The respiratory organs of eurypterids
Phillip L. Manning & Jason A. Dunlop*
Department of Earth Sciences, University of Sheffield, Dainton Building, Brookhill, Sheffield S3 7HF
*Department of Earth Sciences, University of Manchester, Manchester M13 9PL
Cuticle fragments from the Upper Silurian (Prídolí Series) of south Shropshire, England, are described and interpreted as the respiratory organs of eurypterids. These fragments, combined with whole body evidence, suggest a dual respiratory system: lamellate book-gills, homologous with those of modern xiphosurans and arachnid book lungs, and an additional Kiemenplatten on the true sternite, the roof of the branchial chamber. Kiemenplatten is used in preference to gill-tract, because it is a more neutral term without functional implications. Eurypterids may have been partially terrestrial: the Kiemenplatten is interpreted as an accessory aerial respiratory organ, most closely analogous to the branchial 'lungs' of certain terrestrial crabs. Cuticular projections from the Kiemenplatten are interpreted as having held a layer of water to keep the structure moist during excursions onto land. A new reconstruction of the eurypterid respiratory system is presented.
Palaeontology, 38, 287-297 (1995)
Author's comments:
The things we described as eurypterid book-gills have now also been found in a fossil scorpion. Either we've misinterpreted scorpion structures and assigned them to eurypterids, or both eurypterids and at least some Palaeozoic scorpions had identical lamellate respiratory organs.
So far 
people were interested in eurypterid respiration