Session 5 in a series of internal Masterclass talks by Prof. Adrian Thomas from Animal Dynamics and Department of Zoology, University of Oxford. Skeleton space represents the ‘Periodic Table’ of the elements of skeletons. Evolution discovered all elements of Skeleton Space within the first few million years of the Cambrian Explosion, 540 million years ago. Hydrostatic skeletons (BDWHZYR) are everywhere in biology and hardly anywhere in engineering (except paraglider wings). Why?