ammonitic

Ammonitic is an adjective used in paleontology and related fields to describe ammonites or features derived from them. It most often refers to the highly complex suture pattern found in the shells of many ammonoid species, and less commonly to the shells themselves. The term is derived from Ammonites, the fossil group named after the ancient Egyptian deity Amun (Ammon).

In paleontological usage, ammonitic sutures are characterized by intricate, highly folded lobes and saddles that create a frilled, ornate appearance along the shell’s outer edge. This pattern contrasts with goniatitic sutures, which are simpler and less lobed, and ceratitic sutures, which have well-defined lobes with serrated or frilled saddles. The ammonitic pattern is associated with a broad range of ammonoid taxa and is a key diagnostic feature in many taxa.

Ammonitic features are employed in taxonomic classification and biostratigraphy. The detailed morphology of sutures aids in distinguishing species and genera, and variation in sutural patterns can help correlate rock units across geographic regions. Because ammonites are widely used as index fossils, ammonitic characteristics often contribute to age-dating and regional stratigraphic correlation, alongside other shell features and foraminal or microstructural data.

See also Ammonoidea, ammonites, and sutural patterns in cephalopods.