Evidence for the presence of a heart in Paleozoic ostracodes inconclusive

The presence of a heart in some Paleozoic ostracodes has been inferred by analogy with some living myodocopids that have this organ, and an ordinal classification of the leperditiids has been proposed because of this inference. A review of the present knowledge of the internal shell structure of living myodocopids indicates that there is no basis for interpreting certain markings preserved on fossil molds and steinkerns as indicating the presence of a heart.