Editing Oracle bone (section)

=== Preparation ===
[[File:Chinese oracle bone (16th-10th C BC) - BL Or. 7694.jpg|thumb|Holes drilled into an oracle bone]]
The bones or shells were cleaned of meat and then prepared by sawing, scraping, smoothing, and even polishing to create flat surfaces.{{sfn|Xu|2002|p=24}}{{sfn|Keightley|1978a|pp=13–14}}{{efn|{{harvnb|Chou|1976|p=12}} notes that evidence of sawing is present on some oracle bones, and that the saws were likely made of bronze, although none have ever been found.}} The predominance of scapulae, and later of plastrons, is also thought to be related to their ease of use as large, flat surfaces that needed minimal preparation. There is also speculation that only female tortoise shells were used, as these are significantly less concave.{{sfn|Keightley|1978a|p=9}} Pits or hollows were then drilled or chiseled partway through the bone or shell in an orderly series. At least one such drill has been unearthed at Erligang, exactly matching the pits in size and shape.{{sfn|Keightley|1978a|p=18}} The shape of these pits evolved over time, and is an important indicator for dating the oracle bones within various sub-periods in the Shang dynasty. The shape and depth also helped determine the nature of the crack that would appear. The number of pits per bone or shell varied widely.