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 100 micrometer slice through the femur of a wombat, shows the thick walls of the bone which strengthen it against the strain placed on the bones during digging. The bone is visualised under polarised light, and the different colours indicate the different orientations of collagen fibres in the bones. It is thought that the patterning of these fibres could indicate lifestyle and energetic differences when compared across marsupials, despite their relative evolutionary proximity.

Image courtesy of Timothy Bromage. See more of Timothy’s work here.

Femur: Thigh bone.

Fossorial: A burrowing or subterranean lifestyle.