Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Functional significance of parabolae, interpreted on the basis of shell morphology, ultrastructure and chemical analyses of the Callovian ammonite Indosphinctes (Ammonoidea: Perisphinctidae), Central Russia
Swedish Museum of Natural History, Department of Paleobiology. (palaeozoology)
2012 (English)In: Revue de Paléobiologie, Genève, ISSN ISSN 0253-6730, Vol. 11, 89-101 p.Article in journal (Refereed) Published
Abstract [en]

The parabola-bearing shells of the Callovian ammonite Indosphinctes (Elatmites) submutatus Nikitin from Ryazan Region, Central Russia, are examined using morphological, ultrastructural and chemical approaches to clarify the functional significance of the parabola.The parabolae are missing in the embryonic shell that is comparatively large (about 1.5 mm in diameter) and has a prismatic shell wall, with the exception of the nacreous primary varix. There are no parabolae at the early post-hatching stage at which the shell wall consists of the outer prismatic, middle nacreous and inner prismatic layers. The parabolae are observed in small and medium-sized shells (about 15-30 mm in diameter) in which the bulk of the lateral and ventral portions of the shell wall are formed by the nacreous layer, and the outer prismatic layer seems to be missing. The thin dorsal wall lacks the nacreous layer, and the adjacent whorls are connected via a structureless layer showing a nano-granular ultrastructure. Beyond the contact of the whorls, the broken rolled ends of this layer are only preserved at the corners between the neighboring whorls. This perishable layer contains N (an indicator of organic ingredient preserved), C, O, Mg, Ca, Fe, Zn, and Sr. The same elements are detected in the structureless shell material from repaired injuries of the shell wall. There are about seven parabolae in a whorl. The parabolae are commonly exhibited on the exposed dorsal wall when the next whorl is broken. The parabolae are also observed on the outer shell surface not yet covered with the dorsal wall of the next whorl. The body chamber is about 330° in spiral length. The paired adorally ‘opened’ parabolic ‘notches’ are expressed either as small knobs on internal moulds, as nodes on the dorsal wall, or as a contour reinforced with minor relief on outer surface of the body chamber. A parabolic node represents a lens-like inclusion into the nacreous layer of the shell wall and is composed of flattened, loosely packed spherulites and nacreous micro-chips. Based on these observations it is suggested that (1) the shell of I. (E.) submutatus, excepting earlyontogenetic stages, was coated with an organic-rich layer, possibly secreted from the outside like the outer plate in the shell wall of extant Spirula; (2) the parabolae served as attachment structures related to the mantle attachment inside and outside the body chamber.

Place, publisher, year, edition, pages
Genève, 2012. Vol. 11, 89-101 p.
Keyword [en]
Ammonites, perisphinctids, shell wall ontogeny, parabolae, Jurassic, Central Russia
National Category
Natural Sciences
Research subject
Diversity of life
Identifiers
URN: urn:nbn:se:nrm:diva-1361OAI: oai:DiVA.org:nrm-1361DiVA: diva2:862525
Projects
shell morphology and ultrastructure as a key to cephalopod phylogeny
Available from: 2015-10-22 Created: 2015-10-22 Last updated: 2015-11-26Bibliographically approved

Open Access in DiVA

No full text

By organisation
Department of Paleobiology
Natural Sciences

Search outside of DiVA

GoogleGoogle Scholar

Total: 39 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf