Opinions from F. P. Moreno and A. Mercerat 1891
- 'Brontornis belongs to Brontornithidae'
- 'Brontornithidae belongs to Stereornithes'
- 'Cathartes belongs to Cathartidae'
- 'Cathartes fossilis belongs to Cathartes'
- 'Cathartidae belongs to Accipitres'
- 'Darwinornis belongs to Darwinornithidae'
- 'Darwinornis copei belongs to Darwinornis'
- 'Darwinornis socialis belongs to Darwinornis'
- 'Darwinornis zitteli belongs to Darwinornis'
- 'Darwinornithidae belongs to Stereornithes'
- 'Dryornis belongs to Dryornithidae'
- 'Dryornis pampeanus belongs to Dryornis'
- 'Dryornithidae belongs to Stereornithes'
- 'Falconidae belongs to Accipitres'
- 'Foetopterus belongs to Falconidae'
- 'Foetopterus ambiguus belongs to Foetopterus'
- 'Lagopterus belongs to Falconidae'
- 'Lagopterus minutus belongs to Lagopterus'
- 'Mesembriornis belongs to Stereornithidae'
- 'Mesembriornis milneedwardsi belongs to Mesembriornis'
- 'Mesembriornis quatrefagesi belongs to Mesembriornis'
- 'Mesembriornis quatrefragesi belongs to Mesembriornis'
- 'Mesembriornis studeri belongs to Mesembriornis'
- 'Owenornis belongs to Darwinornithidae'
- 'Owenornis affinis belongs to Owenornis'
- 'Palaeociconia australis belongs to Palaeociconia'
- 'Palaeociconia cristata belongs to Palaeociconia'
- 'Palaeospheniscus belongs to Spheniscidae'
- 'Palaeospheniscus antarcticus belongs to Palaeospheniscus'
- 'Palaeospheniscus menzbieri belongs to Palaeospheniscus'
- 'Palaeospheniscus patagonicus belongs to Palaeospheniscus'
- 'Patagornis belongs to Stereornithidae'
- 'Patagornis bachmanni belongs to Patagornis'
- 'Patagornis lemoinei belongs to Patagornis'
- 'Patagornis marshi belongs to Patagornis'
- 'Phalacrocoracidae belongs to Steganopodes'
- 'Phalacrocorax belongs to Phalacrocoracidae'
- 'Phalacrocorax pampeanus belongs to Phalacrocorax'
- 'Phororhacos longissimus belongs to Phororhacos'
- 'Phorusrhacos is corrected as Phororhacos and belongs to Stereornithidae'
- 'Protorhea belongs to Rheidae'
- 'Protorhea azarae belongs to Protorhea'
- 'Psilopterus belongs to Cathartidae'
- 'Psilopterus australis belongs to Psilopterus'
- 'Psilopterus communis belongs to Psilopterus'
- 'Psilopterus intermedius belongs to Psilopterus'
- 'Rhea belongs to Rheidae'
- 'Rhea fossilis belongs to Rhea'
- 'Rhea pampeana belongs to Rhea'
- 'Rhea subpampeana belongs to Rhea'
- 'Rheidae belongs to Struthiones'
- 'Rostrornis belongs to Brontornithidae'
- 'Sarcoramphus is corrected as Sarcorhamphus and belongs to Cathartidae'
- 'Sarcorhamphus fossilis belongs to Sarcorhamphus'
- 'Spheniscidae belongs to Impennes'
- 'Stereornis belongs to Stereornithidae'
- 'Stereornis rollieri belongs to Stereornis'
- 'Stereornithes belongs to Aves'
- 'Stereornithidae belongs to Stereornithes'
- 'Struthiones belongs to Aves'