fossilesqueLiterally no help at all
trxxruraxvrArmadillos are mammals, so probably more like convergent evolution and not an ancestor
Glyptodon are mammels too, and a direct ancestor of armadillos! The -don in the name does imply dinosaur, so I can see why one would make the assumptuon.
The “don” suffix just means tooth, so it doesn’t necessarily have to do with dinosaurs; there are a number of mammalian genera that got it, like Smilodon, Daeodon, Dorudon, and Thrinaxodon