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By comparison, the term paraphyly, or paraphyletic, uses the ancient Greek prefix παρά (pará), meaning "beside, near", [4] [5] and refers to the situation in which one or several monophyletic subgroups are left apart from all other descendants of a unique common ancestor. That is, a paraphyletic group is nearly monophyletic, hence the ...
The term paraphyly, or paraphyletic, derives from the two Ancient Greek words παρά (pará), meaning "beside, near", and φῦλον (phûlon), meaning "genus, species", [2] [3] and refers to the situation in which one or several monophyletic subgroups of organisms (e.g., genera, species) are left apart from all other descendants of a unique common ancestor.
In biological phylogenetics, a clade (from Ancient Greek κλάδος (kládos) 'branch'), also known as a monophyletic group or natural group, [1] is a grouping of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. [2]
Again, while not disagreeing with the notion that only monophyletic groups should be named, empiricist systematists counter this ancestry essentialism by pointing out that pelycosaurs are recognized as paraphyletic precisely because they exhibit a combination of synapomorphies and symplesiomorphies indicating that some of them are more closely ...
Cladogram (family tree) of a biological group. The green box (central) may represent an evolutionary grade (paraphyletic), a group united by conservative anatomical and physiological traits rather than phylogeny. The flanking red and blue boxes are clades (i.e., complete monophyletic subtrees).
While paraphyletic assemblages are popular among paleontologists and evolutionary taxonomists, cladists do not recognize paraphyletic assemblages as having any formal information content – they are merely parts of clades. Polyphyly: A polyphyletic assemblage is one which is neither monophyletic nor paraphyletic.
A taxon is called monophyletic if it includes all the descendants of an ancestral form. [61] [62] Groups that have descendant groups removed from them are termed paraphyletic, [61] while groups representing more than one branch from the tree of life are called polyphyletic.
A stem group is a paraphyletic assemblage composed of the members of a pan-group or total group, above, minus the crown group itself (and therefore minus all living members of the pan-group). This leaves primitive relatives of the crown groups , back along the phylogenetic line to (but not including) the last common ancestor of the crown group ...