If we're considering Europe, I have photos from the early '70s of some rather special species:- zebra duiker, mountain tapir, monkey-eating eagle (Philippine eagle), grey-necked
Picathartes (all Frankfurt), hairy-nosed wombat, Ruwenzori black and white colobus (Basle), southern elephant seal (Hanover & Munich), Tasmanian devil (Stuttgart), white-nosed saki (Cologne) and probably quite a few more that I have forgotten.
I now have all my slides in the same place as my scanner

I just need new software and plenty of time

(so don't hold your breath).
It is important to remember that we have had many gains as well as losses in UK zoos (and European ones too). I can remember that in the early '70s Regents Park had one bush dog, one maned wolf and one anoa, all of them were elderly and I remember thinking that I must try to photograph each of them because when they died I might never see those species in the UK again. I am so pleased that I was quite wrong.
Likewise at that time I never expected to see saki monkeys (bearded or white-faced), howler monkeys, sifaka, fossa, koala or aye-aye in British zoos
and I'd never even heard of gentle lemurs
Alan