ONTOGENY AND VARIABILITY IN RIBBING OF LATE VALANGINIAN LAMELLAPTYCHI (AMMONITINA)
Zdeněk VAŠÍČEK (1), Jaap KLEIN (2) & Nico M. M. JANSSEN (3)
1) Institute of Geonics, Academy of Sciences of the Czech Republic, Studentská 1768, CZ-70800 Ostrava-Poruba, Czech Republic; e-mail: zdenek.vasicek at ugn.cas.cz
2) Demmerik 12, NL-3645 EC Vinkeveen, the Netherlands; e-mail: jaap.klein at zonnet.nl
3) Waalstraat 156A, NL-3522 SV Utrecht, the Netherlands; e-mail: hibolithes at hotmail.com
