((period span|'''''Period name'''''))
((period span|Permian))
298.9 million years ago to 251.902 million years ago
The |round=
parameter will round off the number to that many decimal places. It doesn't currently round the error margins; to omit these, use ((period span/brief)).
If this template generates an expression error, it is because the period is missing from ((next period)) or ((period start)). Please go ahead and add it in the appropriate place (once you've checked your spelling!).
You must also add the period to ((period start error)), which contains the errors shown after the ± in the output of this template.
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