(Chapter 4) Footnote 9:

On the nomenclature of the skeleton see Galen De anatomicis administrationibus 2.220-223, De ossibus ad tirones 2.734.8-10. The word, orig. meaning something dried up (<ske/llw= dry up, parch) or withered (like a mummy), is unattested in the modern sense before the first century BC (Philodemus De morte 30).