''Tropaeum'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

ammonite 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) ...

s found throughout the oceans of the world during the Early

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 ...

. As with many other members of the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Ancyloceratidae, there was a trend among species within this genus to uncoil somewhat, in a very similar manner to the genus ''

Lytoceras ''Lytoceras'' is an ammonite genus that was extant during most of the Jurassic and Cretaceous periods, and is the type genus for the family Lytoceratidae. These cephalopods were fast-moving nektonic carnivores. Description Shells of ''Lytoceras' ...

''. The largest species, ''T. imperator'' of

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

, had a shell a little over one meter in diameter. The name "Tropaeum" was applied by paleontologist

James De Carle Sowerby James De Carle Sowerby (5 June 1787 – 26 August 1871) was a British mineralogist, botanist, and illustrator. He received an education in chemistry. Sowerby was born in London, the son of botanical artist James Sowerby (1757–1822), and hi ...

, in 1837.

References

External links

* photograph of the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

of ''T. imperator'

Ammonitida genera Early Cretaceous ammonites Ammonites of Australia Ancyloceratoidea {{Ammonite-stub