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Crustacean trace fossils provide invaluable information to paleobilogical, environmental and ecological interpretations in the Earth history. Here we report an unusually large (segments up to 58 mm across), three-dimensional burrow system from the Lower Devonian Pingyipu Formation, which was deposited in a nearshore setting on the northwestern Yangtze Platform, South China. The burrow system is dominated by horizontally-developed networks probably with vertical shafts connecting to the sediment-water interface. The burrow surfaces show no signs of lining but are characterized by scratches including ridges and bundles of ear-shaped striae, implying an assignation to Spongeliomorpha aff. S. chevronensis (Muñiz and Mayoral 2001). The overall morphological and taphonomic features suggest permanent, open burrows, produced in a substrate with considerable firmness. Further investigation indicates that the burrow system may have been constructed by a colony of large, unknown crustacean with thoracic appendages decorated with acute seta or denticulations. They generally served a combined purpose of dwelling and perhaps feeding on microbial growth accumulating on the tunnel margins. These burrows represent the earliest known three-dimensional burrow systems constructed by a crustacean that may be comparable to their modern analogues in both morphological and functional aspects. The unusually large size of the burrows may have been favored by a higher atmospheric oxygen level during the Early Devonian. • An unusually large burrow system from the Lower Devonian is illustrated. • It is the earliest known three-dimensional system constructed by crustaceans. • Morphological and functional features may be comparable to its modern analogues. • Occurrence of the burrows was favored by a higher atmospheric oxygen level. [ABSTRACT FROM AUTHOR]