Dipnoan from the Upper Triassic of East Greenland and remarks about palaeobiogeography of Ptychoceratodus
Wojciech Pawłak, Mateusz Tałanda, Tomasz Sulej, Grzegorz Niedźwiedzki
Abstract
Here we present a description of the dipnoan remains collected from the middle to upper Norian (Upper Triassic) of Jameson Land, East Greenland. The specimens consist of isolated tooth plates and skull bones of Ptychoceratodus, the most complete Late Triassic dipnoan material from Greenland. This genus is reported for the first time from the Upper Triassic of Greenland. The studied material belongs to Ptychoceratodus rectangulus previously known from the middle-upper Norian of Germany. It fills the biogeographical gap between the records of the Germanic and the Jameson Land basins. A reconstruction of the skull roof is provided, based on isolated bones collected from the same bone-bed. Their good preservation enables recognition of the sensory line pits, arranged similarly as in the extant Protopterus, suggesting a comparable mode of life. This finding has implications for our understanding of the disparity in Ptychoceratodus dipnoans, as well as the morphology between closely related dipnoans of the Late Triassic ecosystems.