Linked from
The 12 pages that link to Top quark, each with the reason it gives.
Standard ModelBroader topic: Its discovery completed the model’s predicted set of six quark flavors.
Charm quarkCompared with: It shares charm’s charge but decays before forming hadrons.
FermilabRelated: Fermilab's Tevatron experiments established the top quark's existence.
Up quarkCompared with: It shares the up-type charge while contrasting sharply in mass and lifetime.
TevatronBroader topic: CDF and DZero announced its discovery from Tevatron collision data in 1995.
Down quarkCompared with: It contrasts with the light down quark in both charge and mass.