Paleonet: first and last things

[anthony.butcher at port.ac.uk]

Dear all,

Apologies if what I mention below has already been covered, but I've been rather slow 
in posting on this topic!  Tony.


Salvador (1994, p. 57), as stated in previous posts, suggested the terms 'highest 
stratigraphic occurrence' and 'lowest stratigraphic occurrence' of a specified taxon. 

Rawson et al. (2002, p. 19), in the Geological Society's Professional Handbooks series, 
suggested the terms 'first (evolutionary) occurrences (FO)' and 'last (evolutionary) 
occurences (LO)'.  They did, however, recognise that this terminology may not be accurate 
when working in drill holes, as first occurrences may be affected by cavings.  They stated 
that, in these instances, '...it is recommended that the terms First Downhole Occurrence 
(FDO) and Last Downhole Occurrence (LDO) alone be used.'  

It therefore appears that to be scientifically accurate neither terminology can be forced 
into use in every instance, but rather a compromise should be sought.

As Salvador (1994) is the IUGS stratigraphical guide, I would personally recommend using 
HSO and LSO when working on sections and cores, as the terminology is entirely 
unambiguous in these instances.  For drillholes, I would recommend the use of FDO and 
LDO, as in the instance of drillholes they again are unambiguous, and do not imply a 
potentially incorrect stratigraphical postion.

Of course, this terminology will not appeal to everyone, but perhaps the most important point 
to come out of all this is that when any terminology or abbreviations are used in 
scientific literature, they must be explained thoroughly in the text, to avoid any 
ambiguity to the reader.  

However, the terms from the two references cited are perhaps most readily available to all 
biostratigraphers, being general works on stratigraphical procedure.  From experience, 
workers in particular areas or on specific taxa tend to follow certain conventions (perhaps to 
conform with previous literature/projects), whereas a common, simple, unambiguous 
terminology such as that suggested here would surely be beneficial to all.


PLEASE NOTE: I am not in anyway eminent or all-powerful, so this is purely my 
personal opinion, and should not be misconstrued as direct orders (which would 
definitely open up a whole can of worms here on Paleonet!  ;o)


REFERENCES:
RAWSON,P. F. et al. 2002. Stratigraphical Procedure. Geological Society Professional Handbooks, London, 58pp.

SALVADOR,A. (ed.). 1994. International Stratigraphic Guide (Second Edition).  International Union of Geological 
    Sciences, Trondheim, Norway, and The 	Geological Society of America, Boulder, Colorado, 1-214.

___________________________________

Dr Anthony Butcher
Palynologist
School of Earth & Environmental Sciences
University of Portsmouth
Burnaby Building
Burnaby Road
Portsmouth
PO1 3QL
United kingdom
Tel:  (+44) 23 9284 2258
Fax: (+44) 23 9284 2244
anthony.butcher at port.ac.uk
___________________________________
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