Acta Palaeontologica Polonica

Post-extinction survivor fauna from the lowermost Famennian of eastern North America

Jed Day and D. Jeffrey Over

Acta Palaeontologica Polonica 47 (2), 2002: 189-202

An earliest Famennian (Late Devonian) shell bed was discovered in the Hanover Shale Member of the Java Formation 1.4 meters above the Frasnian-Famennian (F-F) boundary in western New York. The invertebrate shelly fauna of the shell bed (Lower Palmatolepis triangularis conodont Zone), provides information on taxonomy of an outer shelf benthic association during the survival interval of recovery in the Appalachian foreland basin soon after the terminal Upper Kellwasser event marking the F-F mass extinction. Shelly invertebrates are extremely rare in the upper Hanover immediately above and below the shell bed. Abundance of brachiopod valves and remains of other groups in the shell bed reach 80-100 valves/100 cm2. Elongate valves of the linguloid brachiopod Barroisella cf. B. campbelli have preferred alignments roughly parallel to direction of down-slope flow in the deep-water foreland basin depositional setting. The brachiopod fauna is dominated by the representatives of Retichonetes, Barroisella, Cyrtospirifer, Tylothyris, and Praewaagenoconcha. Rare elements include species of Thiemella, Schizophoria, Ripidiorhynchus?, Chapinella?, an indeterminate rhynchonellid, Ambocoelia, and extremely rare Orbiculoidea. Forms including Cyrtospirifer hornellensis, Tylothyris mesacostalis, Praewaagenoconcha speciosa, and few others are late Frasnian carryovers. The range inception of Thiemella leonensis is just above the F-F boundary (Upper Kellwasser horizon) in the upper Hanover Shale shell bed in the western Appalachian foreland basin.

Key words: Brachiopoda, Conodonta, extinction, survivor fauna, Frasnian, Famennian, North America.

Jed Day [], Department of Geology and Geography, Illinois State University, Normal, Illinois 61790−4400, USA; D. Jeffrey Over [], Department of Geosciences, SUNY−Geneseo, Geneseo, New York 14454, USA.

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