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16 June 2014 The Soft-Tissue Attachment Scars in Late Jurassic Ammonites from Central Russia
Aleksandr A. Mironenko
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Abstract

Soft-tissue attachment scars of two genera and four species of Late Jurassic craspeditid ammonites from the Russian Platform are described. A previously suggested relationship between lateral attachment scars and ammonoid hyponome is confirmed, however, a new interpretation is proposed for dorsal attachment scars: they could have been areas not only for attachment of the dorsal (nuchal) retractors, but also of the cephalic retractors. The new type of the soft-tissue attachment—anterior lateral sinuses, located between the lateral attachment scars and the aperture of the ammonite body chamber is described. Enclosed elliptical or subtriangular areas in apertural parts of the anterior lateral sinuses were found for the first time. Their presence and location suggest that this structure could have been used for attaching the funnel-locking apparatus, similar to those of coleoids. A transformation of shape and position of lateral attachment scars through the evolution of the Late Jurassic craspeditid lineage starting from platycones (Kachpurites fulgens) to keeled oxycones (Garniericeras catenulatum) is recognized.

Copyright © 2015 A.A. Mironenko. This is an open-access article distributed under the terms of the Creative Commons Attribution License (for details please see http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Aleksandr A. Mironenko "The Soft-Tissue Attachment Scars in Late Jurassic Ammonites from Central Russia," Acta Palaeontologica Polonica 60(4), 981-1000, (16 June 2014). https://doi.org/10.4202/app.00041.2013
Received: 9 November 2013; Accepted: 1 May 2014; Published: 16 June 2014
KEYWORDS
Ammonoidea
attachment scars
Craspeditidae
Garniericeras
Jurassic
Kachpurites
Paleobiology
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