Arachnid book-lungs (posted for P.Selden)

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To: paleonet-owner@nhm.ac.uk
From: Paul Selden <PSELDEN@fs2.ge.man.ac.uk>
Date: 23 Oct 1995 14:37:44 GMT
Subject: Arachnid book-lungs
Reply-to: pselden@fs2.ge.man.ac.uk
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Ian Stewart wrote:

>A subject which recently came up as part of a tea room
>debate....."Arachnids which came first book-lungs or book-gills"
>are there any discussions or relevant reviews on the above topic?
>I would welcome any comment.
>Ian.Stewart@sci.monash.edu.au
>
The simple answer is book-gills. The earliest arachnids are scorpions, and
these were aquatic in the
Silurian, at least, respiring by means of gills. Evidence suggests that, at
least in some scorpions,
book-gills were transformed into book-lungs (see the review Selden, P. A. &
Jeram, A. J. 1989.
Palaeophysiology of terrestrialisation in the Chelicerata. Transactions of
the Royal Society of
Edinburgh 80, 303-310). All other arachnid groups appear in the fossil
record with fully developed
book-lungs (where these can be seen), e.g. amongst the earliest land
animals for which we have body
fossil evidence are trigonotarbid arachnids with nice book-lungs. There is
no evidence for whether
these developed from book-gills, however.

Best wishes

Paul Selden---------------------------------
     Dr Paul A. Selden
     Senior Lecturer in Palaeontology
     Department of Earth Sciences
     University of Manchester
     Manchester M13 9PL
     United Kingdom

Tel: 0161 275 3296
Fax: 0161 275 3947
---------------------------------