THE NEOICHNOLOGY OF BURROWING ARTHROPODS FROM EOLIAN ENVIRONMENTS

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Abstract In eolianites, body fossils are rare, leading to the reliance on ichnofossils for the interpretation of ancient eolian ecosystems. While many eolian ichnofossils are relatively simple to interpret, there are still those that are poorly understood. Among potential tracemakers, arthropods are most likely as they are common components of modern eolian ecosystems. Previous neoichnological experiments with continental animals have improved our understanding of the connections between behavior, substrate conditions, and three-dimensional burrows. However, most eolian ichnofossils are produced in loose substrates and observed in outcrop as two-dimensional expressions of three-dimensional structures and are, therefore, not conducive to such an experimental approach. This study examined the burrowing techniques, behaviors, and two-dimensional biogenic structures produced by five arthropod species, Smeringurus mesaensis, Hogna lenta, Eleodes armata, Orthoporus ornatus, and Ammopelmatus cf. fuscus, in loose sandy sediment of varying compositions and moisture levels. Resulting biogenic structure morphology, depth, and density were observed in two dimensions and compared to evaluate the relative effects of substrate conditions and tracemaker. The biogenic structures were also compared to ichnofossils from Mesozoic eolianites from around the world. Several key controls on trace morphology were identified including variations in substrate conditions. This study has helped to identify new potential behaviors and tracemakers in eolianite ichnofabrics. The continual refinement of interpretation of ichnofossils will aid in the understanding of paleoenvironmental conditions and the paleoecology of ancient eolian settings.

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