BRACHIOPODS OF THE SUPERFAMILY LINOPRODUCTOIDEA STEHLI, 1954: A NEW VIEW ON THEIR MORPHOGENESIS AND TAXONOMIC STRUCTURE

Abstract

In addition to the initial spine-distribution pattern, in which the posterior and anterior spines on the ventral valve surface are of approximately the same thickness, the Linoproductoidea evolved (very early in the Carboniferous) two other patterns, in which the thickest spines are confined (1) to the hinge margin and (2) to the trail. The latter pattern was sometimes unstable (reversible); however, the phyletic lineage in which this pattern occurs may be characterized by another character, an unusual pattern of ribs on the trail. These three patterns correspond to three new families, Monticuliferidae, Schrenkiellidae, and Linoproductidae, which have retained their old names but changed their meanings. There is one more family, Fluctuariidae, which is characterized by irregular concentric plications on the venter.