Trace fossils and palaeoenvironments of the Middle Devonian Caherbla Group, Dingle Peninsula, southwest Ireland

Abstract

Trace fossils from the Middle Devonian Caherbla Group of the Dingle Peninsula, southwest Ireland, record a diverse arthropod fauna inhabiting a hot-arid intracontinental rift setting. Aeolian dunefield and coeval fluvial interdune deposits interfinger spatially and temporally with alluvial fan sedimentary rocks. Three distinct trace fossil assemblages are recognized. The Taenidium-Scoyenia ichnocoenosis occurs in alluvial fan and fluvial channel deposits, and includes the large backfilled burrow Taenidium, interpreted as eoarthropleurid aestivation chambers. The Rusophycus-Protichnites ichnocoenosis, composed of arthropod trackways and surface pits, occurs in an interdune ponded area that was susceptible to ephemeral fluvial flow, with Rusophycus showing preferred orientation into the oncoming palaeocurrent. Both the TaenidiumScoyenia and Rusophycus-Protichnites ichnocoenoses are assignable to the globally recurring continental Scoyenia ichnofacies. They are clearly substrate-controlled and moisture-related due to the ephemeral nature of the fluvial system. The Palmichnium-Entradichnus ichnocoenosis occurs in aeolian dune deposits, and includes Palmichnium, attributed to large stylonurid eurypterids, and Diplichnites, attributed to eoarthropleurids. These trackways represent the activities of dune pioneers that left their fluvial habitat to forage for detritus. Interface burrows (Entradichnus, Palaeophycus) were also constructed by arthropods moving just under the sand surface and vertical burrows (Cylindricum, Pustulichnus) were made by arthropods digging downward. Trace preservation in the aeolian environment was probably enhanced by heavy nocturnal dew-fall or light rain. The Palmichnium-Entradichnus ichnocoenosis is assigned to the globally recurring aeolian OctopodichnusEntradichnus ichnofacies. This aeolian facies, and associated ichnofauna described herein, represents the oldest development of a unique erg system in the Old Red Sandstone (Devonian) of the southern British Isles, and one of the oldest and most diverse aeolian ichnofaunas to be reported worldwide.

Insights on the Behavior of Late Paleozoic Aquatic Crustaceans (Pygocephalomorpha?): Compound Trace Fossils from Western Argentina

“…The series overlap is variable between zero and 70% in both groups. The first group, typified by 6-11 tracks per series, includes the specimens described by Bradshaw (1981), Form B of Trewin and McNamara (1995), Form B of Draganits et al (2001), Type A of Smith et al (2003), Types A and B of Minter et al (2007b), Type A of Morrissey and Braddy (2004), and the specimens described by Retallack (2009) and Morrissey et al (2011). A similar track series is also found in Group A of Diplichnites isp.…”

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

“…7). Outside of the Stonehaven Group, the Old Red Sandstone of Anglo-Welsh Basin contains the oldest recorded example of fully terrestrial meniscate burrows in the global rock record (Morrissey et al, 2012a(Morrissey et al, , 2012b, in rocks of Pridoli age (Allen and Williams, 1981;Barclay et al, 2015). 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 in the global rock record, Arenicolites is reported from the Cambrian until the present day (Virtasalo et al, 2011), but absent in non-marine strata until the Pridoli (Morrissey et al, 2012a(Morrissey et al, , 2012b. The tracemaker is typically interpreted as being a vermiform organism (Häntzschel, 1975).…”

Deep-sea trace fossil and benthic foraminiferal assemblages across glacial Terminations 1, 2 and 4 at the “Shackleton Site” (IODP Expedition 339, Site U1385)

“…Open tube produced by carnivorous or omnivorous invertebrates, mainly polychaetes or arthropods. Pemberton and Frey (1982), Keighley and Pickerill (1995), Morrissey et al (2012) Planolites Medium size (5-7 mm in diameter), circular to subcircular form, unlined. Filling different from host sediment.…”