Supplementary Material

Appendix A. Video of the virtual transverse serial sections of specimen MNHN.F.A59944 of Cyclothyris difformis. (Patricia Wils, UMS 2700).

Appendix B. Video of the virtual longitudinal serial sections of the same specimen MNHN.F.A59944 of Cyclothyris difformis. (Patricia Wils, UMS 2700).

Appendix C. Virtual transverse serial sections of specimen MNHN.F.A59944 of Cyclothyris difformis. The numbered views correspond to a selection of virtual sections among the set of images.

Appendix D. Video of the virtual transverse serial sections of paratype MNHN.F.A26502 of Beaussetithyris asymmetrica from La Cadière. (Patricia Wils, UMS 2700).

Appendix E. SEM views of selected transverse sections of Senonian asymmetrical rhynchonellid shells. A,B. Beaussetithyris asymmetrica nov. sp. from Les Martigues: details of the articulation in section (dental plates (d. pl.), hinge plates (h.pl.), teeth (t) and crus (cr) in (A), the arrowhead indicates the location of the close-up view of the crus (B). C,D. Beaussetithyris asymmetrica nov. sp. from Le Beausset: details of the articulation in a section, note the dental sockets (d.s), and close-up view in the right side (D) shown by the arrowhead. E–G. Contortithyris thermae nov. sp. from Sougraigne, details of the shell articulation in a section; close-up view of the septum (s) in a partly recrystallized shell (G).

© D. Gaspard and S. Charbonnier, Published by EDP Sciences 2020