SOFT-BODIED EDIACARAN MACROFOSSILS OR STRANGE SEDIMENTARY STRUCTURES? DECIPHERING THREE-DIMENSIONAL CORRUGATED TUBES FROM THE GREAT BASIN, CALIFORNIA

Within the latest Ediacaran Deep Spring Formation of southeastern California, a <5-meter interval of siliciclastic sediments deposited in an intertidal environment contains multiple bedding surfaces with enigmatic, three-dimensionally preserved corrugated tubes. Superficially, these resemble larger versions of annulated tubular soft-bodied macrofossils, such as Gaojiashania and Shaanxilithes, that are common in late Ediacaran biotic assemblages regionally and globally. Despite morphological similarities to casts and molds of body fossils preserved in correlative strata, we suggest these tubes are instead sedimentary structures that formed through differential compaction of rapidly deposited rippled sandstone and mudstone interbeds with widespread microbial mat layers. These distinctive sedimentary features may have formed as the result of a unique combination of environmental and ecological conditions in the latest Ediacaran Period. Differentiating macrofossils, microbial textures, and abiotic sedimentary features in Ediacaran strata is critical to identifying genuine evidence of early metazoans and understanding their taphonomic windows.