Comparing size of morphospace occupation among extant and cretaceous fossil freshwater mussels using Elliptical Fourier Analysis

Abstract

11Background. Freshwater mussels of superfamily Unionoidea are a diverse group 12 with an evolutionary history of at least 360 million years. Many fossil and modern 13 species exhibit a generally unsculptured, roughly elliptical shell outline. Such mor-14 phology results in difficulties when attempting to identify or classify fossil material, as 15 only hard parts are preserved. 16Several latest-Cretaceous fossil localities over a small geographic area in south-17 western North Dakota contain poorly preserved edentulous freshwater mussels that 18 effectively lack all but shell outlines. This paper discusses methods that were used to 19 attempt to determine how many fossil taxa were present in one of these assemblages.