils." 

From http://www.ucmp.berkeley.edu/arthropoda/trilobita/trilobitafr.html

 

Hello all,

I'm looking for papers that support or dispute the above standard line about trilobite ancestors likely having soft bodies. 

 

I searched the forum but tags such as "soft body" produces papers that refer to the soft bits of hard bodied trilobites; not true soft bodied trilobites.  One or two papers, if you know of any, would be sufficient to get me on my way.

 

Also, if anyone has thoughts about this subject, I would love to hear them.  It is bothersome (at least to me) that these creatures seem to have no connection to the Proterozoic.  

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ynot

It is My understanding that annelid worms are considered to be the ancestors of trilobites, but I can not site any papers on the subject.

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Walt
7 minutes ago, piranha said:

A lot of Cambrian organisms have no apparent ancestors from the Proterozoic, but they certainly did exist

Yes, most certainly they did. 

I find the beginning of the trilobite story as fascinating as most people find the end.

As always, thanks for the info!  

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piranha
4 minutes ago, FossilDAWG said:

...and their relatively sudden appearance gives the illusion of the "Cambrian explosion".

 

 

or an alternative turn of phrase: "Cambrian Explosion Illusion" :P

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Walt

 

24 minutes ago, FossilDAWG said:

their relatively sudden appearance gives the illusion of the "Cambrian explosion".  In reality a huge diversity of phyla, classes, orders etc were in existence for perhaps hundreds of millions of years before the Cambrian explosion.

Thank you, Don. 

I tend to lose sight of just how much time we are dealing with here. 

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Walt

SPRIGGINA IS A TRILOBITOID ECDYSOZOAN

 

A pretty definitive statement.

This is from a presentation at the 2003 GSA conference.  Does anyone know if it was from a published paper?  I have searched the author but found no papers that seem to support his assertion.

Spriggina_is_a_trilobitoid_ecdysozoan.pdf

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Kane
2 minutes ago, Walt said:

SPRIGGINA IS A TRILOBITOID ECDYSOZOAN

 

A pretty definitive statement.

This is from a presentation at the 2003 GSA conference.  Does anyone know if it was from a published paper?  I have searched the author but found no papers that seem to support his assertion.

Spriggina_is_a_trilobitoid_ecdysozoan.pdf

I believe the author makes the claim in his 2000 book, The Garden of Ediacara: Discovering the First Complex Life (Columbia UP).

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Kane

The section most pertinent would be starting on page 34, "Spriggina and the Soft-Bodied Trilobite" where he covers some of the backstory controversy. Very interesting reading.

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piranha
2 hours ago, Walt said:

SPRIGGINA IS A TRILOBITOID ECDYSOZOAN

A pretty definitive statement.

This is from a presentation at the 2003 GSA conference. 

 

 

As I mentioned above, the proto-trilobite theory for Spriggina is widely panned nowadays.  Spriggina does not have bilateral symmetry and remains an enigma to Ediacaran workers to this day.

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FossilDAWG

The author is known for other controversial hypotheses as well.  For example, he has published a hypothesis that the ichthyosaur bones at Berlin-Ichthyosaur State Park (in Nevada) are evidence of a Triassic giant cephalopod (kraken) that killed the ichthyosaurs and arranged the bones.

 

He has also suggested that the Cambrian trace fossil Paleodictyon is the nest of an unknown animal.  This would be 200 million years older than the oldest generally accepted nest trace fossil.

 

On the other hand he is apparently credited with naming the Precambrian supercontinent Rodinia.

 

Don

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Walt
2 minutes ago, piranha said:

 

 

As I mentioned above, the proto-trilobite theory for Spriggina is widely panned nowadays.  Spriggina does not have bilateral symmetry and remains an enigma to Ediacaran workers to this day.

Thank you.

Please understand that every question I have answered on here generates a 100 more in my head.  I wish the subject was more linear, and perhaps in a classroom it is, but for me it is a twisting and tangled path of competing theories and nearly incomprehensible scientific jargon.  (which I am gladly learning)

Some of my questions are elementary and tiring, I'm sure.  But I do try and find the answers on my own before posting.  And to understand why this theory, for example, is widely panned, I have to look at all sides of the subject.  

I will also say that it is a shame so many scientific papers are locked away from folks such as myself.  That is why I appreciate you and TFF so much.  

 

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Kane

And there is certainly no harm in reading widely. :) Even discredited works have a value (if perhaps to help better determine the wheat from the chaff!). History has produced some great minds that do sometimes deviate into wild speculation or unhealthy obsessions. For example, the bulk of Newton's writings were on alchemy, and Georg Cantor (who pioneered set theory and the continuum hypothesis) spent a bit too much of his time subscribing to the Baconian theory of Shakespearian authorship. 

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Walt
7 minutes ago, FossilDAWG said:

The author is known for other controversial hypotheses as well.  For example, he has published a hypothesis that the ichthyosaur bones at Berlin-Ichthyosaur State Park (in Nevada) are evidence of a Triassic giant cephalopod (kraken) that killed the ichthyosaurs and arranged the bones.

 

He has also suggested that the Cambrian trace fossil Paleodictyon is the nest of an unknown animal.  This would be 200 million years older than the oldest generally accepted nest trace fossil.

 

On the other hand he is apparently credited with naming the Precambrian supercontinent Rodinia.

 

Don

You know, I was going to ask about his reputation....when I googled him in Scholar he is all over the place with the subjects of his papers.

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