Original paper
Ammonoids: the ultimate in biostratigraphy
Korn, Dieter; Brayard, Arnaud; Lehmann, Jens; Page, Kevin N.
Newsletters on Stratigraphy (2025)
306 references
published online: Jul 2, 2025
manuscript accepted: May 21, 2025
manuscript revision requested: Apr 10, 2025
manuscript received: Feb 6, 2025
Abstract
Ammonoids have long held a central position in stratigraphic research, having served as one of the principal fossil groups since the early development of the discipline. These extinct cephalopods developed a rich morphological diversity with exceptionally high evolutionary rates, resulting in a rapid turnover of species. From the Early Devonian through to the end of the Cretaceous, ammonoids were one of the most important groups for the subdivision of sedimentary sequences. In recent decades, however, their dominance in biostratigraphy has diminished in favour of other fossil groups, particularly microfossils. Despite this, ammonoids still play a crucial role in the regional definition of very short stratigraphic intervals. In many cases, their precision in stratigraphic subdivision exceeds that of both macrofossil and microfossil groups. Ammonoids remain unparalleled in their utility for stratigraphic schemes, especially in the Late Devonian, selected intervals of the Carboniferous and Triassic, the entire Jurassic and parts of the Cretaceous. Stratigraphic units based on ammonoids are sometimes between 50 kyr and 100 kyr in duration. However, the often-limited geographic distribution of ammonoid species restricts their potential for interregional or global correlation.
Keywords
Ammonoida • biostratigraphy • Devonian • Carboniferous • Permian • Triassic • Jurassic • Cretaceous