II am saying we came can hope (sometimes reasonably, sometimes forlornly) to distinguish dinosaur species; but that to to think we can say with any certainty which species belong in a given higher grouping is a fool's game. Many decades of experience have taught us this. Even if "genus" actually meant anything (which it doesn't), trying to assign species to them would be as error-prone as drawing any other kind of phylogenetic conclusion. And since genera alone contribute to what a species is _called_, it's sensible just to leave them out of the equation completely. (For other kinds of zoological taxonomists, e.g. extant malacologists, this may not be so; but I am not concerned with them.)
Exactly. "Galeamopus hayi" is a different name from "Diplodocus hayi", but they are both names for the same animal. This is unhelpful: ideal names are bijective (i.e. each taxon has one name and each name refers to one taxon). By having guessed that the species "hayi" belongs to the genus "Dipldocus", Holland (1924) put us in a position where we would have the change the name of his species. Now we needn't be too critical of what he did a century ago; but we also needn't copy his mistake.
-- Mike.