Sections through tough wombat femur show possible adaptation to digging.

Wombats are marsupial mammals that are only found in Australia. They are fossorial and dig out extensive networks of burrows. Wombats have a variety of adaptations to this lifestyle, which is energetically demanding and unusual in marsupials, including a  unique backwards-facing pouch to prevent young being smothered with dirt while digging. This lovely section, which represents a…