Rigel is a B8 class star which means it is very large, very hot and very young by comparison to other stars. It is virtualy impossible to age a specific star. This is usually done by aging star clusters, a much more accurate method. Rigel is estimated as being 17 times as heavy as the sun and through a standard formula should have a main sequence lifetime of 8 million years (very short) which means it is less than 8 million years old. It wasn't there when the dinosaurs were there.
The formula is (mass of earth / mass of other sun)^2.5 * 10 Billion years
The formula isn't perfect - there are other factors but this is a good guess.