8 Fossils of Ohio: A Century after Newberry

Thursday, 20 April 2006
8:00 AM - 12:00 PM

EPIBIONTS ON THE BRACHIOPODS FROM THE DEVONIAN DUNDEE FORMATION OF OHIO

Paper number: 8-11
Program: THEME SESSIONS
Time: 11:20 AM – 11:40 AM

Authors

Abstract

The paleontology of the Middle Devonian Dundee Formation has not been well-studied. Some sedimentological and stratigraphic information is available for this unit, but the fossils from localities such as the Whitehouse Quarry, Lucas County, northwest Ohio, have not been rigorously collected and examined. In particular, the paleoecology of this fossiliferous marine unit should be better constrained. Epibionts are those invertebrates that attach permanently to the hard surface of the substrate. Determining the interrelationships among the brachiopod hosts and different epibionts will provide evidence for predation, parasitism, and other ecological interactions that occurred within this paleocommunity. In addition, comparison of the rate of encrustation of the carbonate Dundee Formation and the overlying siliciclastic Silica Shale Formation will shed light on the importance of host substrates in these two different environments.

Over one hundred brachiopod specimens were collected from a fossiliferous horizon of the Dundee Formation exposed at Whitehouse Quarry, and identified to the genus level. Shells were examined under the stereomicroscope for evidence of epibionts, and preferred host taxa were determined. Epibionts are extremely rare on these shells, although bryozoans, boreholes, and indeterminate grooves are present. Prior work has shown that the same brachiopod genera found in the Silica Shale Formation are often heavily encrusted. While one might expect encrustation on hardgrounds within this carbonate unit, field work has determined that much of the Dundee Formation was extensively bioturbated, implying a soft substrate. It may be that bioturbation mixed shells down into the substrate before epibionts could attach. This study will assist future workers to compare encrustation patterns on brachiopod hosts in carbonate and siliciclastic environments.