In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of taxa which meets these criteria: the grouping contains its own most recent common ancestor, i.e. excludes non-descendants of that common ancestor the grouping contains all the descendants of that common ancestor, without exceptionMonophyly is contrasted with paraphyly and polyphyly as shown in the second diagram. Wikipedia