Unusual accessory muscle scar patterns in two species of Palaeoneilo, a paleotaxodont bivalve from the Devonian of Bolivia

Abstract

New Devonian fossil material from Bolivia includes internal molds of two species of paleotaxodont bivalve, Palaeoneilo musculosa (Knod) and P. pondeana (Hartt and Rathbun), with numerous accessory muscle scars. The unusual pattern of these scars appears to have been derived from excessive splitting. These muscle scars are described and a tentative interpretation is made. An adaptative role cannot be determined with certainty and it appears that these patterns were short-lived novelties without later success.