Dermal element that arises via intramembranous ossification and are developmentally distinct from true ribs that articulate with the vertebral column.
Comment:
[taxon-note] "These bones may have been derived from the ventral scales found in animals like rhipidistians, labyrinthodonts, and Acanthostega, and may be related to ventral elements of turtle plastrons" xsd:string {source="WP"}