Ammonietsoorten

Ammonietsoorten refers to the diverse classification of extinct marine cephalopod mollusks belonging to the subclass Ammonoidea. These creatures, which lived from the Devonian period to the end of the Cretaceous period, are characterized by their coiled, chambered shells. The study of ammonietsoorten is crucial for understanding prehistoric marine ecosystems and for biostratigraphy, as their rapid evolution and widespread distribution make them excellent index fossils.

The classification of ammonietsoorten is based on the intricate patterns of their suture lines, which are the lines where the internal walls of the shell chambers meet the outer shell wall. These patterns, visible when a shell is broken open, vary significantly between different groups and species. Morphological features such as shell coiling (planispiral, evolute, involute), ribbing, and the presence of spines or other ornamentation also play a role in identification.

Over millions of years, ammonietsoorten evolved into thousands of distinct species, adapting to various marine environments. From the early, simpler coiled forms, they diversified into highly complex shapes and suture patterns. Major groups include the Goniatitida, Ceratitida, and Phylloceratida, each representing different evolutionary lineages and time spans within the Mesozoic Era. The extinction of ammonietsoorten coincided with the Cretaceous-Paleogene extinction event, marking the end of their long reign in the oceans. Their fossilized shells are found globally, providing invaluable insights into ancient life and geological history.