Ammonites as Cartesian divers

Many constructional and taphonomic incongruencies dissolve if ammonites are modeled as active Cartesian divers, whose last septum remained a rubber-like, uncalcified membrane until the next chamber cycle began. If the prochoanitic invagination of the septal mantle served as a gas gland able to produ...

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Bibliographic Details
Published in:Palaios 1995-12, Vol.10 (6), p.493-506
Main Authors: Seilacher, A, Labarbera, Michael
Format: Article
Language:English
Subjects:
Ammonoidea
biologic evolution
Bubbles
Buoyancy
Cartesianism
Cephalopoda
Cephalopods
flotation
functional morphology
Geology
Invertebrata
invertebrate
modern
Mollusca
morphology
Muscles
Nautilus
Paleontology
septa
Septum
taphonomy
Tenth Anniversary Theme Issue
Tetrabranchiata
Water pressure
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Summary:Many constructional and taphonomic incongruencies dissolve if ammonites are modeled as active Cartesian divers, whose last septum remained a rubber-like, uncalcified membrane until the next chamber cycle began. If the prochoanitic invagination of the septal mantle served as a gas gland able to produce gas at or above ambient pressure, the chamber behind could be operated like a swim bladder by sutural muscles spanning across the septal mantle. Other septal functions probably served as evolutionary stepping stones on the way to this unique design.
ISSN:0883-1351
1938-5323
DOI:10.2307/3515089