TETRAPOD TRACKWAYS FROM THE UPPER DEVONIAN ST. FINAN’S SANDSTONE FORMATION, SOUTHWEST KERRY, IRELAND

Tetrapod trackways are described for the first time from the Upper Devonian St. Finan’s Sandstone Formation at Tooreen in St. Finan’s Bay, southwest County Kerry. The St. Finan’s Sandstone Formation is a 1,240m thick sandstone-dominated sequence that occurs in the middle part of the continental Old Red Sandstone Munster Basin succession. The trackways comprise 140 imprints that show variable depth and shape. This variability is attributed to changes in the firmness of the substrate and water depth along the length of the trackways. One of the trackways preserves an imprint with possible five-digit impressions and another displays a tapered elongated depression that is tentatively interpreted as a tetrapod body impression. Analysis of three trackways indicates they were made by a population of similar-sized tetrapods (just under 1m in length) that moved by lateral sequence walking. The trackways are preserved in a current-rippled and parallel-laminated sandstone sequence that was deposited on a flood plain bordering a river channel margin. A spore assemblage obtained from a mudstone within the trackway-bearing sequence is assigned to the Rugospora bricei-Cymbosporites acanthaceus BA Biozone, which biostratigraphically dates the trackway as Upper Devonian (mid Frasnian) in age. The Tooreen tetrapod trackways are very similar in size, spatial arrangement and palaeoenvironment to those recorded from the older Middle Devonian (Givetian) Valentia Slate Formation that occur nearby on Valentia Island. This new evidence extends the geographic and geological range of these ichnological datasets and provides a better understanding of the early stages of colonisation of continental (terrestrial) environments by Devonian tetrapods.