Youngibelus
Youngibelus is a genus of belemnite, an extinct group of cephalopods.[1]
| Youngibelus Temporal range: Jurassic | |
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| Two Youngibelus, showing the male on the bottom with an epirostrum | |
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| Family: | Belemnitidae |
| Subfamily: | Megateuthidinae |
| Genus: | Youngibelus Riegraf, 1980 |
Sexual Dimorphism
Y.tubularis and Y.levis are two species from Toarcian aged rocks in Yorkshire. It has been suggested that these two species are actually morphs of the same species. The divergence in morphology occurs in the gerontic stage of development, characterised by differences in the rostrum. In Y.levis, the rostrum thickens, whilst in Y.tubularis, an epirostrum develops. Peter Doyle proposed that the epirostrum developed as either a counterbalance for a sexual adaptation, or for display in courtship[2]
See also
- Belemnite
- List of belemnites
References
- Sepkoski, Jack (2002). "A compendium of fossil marine animal genera (Cephalopoda entry)". Bulletins of American Paleontology. 364: 560. Retrieved 2009-04-10.
- Doyle, Peter (1985). "Sexual dimorphism in the belemnite Youngibelus from the Lower Jurassic of Yorkshire". Retrieved 13th May 2020
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