this tag backbone seems to be getting used for two different purposes:
- a line on the skin which appears over the spine, such as in post #4996386 . essentially the back equivalent of linea_alba.
- an exoskeleton spine such as in post #3334611 (which may be mechanical or organic)
for the exoskeleton case, i'm not sure if an umbrella tag is really necessary to cover the handful of cases where we already have tags such as mechanical_spine, spine and exoskeleton.
otherwise a tag such as
exospine may be appropriate. ideally something that's not easily confused with exposed_bone (
for the skin line case it seems highly under-tagged -- though if there's some other tag already for this, i haven't been able to find it.
i'd be in favour of moving these cases to a more specific tag. however i haven't been able to find the correct name for this anatomical feature -- some sources refer to it as the 'vertebral line'. if anyone knows the correct name that would be helpful.
whatever approach we take for those cases, i suggest we write a disambiguation wiki page for backbone.