Biofilm assists recognition of avian trackways in Late Pleistocene coastal aeolianites, South Africa

Helm, Charles W.
Anderson, Robert J.
Buckley, Lisa G.
Cawthra, Hayley C.
de Vynck, Jan C.
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Evolutionary Studies Institute
Fourteen fossil avian tracksites have been identified in Late Pleistocene aeolianite deposits on the Cape south coast of SouthAfrica. One of these sites is unusual because of the preferential adherence of organic material (biofilm) to the natural cast tracks. This has enabled the recognition and identification of two ~6 m long, approximately parallel trackways that would otherwise not have been noticed. The trackways are visible from a distance of over 100 metres and contain 20 and 14 individual tracks, respectively. Up to 50 avian tracks are evident at this site. As the biofilm layer continues to thicken, the trackways become increasingly visible. Avian trackways of this length are globally rare.We propose that the biofilm adheres to sections with higher relief on a sedimentary surface, and that an understanding of this mode of preservation can be useful to more easily identify trackways in areas of comparable geological setting.
biofilm, avian trackways, aeolianites, Pleistocene