The bearing of the new Late Cambrian monoplacophoran genus Knightoconus upon the origin of the Cephalopoda

Lethaia
Compiled by: Ellis L. YochelsonRousseau H. Flower, and Gerald F. Webers

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Abstract

Knightoconus, a new genus of the Hypseloconidae (Mollusca: Monoplacophora) from rocks of early Franconian age in Antarctica, is multiseptate. The multiple septa are a criticàl feature to be expected in a form ancestral to cephalopods. Fossil cephalopods, however, invariably have a siphuncle as well as septa; some gastropods, some hyolithids, and some monoplacophorans also have septa but lack a siphuncle. Therefore, only the siphuncle can be considered a unique and particularly significant feature of the cephalopod shell. Hypothetical reconstructions of molluscan anatomy support the notion that cephalopods may have been derived directly from a hypseloconid having a high, slightly curved, multiseptate, bilaterally symmetrical shell, by the subsequent development of a siphuncle.

Publication type Article
Publication Subtype Journal Article
Title The bearing of the new Late Cambrian monoplacophoran genus Knightoconus upon the origin of the Cephalopoda
Series title Lethaia
DOI 10.1111/j.1502-3931.1973.tb01199.x
Volume 6
Issue 3
Year Published 1973
Language English
Publisher Geological Society of America
Description 35 p.
First page 275
Last page 309
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