Skip to content Skip to navigation

Article: Embryonic ammonoid shell features: intraspecific variation revisited

Publication: Palaeontology
Volume: 44
Part: 1
Publication Date: January 2001
Page(s): 53 64
Author(s): Isabelle Rouget and Pascal Neige
Addition Information

How to Cite

ROUGET, I., NEIGE, P. 2001. Embryonic ammonoid shell features: intraspecific variation revisited. Palaeontology44, 1, 53–64.

Online Version Hosted By

Wiley Online Library
Get Article: Wiley Online Library [Pay-to-View Access] |


Two samples of ammonoids belonging to the Oppeliidae, Sublunuloceras virguloidesHecticoceras (Brightii) canaliculatum, are analyzed to estimate the intraspecific variability of embryonic shell features. The study of embryonic shell characters reveals two main shapes of protoconch, flattened and round. Prosiphons may be straight or slightly curved. New parameters for area are added to the linear parameters commonly found in the literature. Prosiphon length and caecum area vary greatly whereas protoconch and ammonitella diameter vary only slightly, and the ammonitella angle is almost constant. The protoconch-to-ammonitella size ratio behaves differently in each species, suggesting different patterns of embryonic growth. We compare our results with published data and discuss their significance for species determination and ontogenetic interpretation. The main finding is that intraspecific embryonic variation is greater than was previously believed.
PalAss Go! URL: | Twitter: Share on Twitter | Facebook: Share on Facebook | Google+: Share on Google+