Cretaceous spirulids
Dirk FuchsIntroduction
While Cenozoic representatives of the Spirulida are well-known since the 19th century, Cretaceous ancestors of Spirula are first evident since Jeletzky (1966). Owing to a Spirula-like caecum that enters the lumen of the protoconch of a Late Cretaceous orthoconic phragmocone with conspicuously long chambers and without a belemnite-like rostrum, Jeletzky (1966) established the family Groenlandibelidae. Today, four species in three genera can reliably be placed within this spirulid family (Fuchs et al. 2012). Groenlandibelidae differ from belemnoids by the presence of a caecum, a narrow rod-like proostracum, wide soft tissue attachment scars, and the absence of a solid rostrum and tabular nacre in the shell wall (Fuchs et al. 2012). In contrast to Cenozoic spirulids (e.g. Beloptera, Spirulirostra), groenlandibelid phragmocones are not yet coiled.
The origin of groenlandibelids is still enigmatic. Morphologically, Cenomanian-Maastrichtian “Naefia” matsumotoi and Aptian "Naefia" kabanovi appear to be intermediate between belemnoid diplobelids and spirulids (Fuchs & Tanabe 2010, Fuchs et al., in revision).
Soft tissues are unknown from the fossil record.
Classification
- Groenlandibelidae Jeletzky, 1966
- Groenlandibelus Jeletzky, 1966
- Groenlandibelus rosenkrantzi (Birkelund, 1956) (Maastrichtian of Greenland)
- Naefia Wetzel, 1930
- Naefia neogaeia Wetzel, 1930 (Maastrichtian of Chile)
- Cyrtobelus Fuchs et al., 2012
- Cyrtobelus birkelundae Fuchs et al., 2012 (Maastrichtian of Greenland)
- Cyrtobelus hornbyense Fuchs et al., 2012 (Campanian of Canada)
- Family and order uncertain
- "Naefia" matsumotoi (Hirano et al., 1991) (?Albian, Cenomanian-Maastrichtian of Japan)
- "Naefia" kabanovi (Doguzhaeva, 1996) (Aptian of Caucasus)
References
Fuchs, D., Keupp, H., Trask, P. and Tanabe, K. 2012. Taxonomy, morphology and phylogeny of Late Cretaceous spirulid coleoids (Cephalopoda) from Greenland and Canada. Palaeontology. DOI: 10.1111/j.1475-4983.2011.01125.x
Fuchs, D. and Tanabe, K. 2010. Re-investigation of the shell morphology and ultrastructure of the late Cretaceous spirulid coleoid Naefia matsumotoi. In: Proceedings of the 7th International Symposium - Cephalopods - Present & Past, Sapporo. 195-207.
Jeletzky, J. A. 1966. Comparative morphology, phylogeny and classification of fossil Coleoidea. Paleontological Contributions, University of Kansas, Mollusca, 7, 1?166.
About This Page
Dirk Fuchs
Free University Berlin, Institut of Geological Sciences
Correspondence regarding this page should be directed to Dirk Fuchs at
Page copyright © 2012 Dirk Fuchs
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- First online 04 July 2012
- Content changed 04 July 2012
Citing this page:
Fuchs, Dirk. 2012. Cretaceous spirulids. Version 04 July 2012 (under construction). http://tolweb.org/Cretaceous_spirulids/148172/2012.07.04 in The Tree of Life Web Project, http://tolweb.org/