Morphology and Paleoenviromental Distribution of Paleozoic Spirophyton and Zoophycus; Implications for the Zoophycus Ichnofacies

Spirophyton producers inhabiting ephemeral ponds on estuarine floodplains marginal to the (Devonian) Catskill sea covering present-day southern New York were subjected to salinity fluctuations and desiccation, whereas Zoophycos producers living farther offshore were buried by storm deposits. Producers of Zoophycos living in interdistributary bays on Pennsylvanian lower delta plains (Tennessee) contended with fluctuations in salinity and oxygen conditions and variations in sediment grain size and in rate of sedimentation. In each case the producer was an r-selected opportunistic species, as shown by the distribution of the Spirophyton or Zoophycos and the paucity of co-occurring trace fossils. Morphologic analysis indicates that the Paleozoic producers of these Zoophycos and Spirophyton: (1) transported sediment downward from overlying layers or the sediment surface, and (2) were capable of a variety of behavioral patterns, only some of which resulted in complex 3-dimensional structures.