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Message: <blockquote data-quote="l_raty" data-source="post: 3090491" data-attributes="member: 24811">The taxa that are included in the dataset are presumably just those for which a complete mitochondrial genome was available at the time of the analysis.They estimate a date for the origin of the crown-group, which means the date when the most recent common ancestor of all extant rallids occured. This is of course different from the date of origin of the pan group, which would be the date of the divergence between the rallid lineage and its extant sister group.Extant species are always (by definition of the term) all within the crown group of any taxon they belong to. The difference between crown and pan groups is only in which past taxa (either known from fossils, or just inferred to have existed from phylogenetic analyzes) are placed in the group together with these extant species.(To be complete: species that are part of the pan group but not of the crown group are typically called "stem species"; they are all extinct by definition; together they may be referred as forming "the stem group"--although a "group" so-defined is always paraphyletic, hence not a "natural group" in the cladistic sense.)Excluding Rallus from crown-group Rallidae is not possible: it is the type genus of the family, thus (unless you regard the family as invalid), it is a Rallidae by definition; and as it is extant, it is in the crown group of its family by definition. Porzana is extant as well, thus to exclude it from crown-group Rallidae would require to exclude it from the family--but no reasons exist to do this.</blockquote>

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