Environmental significance of lungfish burrows (Gnathorhiza) within Lower Permian (Wolfcampian) paleosols of the US midcontinent
Abstract Burrows of the lungfish Gnathorhiza occur in the fine-grained strata of the Lower Permian (Wolfcampian) Blue Spring Shale Member, of the Matfield Formation near Manhattan, Kansas. Thousands of lungfish burrows occur in three beds of a compound paleosol profile, with the vast majority confined to a single bed several meters below the Florence Limestone Member of the Barneston Limestone (Chase Group). The burrows, a high percentage of which contain lungfish bones, occur in a 145 m long lens-shaped unit comprised of clayey siltstone that exhibits platy to subangular-blocky peds, and downward and laterally branching thin rhizoliths. The uppermost paleosol horizon in each level is gleyed, indicating that there was standing water for part of the year. The paleoecosystem represented by these units formed in a low-lying terrestrial coastal paleolandscape with subtle topography and imperfectly drained paleosols equivalent to present-day aquents. These paleosols are part of a pedogenic sequence recording an upward climatic trend from semi-arid to monsoonal.