Closeup of a fossilized ammonite from the Jurrasic era at El Torcal de Antequera nature reserve, located south of the city of Antequera, Spain
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 (, 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).
Size: 5760px × 3840px
Location: El Torcal de Antequera, province of Malaga, Andalusia, Spain, southern Europe
Photo credit: © DE ROCKER / Alamy / Afripics
License: Licensed
Model Released: No
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