. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum . & WILLIAM JAMES KENNEDY Geological Collections, Oxford University Museum of Natural Histoiy, Oxford E-mail uk (With 10 figures) [MS accepted February 2003] ABSTRACT Examination of more than one hundred specimens of the Coniacian heteromorph ammonitePseudoxybeloceras matsumotoi Collignon, 1965, from Madagascar and two from KwaZulu (Zululand)shows that coiling is in an open criocone and that, due to the shell structure, ornament variesconsiderably between internal moulds of
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum . & WILLIAM JAMES KENNEDY Geological Collections, Oxford University Museum of Natural Histoiy, Oxford E-mail uk (With 10 figures) [MS accepted February 2003] ABSTRACT Examination of more than one hundred specimens of the Coniacian heteromorph ammonitePseudoxybeloceras matsumotoi Collignon, 1965, from Madagascar and two from KwaZulu (Zululand)shows that coiling is in an open criocone and that, due to the shell structure, ornament variesconsiderably between internal moulds of the phragmocone and body chamber respectively, and inspecimens with shelly preservation. The specimens also exhibit some variation in whorl section andornamentation on both phragmocones and body chambers. CONTENTS PAGE Introduction 201 Material 201 Coiling 203 Shell structure and ornamentation 203 Intraspecific variation 207 Dimensions 209 Acknowledgements 215 References 215 Ann. S. Afr. Mus. 110 (5), 2003: 199-218, 10 figs. 200 ANNALS OF THE SOUTH AFRICAN MUSEUM *** .*. Figure 1 Pseudoxybeloceras matsumotoi Collignon, 1965. GD14000 from Gisement 462. The most complete specimen consisting of an inner phragmocone and an outer body chamber whorl, illustrating the apparent open, elliptical crioconic coiling of the adult shell, x 1. OBSER VA TIONS ON PSEUDOXYBELOCERAS MATSUMOTOI 201 INTRODUCTION In 1999 and 1993 respectively we had the opportunity to examine both the type andundescribed material in the General M. Collignon collection of Cretaceous fossils fromMadagascar, which is now permanently housed at the Centre des Sciences de la Terre,Universite de Bourgogne, in Dijon. Amongst these, we were able to examine more than ahundred specimens of the Coniacian heteromorph ammonite Pseudoxybelocerasmatsumotoi Collignon 1965 (1965: 12, pi. 419 (fig. 1731)). These, as well as twospecimens from the Coniacian of Kwazulu, allow us to comment on the ontogeny, shellstructure and resultant di
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