''Hamulina'' is an extinct

ammonoid Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ...

cephalopod genus belonging to the family

Hamulinidae Hamulinidae is an extinct Ammonoidea, ammonoid cephalopod family belonging to the order Ammonitida. with and (1996), ''Mollusca 4 Revised , Cretaceous Ammonoidea'', vol. 4, in ''Treatise on Invertebrate Paleontology'', Part L (Roger L. Kaesl ...

. with and (1996), ''Mollusca 4 Revised , Cretaceous Ammonoidea'', vol. 4, in ''Treatise on Invertebrate Paleontology'', Part L (Roger L. Kaesler et el. eds.), Boulder, Colorado: The Geological Society of America & Lawrence, Kansas: University of Kansas Press, pp. 231, 232. These cephalopod were fast-moving nektonic carnivores. They lived during the Cretaceous period,

Barremian The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 129.4 ± 1.5 Ma (million years ago) and 121.4 ± 1.0 Ma). It is a subdivision of the Early Cretaceous Epoch (or Lower Cretaceous Series). It is preceded ...

age. The type species is ''Hamulina astieriana''.

Description

It may be large. The whorl section generally is increasing rapidly. The short final shaft is generally straight or curved. The main shaft is with dense, fine, prorsiradiate minor ribs and distant, periodic, weakly trituberculate major ribs. The minor ribs are weakened or disappearing on hook and final shaft. The major ribs are strengthened and approximating. The ammonitic suture is finely divided.

Distribution

Fossils of these cephalopods have been found in rocks of

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

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( Santa Rosa de Viterbo, Boyacá),

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. File:Hamulinidae - Hamulina astieri.JPG, ''Hamulina astieri'' from southern

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, on display at Galerie de paléontologie et d'anatomie comparée, Paris File:Hamulina pamuktschiensis sp.n., Lower Barremian, Pamuktschii - SUMPHG.jpg, ''Hamulina pamuktschiensis sp.n.'', Lower

, Pamuktschii at the Sofia University "St. Kliment Ohridski" Museum of Paleontology and Historical Geology

Description

Distribution

References

Further reading