Ammonoid morphological signal versus sea-level changes

Abstract

The morphological diversity, considered as a biological signal, of a series of four Upper Callovian (Middle Jurassic) ammonite populations of Côte-d'Or (France) is quantified. These populations fall within two third-order sequences of a second-order transgression. A sampling method that adheres as closely as possible to the morphological characteristics of the populations is established. It is valuable in that it eliminates the subjectivity related to taxonomy to allow more objective comparisons between the biological signal (shell morphology) and the physical signal (eustasy).

Ammonoid Habitats and Life History

“…This has consequences for the organisms living in the affected environment. Neige et al (1997) stressed the close relation between disparity and (eustatic) sea-level changes. These authors presented a new approach based on Callovian ammonoid faunas of France (Lominadze and Sakharov 1988, Callovian of Caucasus).…”

“…Biometric estimations (morphospace) by Neige et al (1997) on shell parameters including whorl expansion rate, diameter, whorl height and whorl width in Callovian ammonoids from France were used to relate morphology to sea-level changes. A clear trend was detected from subserpenticone (i.e., evolute, depressed, nektopelagic; Fig.…”

“…Information about the paleobiolgy of ammonoid assemblages can be gained in several ways. The first is a synoptic examination of the literature on ammonoid ecology dealing with morphology-habitat relations (Ziegler 1963(Ziegler , 1967Kauffmann 1977;Donovan 1985;Batt 1989Batt , 1993Jacobs et al 1994;Westermann 1996;Neige et al 1997;Navarro et al 2005). A second approach is to analyze the relation between the ammonoid fauna and the embedding facies (Chap.…”

“…Ammonoids have been used extensively by cephalopod researchers to correlate shell morphologies with environmental conditions (habitats), and distinct morphological groups were assigned to certain sea level changes, reflected by the lithology and facies (Ziegler 1963(Ziegler , 1967Tanabe 1979;Enay 1980;Donovan 1985;Marchand and Thierry 1986, Marchand 1992, Hantzpergue 1995, Westermann 1996, Neige et al 1997Klug 2002). Proxies for estimations related to shell morphology and the development of morphospace are ornament strength and whorl cross-section (e.g., circular, subtriangular, elliptic; depressed vs compressed etc.).…”

Temporal patterns in disparity and diversity of the Jurassic ammonoids of southern Germany

“…Neige et al 1997Neige et al , 2001Courville & CrÖnier 2005;Navarro et al 2005;Simon et al 2010), the research interest of this study is the analysis of morphospace dynamics in ammonoids from southern Germany compared to diversity changes over the Jurassic period. Furthermore, disparity and diversity changes are to be consulted for replication with changes that were postulated for Jurassic environments.…”