Article: A near-tetrapod from the Baltic Middle Devonian

The tetrapodomorph sarcopterygian Livoniana multidentata gen. et sp. nov. is described on the basis oflower jaw fragments from the Middle Devonian (late Givetian) of Latvia and Estonia. It possesses a suite of derivedcharacters previously only known from tetrapods, which first appear in the late Devonian (late Frasnian), and aphylogenetic analysis places it on the internode between Panderichthys and the base of the Tetrapoda. The analysisalso reveals that the 'Elpistostegalia' are paraphyletic to Tetrapoda, with Elpistostege closer to tetrapods than isPanderichthys. Owing to incompleteness of the material, there is almost no overlap between the data sets forElpistostege and Livoniana; the analysis places the two genera in an unresolved trichotomy. In addition to the tetrapodfeatures, Livoniana has a strikingly autapomorphic dentary dentition comprising multiple tooth rows. It thus providesevidence both for the unexpectedly early evolution of tetrapod characteristics and for morphological radiation aroundthe fish-tetrapod transition.