Late Mississippian vertebrate palaeoecology and taphonomy, Buffalo Wallow Formation, western Kentucky, USA

Abstract

Aquatic vertebrates are reported from several facies of the Late Mississippian (Chesterian/Elviran/Serpukhovian) Buffalo Wallow Formation in western Kentucky, USA. Rhizodont bones and the partially articulated skeleton of a large anthracosaur (proterogyrinid) were found in rocks interpreted as a fluvial‐estuarine palaeochannel. Smaller, disarticulated tetrapod remains (anthracosaurs, whatcheeriids) were found in a weathered siltstone in an apparent channel margin‐sand flat facies. A putative oxbow‐abandoned channel facies contains skeletal elements of rhizodonts (cf. Rhizodus), colosteiids, Gyracanthus, Ageleodus, Cynopodius, xenacanthoids and palaeonisiciforms. Near the top of the channel fill, lungfish (cf. Tranodis) are found in carbonate‐rich nodules, which appear to be aestivation burrows. A presumed lacustrine facies contained a near‐complete colosteid. Thinning section, palaeosols, pedogenically‐altered carbonates and missing strata suggest tectonic and climatic overprints upon these depositional sequences. Multiple, incised channels in a low‐accommodation setting are interpreted to have provided local faunal traps for aquatic vertebrates. Late Mississippian palaeoclimate changes may have caused water table fluctuations, which might have aided in trapping and preserving aquatic vertebrates.

Early Mississippian sandy siltstones preserve rare vertebrate fossils in seasonal flooding episodes

“…The coal‐bearing siltstone successions of the Pennsylvanian Joggins Formation of Nova Scotia may also include sandy siltstones in the green‐grey siltstones of the poorly‐drained floodplain facies assemblage (Davies & Gibling, ). The Lower Pennsylvanian Buffalo Wallow Formation of Hancock County, Kentucky, contains a comparable vertebrate fauna of tetrapods, dipnoans, rhizodonts, actinopterygians, acanthodians and chondrichthyans within abandoned channel and oxbow facies (Garcia et al ., ; Greb et al ., ). Although sandy siltstones are not identified, tetrapod remains are also found within rooted siltstone palaeosol horizons, which could be analogous to the original environment of the Ballagan Formation tetrapods.…”