Terrestrial trace fossils from the Lower Old Red Sandstone, southwest Wales

Abstract

An assemblage of terrestrial trace fossils is described from the Lower Old Red Sandstone of Pembrokeshire, southwest Wales, preserved in mainly fine-grained alluvial facies (channel and overbank sediments, deposited by predominantly ephemeral flows within a semi-arid environment), and thin tuffaceous horizons. The ichnofauna is dominated by an extensive, but low diversity Beaconites ichnocoenosis, comprising the meniscate backfilled burrow Beaconites barretti. Concentrations of these burrows (up to 30 per square metre) show normal size distributions, representing periodic colonization events (inferred as a response to seasonal desiccation) of subaerially exposed (partly indurated) sediments, probably by a population of eoarthropleurid myriapods penetrating the substrate to the level of the water table in order to aestivate and/or moult. Arthropod trackways also characterize an active arthropod epifauna of arachnids (Paleohelcura; first Welsh record) and myriapods (two forms of Diplichnites up to 160 mm wide) and Diplopodichnus. Additional ichnotaxa include arthropod foraging and resting traces (bilobed trails, Tumblagoodichnus and Selenichnites), 'scratch arrays' and worm burrows (Cochlichnus, and Palaeophycus) and faecal pellets all representative of the Scoyenia ichnofacies.

The Ridgeway Conglomerate Formation of SW Wales, and its implications. The end of the Lower Old Red Sandstone?

“…The latter is dominated by inclined (IHS) and non-inclined heterolithic sediments with multiple calcrete profiles (Allen and Williams 1978), the style of sedimentation being similar in the fine-grained units of both formations. Further evidence linking the RCF to the FWF is given by the local abundance of Beaconites barretti burrows within both formations (this study; Morrissey and Braddy 2004). By comparison, only one example is seen in the Cosheston Group (Thomas et al 2006), and their occurrence is very rare within the correlative Senni and Brownstones formations elsewhere within the Anglo-Welsh Basin (Morrissey 2006).…”

Age of the peel sandstone group, isle of man

“…Occurrences of Beaconites and Diplichnites, both common Devonian ichnogenera (Buatois et al 1998), are particularly indicative of the ORS. Although a Scoyenia-type ichnofauna cannot be used uncritically for stratigraphic interpretation, the association of ichnotaxa invites direct comparison with identical assemblages reported from the Lower ORS of the Anglo-Welsh Basin (Morrissey and Braddy 2004) and the Midland Valley of Scotland (Pollard and Walker 1984), and suggests a similar latest Silurian to Early Devonian age for the Peel Sandstone Group.…”

“…Examples occur in sandy, alluvial fan channel deposits (Facies Association 4), and are also observed to penetrate the tops of sand-dominated fluvial channel sandstones (Facies Associations 1 and 2). The burrows are interpreted as aestivation chambers of eoarthropleurid myriapods that penetrated sediment to the level of the water table during seasonal aridity (Morrissey and Braddy 2004). Other traces associated with B. barretti include small deposit-feeding burrows (B. antarcticus) and U-shaped dwelling burrows (Diplocraterion parallelum).…”

Archetypally Siluro-Devonian ichnofauna in the Cowie Formation, Scotland: implications for the myriapod fossil record and Highland Boundary Fault Movement

“…Meniscate burrows reported from the mid-Silurian Grampians Group of Western Australia probably formed in a fully marine setting (George, 1994;contra Gouramanis et al, 2003). Elsewhere (2000), Gand et al (1997), Germs (1972), Goldring and Pollard (1995), Graham and Pollard (1982), Hakes (1976), Han and Pickerill (1994), Häntzschel (1975), Hunter and Lomas (2003), Knaust (2004), Kulkarni and Borkar (2014), Kumpulainen et al (2006), Maples and Archer (1987), Maples and Suttner (1990), Martino (1989), Mikulas (1993), Minter et al (2007), Morrissey and Braddy (2004), Narbonne (1984), O'Sullivan et al (1986), Pearson (1992), Pickerill (1991), Pickerill (1992), Pickerill et al (1987), Pickerill et al (1984), Prescott et al (2014), Qi et al (2012), Savoy (1992), Smith (1993), Stephenson and Gould (1995), Tanoli and Pickerill (1989), Thomas and Smith (1998), Tunbridge (1984) and Weber and Braddy (2004). they are reported in Late Silurian-Early Devonian deposits from transitional continental-marine settings in the Ringerike Group of Norway, Tumblagooda Sandstone of Western Australia, and Mereenie Sandstone of the Northern Territory, Australia (Trewin and McNamara, 1994;Davies et al, 2006 Gouramanis and…”