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Belemnitida
| Belemnites | |
|---|---|
| |
| The Early Jurassic Passaloteuthis bisulcata showing soft anatomy | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Superorder: | †Belemnoidea |
| Order: | †Belemnitida Zittel, 1895 |
| Suborders | |
Belemnitida (or belemnites) is an extinct order of squid-like cephalopods that existed from the Late Triassic to Late Cretaceous (And possibly the Eocene[4][5]). Unlike squid, belemnites had an internal skeleton that made up the cone. The parts are, from the arms-most to the tip: the tongue-shaped pro-ostracum, the conical phragmocone, and the pointy guard. The calcitic guard is the most common belemnite remain. Belemnites, in life, are thought to have had 10 hooked arms and a pair of fins on the guard. The chitinous hooks were usually no bigger than 5 mm (0.20 in), though a belemnite could have had between 100 and 800 hooks in total, using them to stab and hold onto prey.
Belemnites were an important food source for many Mesozoic marine creatures, both the adults and the planktonic juveniles and they likely played an important role in restructuring marine ecosystems after the Triassic–Jurassic extinction event. They may have laid between 100 and 1,000 eggs. Some species may have been adapted to speed and swam in the turbulent open ocean, whereas others resided in the calmer littoral zone (nearshore) and fed off the seafloor. The largest belemnite known, Megateuthis elliptica, would have measured up to 3.11 metres (10.2 ft) in total body length.[6]
Belemnites were coleoids, a group that includes squid and octopuses, and are often grouped into the superorder Belemnoidea, though the higher classification of cephalopods is volatile and there is no clear consensus on how belemnites are related to modern coleoids. Guards can give information on the climate, habitat, and carbon cycle of the ancient waters they inhabited. Guards have been found since antiquity and have become part of folklore.[7][8]
- ^ Iba, Y.; Sano, S. -I.; Mutterlose, J.; Kondo, Y. (2012). "Belemnites originated in the Triassic—A new look at an old group". Geology. 40 (10): 911–914. Bibcode:2012Geo....40..911I. doi:10.1130/G33402.1.
- ^ Macleod, N.; Rawson, P. F.; Forey, P. L.; Banner, F. T.; Boudagher-Fadel, M. K.; Bown, P. R.; Burnett, J. A.; Chambers, P.; Culver, S.; Evans, S. E.; Jeffery, C.; Kaminski, M. A.; Lord, A. R.; Milner, A. C.; Milner, A. R. (1997). "The Cretaceous-Tertiary biotic transition". Journal of the Geological Society. 154 (2): 265–292. doi:10.1144/gsjgs.154.2.0265. ISSN 0016-7649.
- ^ Reitner, J.; Engeser, T. (1982-12-22). "Phylogenetic trends in phragmocone-bearing coleoids (Belemnomorpha)". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen. 164 (1–2): 156–162. doi:10.1127/njgpa/164/1982/156. ISSN 0077-7749.
- ^ Cite error: The named reference
macleodwas invoked but never defined (see the help page). - ^ Cite error: The named reference
:0was invoked but never defined (see the help page). - ^ Klug, C.; Schweigert, G.; Hoffmann, R.; Fuchs, D.; Pohle, A.; Weis, R.; De Baets, K. (2024). "Anatomy and size of Megateuthis, the largest belemnite". Swiss Journal of Palaeontology. 143 (1). 23. doi:10.1186/s13358-024-00320-x. PMC 11139743.
- ^ Wilkin, J.T.R. (2022). "Fossils explained 82: Belemnites: Anatomy, ecology, applications". Geology Today. 38 (5): 194–200. Bibcode:2022GeolT..38..194W. doi:10.1111/gto.12409. S2CID 252847710.
- ^ Wilkin, J.T.R. (2021). "Belemnites in Mythology: From Thunderstorms to Fertility Symbols". EGU Blog: Stratigraphy, Sedimentology and Palaeontology. Retrieved 2022-11-02.
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