Stem tetrapoda

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Tiktaalik, a tetrapodomorph with wrists, straddles the fish-tetrapod divide

The Stem Tetrapoda are a

phylogeny rather than to traits as in traditional systematics. Thus, some finned sarcopterygians
are considered to be stem tetrapods.

Content of the group

Stem tetrapods are members of Tetrapodomorpha, the total group and clade that also includes their descendants, the crown tetrapods:[1]

The stem Tetrapoda encompass three distinct grades successively closer to crown group Tetrapoda:[2]

Both Ichthyostegalia and Labyrinthodontia constitute paraphyletic

Tetrapoda itself should be defined (i.e. as a crown group, or as an apomorphy-based group, using the limb with digits),[5] making the actual content of the group uncertain.[6][7][8]

References