The Proceedings of the Eighth International Conference on Creationism (2018)

Locality Stratigraphic unit Age Description Reference(s) Comments Eastern Greenland Kap Graah Group Devonian Two trackways of symmetrically arranged impressions without median traces. Friend et al. (1976) Friend et al. (1976) discussed but rejected a tetrapod interpretation. Lucas (2015) attributes the traces to an arthropod, probably Diplichnites . Orkney Islands Upper Old Red Sandstone Devonian Two parallel but separated marks with symmetrical lateral projections. Westoll (1937); Wilson et al. (1935) Leonardi (1987) attributed the trace to a rhipidistian fish. Rogers (1990) suggested an arthropod trackway. Lucas (2015) interprets it as a zosterophyll stem with attached sporangia. Genoa River, New South Wales, Australia Combyingbar Fm Frasnian Two trackways with alternating pattern, one with median drag impression. Manus (smaller) and pes (larger) with at least five digits. Leonardi (1987); Warren and Wakefield (1972); Young (2006) Pridmore (1995) and Lucas (2015) suggest the same animal moving at different speeds made the two trackways. Easter Ross, northern Scotland Upper Old Red Sandstone Givetian to Tournaisian Trackway with alternating impressions. Manus (smaller) and pes (larger). Rogers (1990) Clack (1997) and Lucas (2015) agree this is a tetrapod trackway but the stratigraphic age is uncertain. Valentia Island, southwestern Ireland Valentia Slate Fm Givetian to Famennian Long meandering trackway without median drag impression. Alternating pattern with 150 manus and pes impressions showing size differentiation. Stössel (1995); Stössel et al. (2016) Clack (1997) and Lucas (2015) agree that this is a tetrapod trackway. Tibagi, Paraná, Brazil Ponta Gross Fm Givetian or Lower Frasnian Single “left manus” track with four long, curved “digits”. Leonardi (1983) Roček and Rage (1994) noted some similarity to ophiuroid trace fossils. Lucas (2015) rejects tetrapod interpretation. Zachełmie Quarry, Poland Wojciechowice Fm Middle Eifelian Numerous trackways and isolated impressions, varying greatly in appearance. Niedźwiedzki et al. (2010); Narkiewicz and Narkiewicz (2015) Lucas (2015) regards these as fish feeding traces or nests. However, Qvarnström et al. (2018) have defended the tetrapod identification. Glenisla, Grampians Range, Australia Grampians Gp Lower Devonian or Upper Silurian Twenty-three impressions in a ladder-like pattern. Turner (1986); Warren et al. (1986); Warren (1991); Young (2006) Roček and Rage (1994) identified this as a “rhipidistian” trace lacking the median body drag. Gourmanis et al. (2003) attributed it to Diplichnites , an arthropod trackway. Clack (1997) and Lucas (2015) also reject tetrapod interpretation. non-marine paleoenvironment (rather than the marginal marine setting originally inferred). Other Devonian trackways have been incorrectly ascribed to tetrapods or their stratigraphic age is uncertain (Table 3). Wise (1995) defineda stratomorphic series as a sequenceof speciesor higher taxa in the fossil record, where each taxon is a morphological intermediate between the taxa stratigraphically below and above it. In the case of the Devonian fish-tetrapod series, the ‘least derived’ elpistostegid Panderichthys appears in the Givetian (Ahlberg et al. 2000), the ‘most derived’ elpistostegids Elpistostege and Tiktaalik in the Frasnian (Ahlberg et al. 2000; Daeschler et al. 2006) and the ichthyostegalians in the upper Frasnian (Ahlberg 1991; Ahlberg 1995; Ahlberg 1998). Despite some possibly conflicting data, such as the Zachełmie trackways in the Middle Devonian and the poorly-known taxon Livoniana , which seems ‘more derived’ than Panderichthys but is contemporary with it (Ahlberg et al. 2000), the agreement between phylogeny (inferred from morphology) and stratigraphy seems fairly robust and the fish-tetrapod series thus provides a good example of a stratomorphic series sensu Wise (1995). From an evolutionary perspective, this stratomorphic series is interpreted as an evolutionary sequence documenting the step-wise acquisition of key tetrapod characters during a major morphological transition (e.g. Blieck et al. 2010; Clack 2006; Clack 2009; Clack 2012). However, Garner (2003) highlighted a number of difficulties with the evolutionary interpretation and concluded that the Devonian tetrapodomorphs were morphological intermediates, Garner and Asher ◀ Devonian and Carboniferous tetrapodomorphs ▶ 2018 ICC 461 Table 3. Putative trackways of tetrapods in the Devonian. Eifelian and Givetian are subdivisions of the Middle Devonian, Frasnian and Famennian are subdivisions of the Upper Devonian, and Tournaisian is a subdivision of the Lower Carboniferous. Fm = Formation. Gp = Group. After Lucas (2015).