Query: Hippopotamuses that are extinct
Domain: animals
Relevant documents:
Hippopotamus creutzburgi
Hippopotamus gorgops
Hippopotamus laloumena
Hippopotamus antiquus
Hippopotamus behemoth
Cyprus dwarf hippopotamus
Hippopotamus melitensis
Archaeopotamus
Hippopotamus pentlandi
Malagasy hippopotamus
Kenyapotamus
Hippopotamus madagascariensis