Integration of tetrapod-track taphonomic modes and taphonomic pathways with the Lake-basin type model

Abstract

Lake systems contain outstanding sensitive integrated stratal records of environmental fluctuations that have been summarized in the lake-basin type (LBT) model. This model classified the stratigraphic record of ancient lake systems according to rates of potential accommodation relative to sediment+water supply. The LBT model convolved all modes and paths of water supply with amounts and types of sediment supply into a single basin-fill term (sediment+water) to provide widespread applicability.More recently, the model was enhanced and expanded. The elements of sediment+water supply were explicitly deconvolved (into through-flow, recharge, and discharge groundwater modes), the influence of the volume of sediment relative to water on lake hydrodynamics and ecosystems distinguished, and other parameters, such as invertebrate ichnofacies occurrence and distribution and groundwater hydrology, were integrated.Our detailed studies of vertebrate tetrapod tracks, their taphonomic modes, and ichnologic taphonomic pathways demonstrate their utility as sensitive indicators of environmental conditions of the track-bearing beds during imprinting and depositional processes in lacustrine systems. Three main tetrapod-track taphonomic-modes (TTTM) are defined based on the fidelity of anatomical features preservation: High-, Moderate-, and Low-fidelity. These modes strongly depend on the rheological condition of the sediment influenced by grain size distribution, mineralogy, stratal stacking at the bed scale, and moisture content?all of which are closely related to LBT, especially through the sediment+water supply factors.We propose integrating TTTM, ichnologic taphonomic pathways, and the spatial and stratigraphic distributions of vertebrate tracks with the LBT model to provide additional detailed insights into environmental and sedimentological conditions at the time of track imprinting. The wide array of Triassic Argentine paleolake records provide an excellent opportunity to characterize tetrapod footprint preservation and ichnofaunal taphonomic pathways in underfilled, balanced-filled, and overfilled lake-basins and to test this expansion of the LBT mod