Furrows and firmgrounds: evidence for predation and implications for Palaeozoic substrate evolution in Rusophycus burrows from the Silurian of New York

Authors

  • LIDYA G. TARHAN,

  • SÖREN JENSEN,

  • MARY L. DROSER


Lidya G. Tarhan [lidya.tarhan@email.ucr.edu], Department of Earth Sciences, University of California, Riverside, Riverside, CA 92521, USA; Sören Jensen [soren@unex.es], Área de Paleontología, Facultad de Ciencias, Universidad de Extremadura, Avenida de Elvas s/n, E-06006 Badajoz, Spain; Mary L. Droser [mary.droser@ucr.edu], Department of Earth Sciences, University of California, Riverside, Riverside, CA 92521, USA; manuscript received on 14/01/2011; manuscript accepted on 24/05/2011.

Abstract

Tarhan, L.G., Jensen, S. & Droser, M.L. 2011: Furrows and firmgrounds: evidence for predation and implications for Palaeozoic substrate evolution in Rusophycus burrows from the Silurian of New York. Lethaia, Vol. 45, pp. 329–341.

The Silurian Herkimer Formation of east-central New York contains abundant, exceptionally preserved composite Rusophycus-Teichichnus burrows. We suggest that the most likely interpretation of these composite trace fossils is as structures formed by trilobites entering the sediment in search of prey. Parallel alignment of the paired traces, asymmetrical configuration of the Teichichnus along the longitudinal axis of the associated Rusophycus, depth correlation and deformation of the Teichichnus all suggest that this relationship was predatory. In addition, sectioned material indicates that these Rusophycus may have been open at the sediment-water interface, while the crisp preservation of both Rusophycus and Teichichnus, along with the preservation of such delicate morphological details as scratch marks, suggests that the sediment must have been relatively firm at the time the traces were formed. The formation and preservation of Rusophycus in cohesive sediments located very close to the sediment-water interface hold important implications for the manner in which we consider Palaeozoic substrates and their temporal and spatial evolution. Moreover, these findings demonstrate that the morphology and taphonomy of ichnological associations may, in the context of sedimentological relationships, prove a powerful proxy for tracking substrate conditions through both space and time. □firmgrounds, New York, predation, Rusophycus, substrate, taphonomy.

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