Lacustrine Environments - Trace Fossils as Indicators of Sedimentary Environments - page 395

FIGURE 10 Trace fossils in underfilled lake-type basins. (A-D) Examples from the Wilkins Peak
Member of the Eocene Green River Formation, Wyoming, USA. (A) High-density, low-diversity
expression of the Mermia Ichnofacies in low-energy littoral-zone deposits. (B) Medium-sized
vertical burrows of the Skolithos Ichnofacies in wave-influenced littoral to eulittoral zone deposits.
(C) Horizontal, meniscate-backfilled burrows of the Scoyenia Ichnofacies in low-energy, subaeri-
ally exposed mud flats of the eulittoral zone. (D) Shorebird footprints of the Scoyenia Ichnofacies in
lake marginal facies of the Wilkins Peak Member, Eocene Green River Formation. (E) and (F)
Examples from the Permian of the Paganzo Basin, Argentina. (E) “Tracked omission surface” show-
ing high-density arthropod trackways of the Scoyenia Ichnofacies. (F) Close-up of a “tracked omis-
sion surface”, illustrating the Scoyenia Ichnofacies.
are low. The Scoyenia Ichnofacies is present in eulittoral to supralittoral zones,
where lake-level fluctuations cause the frequent flooding and subaerial expo-
sure of both, high-energy sandy beach deposits and low-energy fine-grained
mud flats ( Figs. 9 and 10 ). Insect trackways, burrows and vertebrate footprints
are typical components ( Fig. 10 ; e.g., Knaust and Hauschke, 2005; Lucas et al.,
2011; Minter et al., 2007; Zhang et al., 1998 ). Lake-level rise may lead to
increases in species diversity around lake margins in response to a decrease