Re: pores

[Crpntr@ix.netcom.com (Kenneth Carpenter)]

You wrote: 

>
>
>> Neil Clark asked: 
>> 
>>  Does anyone know whether there is a 
>> >simple way of determining how many pores reach the outer 
>surface if 
>> >it is damaged?
>> 
>> Yes, you make what is called a tangential section.  See the article 
>on 
>> preparation of eggshell for study by Betty Quinn in the Pat Leiggi 
>and 
>> Peter May "Vertebrate Preparation" book by Cambridge University 
>Press 
>> (1994).
>> 
>
>Yes, but if you do a tangential slice, you still have the problem of 
not 
>knowing how many of the pores actually reach the surface of the egg. 
> Many of the pores do not reach the surface as they terminate 
>beneath the outer layer.  In tangential section I have counted over 
>2,000 pores per sq cm.  I am presuming that the outer layer is sawn 
>off during tangential section preparation, but also if the surface is 
>worn then the results would also be spurious.   I think that for 
>physiological studies you would need to use the number of pores 
>reaching the outer surface?
>
>Neil
>
>
>Neil Clark
>Curator of Palaeontology
>Hunterian Museum
>University of Glasgow
>email: NCLARK@museum.gla.ac.uk
>
>Mountains are found in erogenous zones.
>(Geological Howlers - ed. WDI Rolfe)
>
>
Grigorescu et al (1994) used tangential sections to map changes in pore 
diameter through the shell, inside to the surface (p.85).  And yes, you 
do need to know if the shell reaches the surface for paleophysiology 
studies.  The fact that you apparently don't have all pores 
reaching the surface suggests that you make have faveoloolithid or 
dictyoolithid eggs.

Grigorescu et al 1994, Late Maastrichtian dinosaur eggs from the Hateg 
Basin (Romania) IN Carpenter, K., Hirsch, K.F., and Horner, J. R. 
Dinosaur Eggs and Babies. Cambridge University Press, p.75-87.

Kenneth Carpenter