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Cleoniceras cleon Ammonite a.jpg

Dpaul7

By Dpaul7

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Cleoniceras cleon Ammonite
 
Madagascar
TIME PERIOD: Cretaceous Period (150 Million Years)
Cleoniceras is a rather involute, high-whorled hoplitid from the Lower to basal Middle Albian of Europe, Madagascar, and Transcaspian region. The shell has a generally small umbilicus, arched to acute venter, and typically at some growth stage, falcoid ribs that spring in pairs from umbilical tubercles, usually disappearing on the outer whorls. Ammonoids are an extinct group of marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs are more closely related to living coleoids (i.e., octopuses, squid, and cuttlefish) than they are to shelled nautiloids such as the living Nautilus species. The earliest ammonites appear during the Devonian, and the last species died out during the Cretaceous–Paleogene extinction event. Ammonites are excellent index fossils, and it is often possible to link the rock layer in which a particular species or genus is found to specific geologic time periods. Their fossil shells usually take the form of planispirals, although there were some helically spiraled and nonspiraled forms (known as heteromorphs). The name "ammonite", from which the scientific term is derived, was inspired by the spiral shape of their fossilized shells, which somewhat resemble tightly coiled rams' horns. Pliny the Elder (d. 79 AD near Pompeii) called fossils of these animals ammonis cornua ("horns of Ammon") because the Egyptian god Ammon (Amun) was typically depicted wearing ram's horns. Often the name of an ammonite genus ends in -ceras, which is Greek for "horn". *NOTE: This specimen has been split to show the inner chambers.
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Order: †Ammonitida
Family: †Cleoniceratidae or †Hoplitidae (disputed)
Genus: †Cleoniceras
Species: †cleon

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Photo Information

  • Taken with Canon Canon PowerShot SX120 IS
  • Focal Length 6 mm
  • Exposure Time 1/60
  • f Aperture f/2.8
  • ISO Speed 80
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