Dry Rot?

These images are scanned from another edition of Atlas to Alison's History of Europe, and show plate 49, the Siege of Saragossa.

This edition was printed from the same plates, but onto smaller sheets. At some date it was rebound, without the title page, using new endpapers. It was then attacked by some organism – fungal? – is this dry rot?

Most of the plates show severe damage, but this is among the worst. I disinfected my scanner after scanning it.

I have seen many forms of damage to books, but nothing else like this. Can dry rot attack a book?

You can click on these images to see larger versions.