Re: paleonet 'Exceptional' preservation?

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Good to see all the interesting responses so far, and it's very 
interesting that the terrestrial record in particular seems to be much 
richer than I imagined. As extremes, from what little I know of Liaoning 
and the Argentine dinosaur beds, both have abundant unmineralised 
invertebrate remains that are effectively unstudied, because almost 
everyone wants the dinosaurs. I had thought that they were... well, 
exceptional.

  For Niko and Andy in particular, you are of course right that we have to 
be careful to define exceptionality relative to 'normal,' but there are 
some things that I think we would all argue are 'exceptional' in that they 
are (allegedly) rarely preserved. In a list of lability including 
protoplasm, internal organs, muscle, integument, unmineralised cuticle 
insect), lightly mineralised cuticle (some crustaceans), cellulose and 
shelly stuff, 'exceptional as a general term would probably fall around 
the insect-crustacean point. Of course, there is also the exceptional 
preservation of articulated skeletons, such as sponges and echinoderms, 
where effectively live burial is a pre-requisite. Although we will all 
have slightly different views, and there are other ways of judging 
exceptionality, what I'm asking about is whether our understanding the the 
distinction, as in the list above, is reasonable. From what Breandan, 
Judith... and, sorry, the other terrestrial palaeoecologist! - have been 
saying, there may be much more information there that is generally 
ignored. While not all squidgy things in a fauna are ever preserved, is 
there a small proportion that *are*, in almost every fauna?

It would also be interesting to hear from people who work on sites with 
definite 'soft tissue' preservation, as to the abundance of it, and 
whether their finds rely on good exposure of lots of fresh material. It's 
probably not a coincidence, I would guess, that so many of the classic 
Lagerstaetten are in major quarries. For example, the abundant 
preservation of truly labile tissues, such as cnidarians with tentacles, 
in pyrite (our 'biggest' discovery in the Builth area so far), is from a 
site that has been popular with palaeontologists for at least 70 years. I 
had myself been working there 10 years before even seeing the pyritised 
stuff. The reason? It appears to weather very quickly when exposed to 
Welsh weather. One specimen we left exposed as an experiment was 
unrecognisable after a week. (Anyone working on black shales with bits of 
weathered iron oxides, look very carefully indeed... ;-)

Joe 


> Well, I guess in a way all terrestrial forms are "exceptional" but some 
> are more exceptional than others. And those "some" might be, in the 
> main, inverts and plants. However muscle tissue preservation which I 
> have seen in dinos and fish are amazing but I guess the most amazing 
> that I have heard of is the recent finding of the tissue and cells in 
> T. rex. Wowie-zowie.
> 
> I think that Joe has given us the morals to this story which is that 
> (1) we must continually be on the lookout for these things and (2) it 
> helps if you are studying the deposit as a potential paleoecosystem 
> (taphonomy willing).
> 
> Judith,
> 
> judith harris
> emerita professor
> university of colorado museum
> 
> On Apr 7, 2005, at 2:45 PM, Cary Easterday wrote:
> 
> > Hi all,
> >
> > As a terrestrial researcher, I wonder about the meaning of 
> > "exceptional" too.  Plant and insect fossils are MUCH more diverse and 
> > abundant than terrestrial vertebrates, yet there are many more 
> > vertebrate paleontologists than paleobotanists and paleoentomologists! 
> >  If we look at sheer numbers...maybe we should call vertebrate fossils 
> > "exceptional," eh?  ;)
> >
> > Best Regards,
> >
> > Cary R. Easterday
> > PhD student, Geology, Paleobiology, Terrestrial Ecosystems, 
> > Geoarthropods, Biostatistics
> > Department of Earth and Environmental Sciences
> > University of Illinois at Chicago
> > 845 West Taylor Street, Room 2440
> > Chicago, IL 60607
> >
> > ceaste2@uic.edu
> > phone: 708.707.1030     fax: 312.413.2279
> >
> > Geological Society of America, Geobiology & Geomicrobiology Division, 
> > Limnogeology Division
> > Entomological Society of America
> > Paleontological Society
> >
> > Moderator
> > http://groups.yahoo.com/group/paleogeoarthropoda
> > http://groups.yahoo.com/group/FossilBugz
> > http://groups.yahoo.com/group/Sciencehumor
> >
> > ----Original Message Follows----
> > From: Judith Harris <harrisj@cvn.com>
> > Reply-To: paleonet@nhm.ac.uk
> > To: paleonet@nhm.ac.uk
> > Subject: Re: paleonet 'Exceptional' preservation?
> > Date: Thu, 7 Apr 2005 11:27:33 -0600
> >
> > As a paleoecologist, I am excited to hear Joe's views about 
> > exceptional preservation. I work with the terrestrial (including 
> > freshwater) record. In going over my fieldwork in my mind, I believe 
> > that you are correct. Even in the terrestrial record where 
> > preservation is difficult, there are many occasions in which some 
> > fossils in the section are "exceptionally preserved" or at least that 
> > it seems like surprising that they are preserved at all. It is not the 
> > bones and the teeth but the roots, rootlets, trace fossils, seeds, 
> > insects, leaves, etc. I think that Joe might be right when he mentions 
> > that these may often be overlooked. As we paleoecologists look at the 
> > record, searching for something other than just the main systematic 
> > groups, we will begin to see more and more of this. Of course, T. rex 
> > blood cells and vessels are an extreme version of this.
> >
> > judith harris
> > emerita professor
> > university of colorado museum
> >
> >
> >
> 
> 


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