Abstract

The recent discovery of abundant trace fossils in the Lower Devonian Muth Formation (Pin Valley, Spiti, northern India) contributes to our understanding of the diversity and distribution of Early Devonian arthropod activities in a marginal marine environment. The ichnoassemblage consists of abundant Palmichnium antarcticum and Diplichnites gouldi with rarer Diplopodichnus biformis, Taenidium barretti, Didymaulichnus cf. lyelli, Didymaulyponomos cf. rowei, Selenichnites isp., and vertical burrows of unclear affinity. The abundance of trackways enables the documentation of size- and gait-variations among producers of single trackway ichnotaxa. The paleoenvironment of the Muth Formation is interpreted as a barrier island system. Four different facies associations are recognized; arthropod trackways occur only in beach to coastal dune environments (facies association 2). Most of the Palmichnium and Diplichnites trackways are interpreted as subaerial. The abundance and frequently sub-parallel orientation of the Palmichnium antarcticum trackways, predominantly perpendicular to the paleocoastline, suggest that stylonurid eurypterids, which are interpreted as their producer, were migrating across the shoreline and climbing up slip faces of barrier island dunes. The similarity of this ichnofauna to others in marginal marine environments of similar age in Antarctica and Australia allows the identification of a recurrent Lower Devonian ichnocoenosis around the margins of eastern Gondwana.

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