Tetrabrachia is one of two branches of the Polypodia phylum.


Tetrabrachia first emerged around 4034ma when it diverged from the Sarcopodia branch. Around 4055ma, Tetrabrachia split into two branches: Tachypodia and Acanthopodia.

The defining trait of Tetrabrachia is the tagmosis of the first two segments in the ancestral Polypod body plan, creating an anterior tagma comprised of four arms used for feeding.


  • Despite technically first appearing in Part 3, Tetrabrachia was not officially named until Part 7.


Evolutionary Tree
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