Can the intraspecific laws of variation be used as a predictive model for understanding species with insufficient data? The example of the early Heteroceratidae in their evolutionary context (heteromorph ammonites, Tethys upper Barremian) - INSU - Institut national des sciences de l'Univers Accéder directement au contenu
Article Dans Une Revue (Article De Synthèse) Cretaceous Research Année : 2023

Can the intraspecific laws of variation be used as a predictive model for understanding species with insufficient data? The example of the early Heteroceratidae in their evolutionary context (heteromorph ammonites, Tethys upper Barremian)

Résumé

The generalized ‘laws’ of intraspecific variability in ammonites are used as a predictive tool to define the limits of poorly known species of the early Heteroceratidae (Lazariniceras, heteromorph ammonites), based on the construction of the Heteroceras theoretical model of variation. The methodology is described and the model is confronted with the palaeontological data. The discussion of the results shows that the variability observed for Lazariniceras takes up most of the continuous variation of the theoretical model. To minimize bias, particular attention was paid to the strict stratigraphic control of the raw data (8 sections studied). Thus, and for the good application of the theoretical model, the stratigraphic canvas and the systematics of the groups studied were refined and discussed: (1) the abandonment of the Gerhardtia sartousiana Zone is proposed in favor of the new Camereiceras limentinum Zone; (2) Heteroceras astierianum, Heteroceras tardieui and Martelites bifurcatus are rehabilitated; and (3) Lazariniceras heterostylia sp. nov. and Lazariniceras lhaumeti sp. nov. are introduced while Lazariniceras astierianum is redefined. Once the theoretical model of the variation has been obtained, it was then possible to propose phylogenetic reconstruction hypotheses using the cladistic tool crossed with the stratigraphic data, used to study the evolutionary patterns and processes of the group. The results show that: (1) Lazariniceras is unambiguously a Heteroceratidae despite the absence of the early helical coiling; (2) Lazariniceras originates within the Toxancyloceras; (3) Ancyloceratidae is a paraphyletic taxon; (4) evolution of the studied group is expressed by changes in adult size, heterochronies and innovations.
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insu-04159637 , version 1 (12-07-2023)

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Didier Bert, Stéphane Bersac, Léon Canut, Bernard Beltrand. Can the intraspecific laws of variation be used as a predictive model for understanding species with insufficient data? The example of the early Heteroceratidae in their evolutionary context (heteromorph ammonites, Tethys upper Barremian). Cretaceous Research, 2023, 151, pp.105647. ⟨10.1016/j.cretres.2023.105647⟩. ⟨insu-04159637⟩
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