A new Late Devonian dipnoan from the Ketleri Formation of Latvia

Dipnoans (lungfishes) reached their peak of taxonomic diversity and morphological disparity during the Devonian Period, followed by a pronounced decline in both thereafter. The Late Devonian (Famennian) Ketleri Formation in Latvia has yielded several dipnoan fossils, including ?Conchodus sp., Dipterus sp., and Orlovichthys cf. limnatis, but these taxa remain poorly known and lack species-level diagnoses. New, distinct dipnoan material has been excavated from a new locality within the Ketleri Formation, Pavāri-2; although incomplete, it is represented by a very well-preserved and articulated palate and tooth plates and partial braincase. The new species Jumisodus latus, gen. et sp. nov. differs from all other Devonian dipnoans in its combination of an elongated bifurcated parasphenoid, a broad rhombic-shaped corpus which separates the pterygoids, and very wide tooth plates bearing cusps arranged in radial ridges. This unique character combination justifies the erection of a new taxon, although additional material is required for recovery of a precise phylogenetic position. A principal components analysis is used to assess the morphological disparity patterns among Paleozoic lungfishes based on their parasphenoid and tooth plate morphologies. The results highlight the transitional nature of J. latus, and other Famennian dipnoans, illuminating shared anatomical continuity across the Devonian–Carboniferous boundary.