So far my understanding of BAOs is that they are a relic of the old universe formed by the freezing of acoustic density waves in baryonic matter as the universe entered the recombination epoch. These oscillations can be used as a "standard ruler" for length scale, providing means to calculate Hubbles Constant.

I don't understand how this then links to evidence for dark matter.

Any help on this would be very much appreciated. Thanks :)

So far my understanding of BAOs is that they are a relic of the old universe formed by the freezing of acoustic density waves in baryonic matter as the universe entered the recombination epoch. These oscillations can be used as a "standard ruler" for length scale, providing means to calculate Hubbles Constant.

I don't understand how this then links to evidence for dark matter.

Any help on this would be very much appreciated. Thanks :)