> Eudora
> Our Universe
> Galaxies
> Individual Galaxies
> Milky Way
> Spiral Arms of the Milky Way
> Orion–Cygnus Arm
> Individual Planetary & Star Systems in the Orion-Cygnus Arm
> Solar System
> Objects in the Solar System
> Planets of the Solar System
> Individual Planets in the Solar System
> Earth
> Chronology of Earth
> History of the Earth
> Evolution of Life
> Tree of Life on Earth
> Domains, Species Kingdoms etc.
> Node
> Eukaryota
> Unikonta
> Opisthokonta
> Holozoa
> Filozoa
> Node
> Animalia (syn. Metazoa)
> Eumetazoa
> Bilateria
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> Deuterostomia
> Node
> Chordata
> Node
> Craniata
> Vertebrata
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> Node
> Node
> Node
> Node
> Gnathostomata
> Eugnathostomata
> Teleostomi
> Osteichthyes
> Sarcopterygii
> Tetrapodomorpha
> Node
> Node
> Node
> Node
> Node
> Node
> Node
> Node
> Tetrapoda (Terrestrial Vertebrates)
> Node
> Node
> Node
> Node
> Node
> Node
> Node
> Node
> Crown Tetrapoda
> Reptiliomorpha
> Node
> Node
> Amniota
> Synapsida
> Pelycosauria
> Eupelycosauria
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> Sphenacodontia
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> Node
> Node
> Sphenacodontoidea
> Ctenorhynchus
> Sphenacodontidae
> Sphenacodontinae
Tetraceratopsidae
Steppesaurus. Outline of Steppesaurus maxilla with skull of Sphenacodon for comparison Steppesaurus is an extinct genus of pelycosaur belonging to the Sphenacodontidae family, related to Dimetrodon and Sphenacodon.
