Normannites

Normannites is a strongly ribbed evolute Middle Jurassic[1] genus of ammonite included in the stephanoceratoid family Stephanoceratidae.

Normannites
Temporal range: Bajocian[1]
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Fossil specimen of Normannites braikenridgei from Mid Jurassic - Germany
Fossil
Scientific classification
Kingdom:
Animalia
Phylum:
Mollusca
Class:
Cephalopoda
Subclass:
Ammonoidea
Order:
Ammonitida
Family:
Stephanoceratidae
Genus:
Normannites

Munier-Chalmas 1892

Normanites was previously included in the Otoitidae by Arkell et al. 1957. More recent classifications show it to belong to the family Stephanoceratidae, along with genera like Stephanoceras and Stemmatoceras.

Description

Normannites has shells reaching a diameter of 52–55 millimetres (2.0–2.2 in). These shells have large lappets, curved plate-like structures that project forward on either side of the aperture. Primary ribs on the inner side of each whorl are large and close spaced, bifurcate about mid flank before continuing over the venter. Secondary ribs, when present, appear about mid flank between primary pairs.

Stephanoceras differs in its tendency to develop tubercles at the point of furcation in the primary ribs. Primary ribs, low on the whorls, in Stemmatoceras tend to be narrower and sharper.

Selected genera

Distribution

Jurassic of Saudi Arabia [2]

References
  1. Sepkoski, Jack (2002). "Sepkoski's Online Genus Database". Retrieved 2014-05-28.
  2. "Paleobiology Database - Normannites". Retrieved 2014-05-28.
  • Arkell, W.J.; Kummel, B.; Wright, C.W. (1957). Mesozoic Ammonoidea. Treatise on Invertebrate Paleontology, Part L, Mollusca 4. Lawrence, Kansas: Geological Society of America and University of Kansas Press.
  • Normanites sp

, jsdammonites.fr


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