Taphonomy of tubular fossils (algae) from the deposits of the Late Ediacaria of Ukraine

• The collection of Ediacaran algal flora is stored in the Institute of Geological Sciences of the National Academy of Sciences of Ukraine. These fossils were collected by Andrii Martyshyn in southwestern Ukraine. Within the framework of the priority topic “Integration of large-scale geological data to solve fundamental and applied problems of Ukraine”, which is being carried out at the Institute, the collection was revised. New fossil specimens of giant tubularstructures were also added, which we recently discovered in sediments (argillites, siltstones, sandstones) of the Mohyliv-Podilska series of the Ediacaran (Dniester river valley, southwestern Ukraine). The material is represented by three taphonomic variants of these remains: three-dimensionally preserved rods, phytoleimes and rods with charred shell fragments. We have collected a large number of fossils of soft-bodied organisms, trace fossils, macroalgae and problematic remains. Analysis of our findings suggests that some known and new fossils are likely to be the remains of algae. This interpretation is based on findings that demonstrate the different taphonomic states of preservation. The material of the new species of the previously described genus Harlaniella Sokolov in argillitic strata of the Kanylivka Group was described as traces of movement of worm-like creatures. These fossils look like straight or curved rods with oblique hatching on the lower surface of the rock. There are no trace fossils with similar morphology in the fossil record of the Phanerozoic. Our new material shows that the fossils were organic tubes with a smooth surface and an obliquely transverse sculpture on the inner surface of the wall. We found specimens with examples of the transition from smooth tubes into hatched rods and carbonaceous compression fossils (phytoleims). Similar phytoleims are widespread in this stratum and are described as remnants of probable brown algae Vendotaenia Gnilovskaja. New finds demonstrate a morphology different from the holotype: numerous branching segments and elasticity of deformed tubes. We did not detect holdfasts attaching bodies to the substrate, indicating a probable planktonic habit for these putative algae.

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NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Annan geovetenskap och miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Other Earth and Related Environmental Sciences (hsv//eng)

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