-------------+---------------------+-------------------+-----+-----+----- Geological | Stem-Groups of | Living Relatives |Pale-|Onto-|Mor- Periods. | Ancestors. | of our Ancestors. |onto-|geny.|phol- | | |logy.| |logy. -------------+---------------------+-------------------+-----+-----+----- |{16. SELACHII |16. NOTIDANIDES | I | II | III Silurian |{ Primitive fishes| Chlamydoselachus| | | |{ _Proselachii_ | _Heptanchus_ | | | |{17. GANOIDES |17. ACCIPENSERIDES | II | I | II Silurian |{ Plated fishes | Sturgeon, | | | |{ _Proganoides_ | Polypterus | | | |{18. DIPNEUSTA |18. NEODIPNEUSTA | I | II | II Devonian |{ _Paladipneusta_ | Ceratodus, | | | |{ | Protopterus | | | |{19. AMPHIBIA |19. PHANEROBRANCHIA| III | III | III Carboniferous|{ _Stegocephala_ | and Salamandrina | | | |{ | (Proteus, Triton)| | | |{20. REPTILIA |20. RHYNCOCEPHALIA | III | II | II Permian |{ _Proreptilia_ | Primitive lizards| | | |{ | Hatteria | | | -------------+---------------------+-------------------+-----+-----+----- |{21. MONOTREMA |21. ORNITHODELPHIA | I | III | III Triassic |{ _Promammalia_ | Echnida | | | |{ | Ornithorhyncus | | | |{22. MARSUPIALIA |22. DIDELPHIA | I | II | II Jurassic |{ _Prodidelphia_ | Didelphys, | | | |{ | Perameles | | | |{23. MALLOTHERIA |23. INSECTIVORA | III | I | I Cretaceous |{ _Prochoriata_ | Erinaceida | | | |{ | (Ictopsida+) | | | -------------+---------------------+-------------------+-----+-----+----- |{24. LEMURAVIDA |24. PACHYLEMURES | III | I? | II Older Eocene |{ Earlier lemurs | (_Hypopsodus_+) | | | |{ Dent. 3, 1, 4, 3 | (_Adapis_+) | | | |{25. LEMUROGONA |25. AUTOLEMURES | II | I? | II Later Eocene |{ Later lemurs | (_Eulemur_) | | | |{ Dent. 2, 1, 4, 3 | (_Stenops_) | | | |{26. DYSMOPITHECA |26. PLATYRRHINÆ | I | I | II Oligocene |{ Western apes | (_Anthropops_+) | | | |{ Dent. 2, 1, 3, 3 | (_Homunculus_+) | | | |{27. CYNOPITHECA |27. PAPIOMORPHA | I | I | III