Novel Neoichnology of Elephants: Nonlocomotive Interactions with Sediment, Locomotion Traces in Partially Snow-Covered Sediment, and Implications for Proboscidean Paleoichnology

Abstract

We observed trace-making behaviors of one female African elephant (Loxodonta africana) and one female Asian elephant (Elephas maximus) in a zoo setting. Our objective was to document uncommonly studied traces, that is, traces other than dung and footprints in sediments, so that paleoichnological researchers may benefit from a broader search pattern when investigating trace fossils with potential proboscidean affinities. We observed six distinct traces: trunk-grasping traces, small pits from active and passive dispersal of water and sediment, urination traces, resting traces, wallowing traces, and dissected tracks created in partially snow-covered sediment. Of these traces, none attributable to proboscideans have been reported in the fossil record. The resting traces we observed, however, were created in dry sand and would likely not be preserved in the fossil record because of a high potential for disturbance before burial. Similarly, the trunk traces we observed in dry sand would likely have low preservation potential. Pits from thrown and blown sediment and water, wallowing traces, and snow-influenced tracks should have a higher probability of survival into the fossil record. Tracks representative of partially snow-covered ground are recognizable by sediment pedestals within undertracks. In such tracks, which we refer to as hanging tracks, the top surface of the pedestal is all that remains of the true track. The undertrack surrounding the pedestal(s) was created from the elephant’s foot pressing snow into the underlying sediment. The snow later melted away. Pleistocene proboscideans likely encountered partially snow-covered ground, so hanging tracks may be preserved in the rock record. Recognition of these tracks would be extremely informative about paleoclimate, but further research is needed to determine if they can be easily distinguished from tracks created exclusively in sediment.