PRELIMINARY LOOK AT BIVALVE RANGES THROUGH THE KELLWASSER EVENTS OF THE UPPER DEVONIAN IN THE APPALACHIAN BASIN

The rock record of the Appalachian basin preserves several Devonian mass extinctions, including the Lower and Upper Kellwasser events. These beds provide us with the opportunity to examine the effects of extinction events on marine communities and their constituents. Bivalves are an often-overlooked element of Paleozoic marine communities. Although abundant in the Devonian, they have been understudied for decades. This study aims to provide a first look at the ranges of bivalve taxa through the Kellwasser events in the Upper Devonian.

Fieldwork covered 5 localities across New York and Pennsylvania and was supplemented by pre-existing collections providing material from 4 additional localities. We collected 179 bivalve specimens across both Kellwasser events. All material was whitened with ammonium chloride to aid with identification and the specimens’ stratigraphic positions were recorded. The taxonomic disarray of the Upper Devonian bivalves from northeastern US has complicated this work and prevented species-level identification in some cases.

Two-thirds of the material was identified to species or genus level. Out of the collected samples, pteroids are the most abundant taxa. The genus Leptodesma is represented with 46 occurrences and survives both Kellwasser events while Cornellites chemungensis does not occur after the first Kellwasser horizon. Mytiloids increase in abundance after the Lower Kellwasser. The genus Spathella is the only representative of this group to occur before the Lower Kellwasser that became more abundant in the Canaseraga Formation (i.e., after the Lower Kellwasser), when it is joined by other mytiloid taxa such as Mytilarca and Glossites, which all survive into the Famennian. Of the family Nuculidea, Palaeoneilo is the only taxon surviving both Kellwasser events. We were able to detect other nuculids before and after the first Kellwasser horizon, but not after the second event.

These preliminary observations are a first general attempt to improve our understanding of the effects of biological turnover events on bivalve communities in the Upper Devonian. More samples and a revised taxonomy will also allow more insight into the extinction sensitivity of this group.