Plesiomorphy
From Palaeos.org
(Redirected from Plesiomorphic)
Plesiomorphy, or Plesiomorphic trait: An ancestral or primitive character. Also called a primitive trait
A plesiomorphy of a smaller group is a synapomorphy of some larger group. For examples, the possession of jaws is plesiomorphic for mammals, but it's the defining synapomorphy of gnathostomes, a larger group that includes the mammals (along with most other vertebrates).
