Bacterial trace fossils in eocene kaolin of the huber formation of Georgia;phylloderma microsphaeroides, n. ichnogen., n. ichnosp.

An Eocene kaolin deposit in Georgia contains microspheres of tangentially oriented kaolinite enclosing authigenic cristobalite/tridymite overgrown with kaolinite. These structures resemble cutans of clay minerals that surround polysaccharide‐covered bacteria in recent soils and sediments. Bacteria actively synthesize anionic mucopolysaccharides as adhesives for attachment to surfaces. Empty cutans are common; these polymer‐bound clay mineral microspheres persist following cell death and lysis. Even though the void space thus created and associated organic material influence subsequent diagenetic changes, sedimentary microfabrics attributable to bacterial activity are preserved.