#amoniti
- Acanthoceras — A genus of extinct fossil cephalopod mollusks (ammonites) within the Acanthoceratidae family, characteristic of the Late Cretaceous epoch. These marine organisms were distinguished by their massive, planospiral coiled shells heavily ornamented with prominent ribs and rows of sharp tubercles or spine-like outgrowths along the outer whorls, serving as critical index fossils for dating geological strata of that period.
- Ammonites — The plural form of amonit; an extensive group of fossil marine cephalopod mollusks characterized by chambered spiraled shells, similar to the modern nautilus. In historical geology, these representatives serve as essential index fossils for delineating and dating sedimentary biozones of past eras, providing clues about prehistoric ocean climate and dynamics.
- Ammonitids — Scientific name or comprehensive taxonomic classification (Ammonitida) that groups together the orders and families of true ammonites, characterized by shells with highly complex and branched suture lines. These fossil marine cephalopod mollusks dominated the seas during the Jurassic and Cretaceous periods, disappearing completely during the mass extinction at the end of the Mesozoic era.
- Archaic ammoniation — A historical or archaic term used in old 19th-century alchemy and chemistry treatises to designate the act of ammoniation, impregnation, or combination of a solid or liquid substance with ammonia vapors. This rudimentary process was applied in manufacturing workshops for fixing colors on textiles or in preparing early medicinal compounds.
- Anisian — A geological stage or substage located at the base of the Middle Triassic epoch, chronologically spanning from approximately 247 to 242 million years ago. As an adjective, the term refers to rocks, sediments, or fossils formed during this time interval, internationally defined by the appearance of specific ammonite and conodont assemblages within reference Alpine geological sections.
- Aptian — An upper geological stage of the Lower Cretaceous, chronologically situated between the Barremian and the Albian, structurally characterized by massive sedimentary deposits rich in ammonites and the expansion of specific marine faunas; as an adjective, it describes the rocks, formations, or fossils that formed during this period of Earth's history.