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Definition of Clade (was Re: Kileskus and Proceratosauridae)

The term "clade," when first erected, was defined _explicitly_ to apply _only_ 
to monophyletic groups (Huxley, 1958, p. 27).  Hence, there is no such thing as 
a "paraphyletic clade" or a "polyphyletic clade."  There are certainly 
paraphyletic or polyphyletic _groups_, but they are not clades.

Huxley, J.H. 1958. Evolutionary processes and taxonomy with special reference 
to grades. Uppsala Universitets Arksskrift 1958:21-39.  

Jerry D. Harris
Director of Paleontology
Dixie State College
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