A Large Trace Fossil in Nodular Limestones (Lower Devonian, Czech Republic): Sedimentological Consequences, Ethology and Taphonomy

Abstract

Large star-like trace fossil was found on the upper bedding plane of nodular limestone of the Praha Formation (Pragian, Devonian) at Praha, Czech Republic. It was tentatively placed to the ichnogenus Capodistria. It is interpreted as a feeding trace that originated on the seafloor surface. The structure consists of 10-11 radial rays and its longer axis is 60 cm. The rays are preserved as concave epireliefs, up to 10 mm deep and 25 mm wide. The trace fossil partly intersects nodules that cover surfaces of most bedding planes of the Praha Formation, demonstrating that the nodules formed during the earliest stages of diagenesis.

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“…Intersections also occur the other way around, with nodules partly intersecting the trace fossils. This is unambiguous evidence for the simultaneous occurrence of the biogenic activity and the formation of the undulatory surfaces on the sea floor (Mikuláš and Hladil, 2015). The fact that these syn-or early post-depositional features are preserved makes differential diagenesis clearly not a prominent player in this setting.…”

“…As Matys Grygar writes: This "could definitely show whether the nature (grain size, provenance, mineralogy) of the clastic components changed periodically, as would be expected for a climatic signal." Furthermore, the Praha Formation includes carbonate beds with nodular structures, or knobbly bedding surfaces (sensu Mikuláš and Hladil, 2015; see also Fig. 1).…”

Unravelling Phanerozoic evolution of radial to rosette trace fossils

“…working below the sand (Książkiewicz ). This ichnogenus seems to be restricted to deep‐marine slope to basin plain environments, having been recorded from the Lower Devonian (Pragian) to the Miocene (Vyalov ; Książkiewicz ; Brustur & Ionesi ; Uchman , , ; Demírcan & Toker ; Mikuláš & Hladil ). Some deep‐marine recent traces (Bell et al .…”

“…2D and 3D schematic reconstructions of radial rosette trace fossils. Arenituba based on Chamberlain (); Asterichnites based on Brown & Vokes (); Asterichnus based on Chamberlain (); Bifasciculus based on Volk (); Capodistria based on Mikuláš & Hladil (); and Cladichnus based on Wetzel & Uchman ().…”

“…This is a structure consisting of a few narrow radial tunnels and a central knob or knobs (Fig. E; Vyalov ; Mikuláš & Hladil ). This is a shallow‐tier trace fossil that is preserved as positive hyporelief (Fig.…”