Trace fossil assemblages in Upper Silurian tuff beds: Evidence of biodiversity in the Old Red Sandstone of southwest Wales, UK

Siluro-Devonian trace fossils from the Mereenie Sandstone, Kings Canyon, Watarrka National Park, Amadeus Basin, Northern Territory, Australia

“…A few traces appear to be influenced by active water currents during or after their formation. The co-occurrence of Diplichnites, Beaconites, Taenidium and Skolithos-like traces appears to represent a typical ichnofossil association of mid-Palaeozoic paralic to fluvial successions (Bradshaw 1981, Trewin & McNamara 1994, Gouramanis et al 2003, Marriott et al 2009, although some similar assemblages may be found in strata as old as the Early Ordovician (Weber & Braddy 2003).…”

“…Beaconites antarcticus and Taenidium barretti are commonly associated in midPalaeozoic fluvial deposits globally (Bradshaw 1981, Allen & Williams 1981, O'Sullivan et al 1986, Marriott et al 2009, and both are represented in the Mereenie Sandstone. The identity of the B. antarcticus burrow maker is uncertain, but such traces have generally been attributed to small arthropods or, less commonly, to annelids and even holothurians (Bradshaw 1981, Weber & Braddy 2003.…”

Humans as the third evolutionary stage of biosphere engineering of rivers

“…This trace fossil record illustrates the Palaeozoic establishment of non-marine ecosystems and, in rivers particularly, the success of land plants as ecosystem engineers that created new biogeomorphic alluvial habitats for a range of plant and animal life (Davies and Gibling, 2013). The oldest unequivocal alluvial trace fossil assemblages are dominated by arthropod trackways and appear globally in the rock record in Silurian (circa 0.423 Ga) alluvium Hunter and Lomas, 2003;Trewin and McNamara, 1995), followed by fish traces and arthropod and other invertebrate burrows which appear and then diversify from the latest Silurian and Devonian (circa 0.419 Ga) onwards (Allen and Williams, 1981;Marriott et al, 2009;Minter et al, in press). The biogeomorphic effects of land plants and the burrowing of alluvial sediments by animals have largely persisted since their first occurrences in the geological record.…”

Carbon isotopic evidence for organic matter oxidation in soils of the Old Red Sandstone (Silurian to Devonian, South Wales, UK)

“…Contemporaneous volcanic tuffs were probably sources of calcium for the calcretes and are interbedded throughout the succession (e.g. Marriott et al 2009). The upper Přídolí Moor Cliffs Formation is a mudstone-dominated, heterolithic succession of moderately sinuous ephemeral river channel and floodplain deposits that were pedified to varying degrees as calcic palaeo-Vertisols, of which the C horizons are often defined by the presence of pedogenic calcrete (as further described below; Allen & Williams 1979;Marriott & Wright 1993.…”

“…All stages of calcite precipitation could have happened syndepositionally, associated with CO 2 degassing from the soil zone to the atmosphere. Samples of micritic oval pellets, 0.5 cm in diameter, probably of faecal origin (Allen & Williams 1981;Marriott et al 2009) and calcitized horizontal burrow fills (perhaps Beaconites barretti; see Marriott et al 2009), of up to 3 cm length and 0.5 cm width, were also taken.…”