plesiomorphy


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Related to plesiomorphy: Cladistic analysis, Plesiomorphic

ple·si·o·mor·phy

 (plē′sē-ə-môr′fē, plē′zē-)
n. pl. ple·si·o·mor·phies
An evolved character or trait that is shared by some or all members of a phylogenetic group and their common ancestor but is not unique to that group. A segmented spinal column is a plesiomorphy of mammals, being present as well in other groups such as fishes, reptiles, amphibians, and birds.

[Greek plēsios, near to; see pel- in Indo-European roots + -morphy.]

ple′si·o·mor′phic adj.
References in periodicals archive ?
1999, 2002), it may be questioned whether these stylocellid (and pettalidid) eyes are displaced median eyes or whether they are true lateral eyes retained only in these groups (Stylocellidae and Pettalidae) as a plesiomorphy (Shear 1993b; Giribet et al.
likely to be a plesiomorphy of many early eudicots and early
Concluding that the dicotyledonous embryo is a plesiomorphy among seed plants implies that the monocotyledonous embryo of monocots is a distinctive autapomorphy for this class of angiosperms.