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The polyphasic ontogeny of the discoidal Late Devonian ammonoid Acrimeroceras


Buchwald, Stella Zora; Klug, Christian; Korn, Dieter (2019). The polyphasic ontogeny of the discoidal Late Devonian ammonoid Acrimeroceras. PalZ Paläontologische Zeitschrift:Epub ahead of print.

Abstract

The Late Devonian ammonoid species Acrimeroceras falcisulcatum and A. stella have similar-shaped discoidal adult conchs. Their conch morphology and its ontogenetic development are described and analysed. Despite great similarities in their adult conch morphology, they can be clearly distinguished by differences in the shape of their juvenile whorl profile and by the growth trajectories of their cardinal conch parameters: conch width index, umbilical width index and whorl expansion rate. Quantification of ontogenetic change in the two species demonstrates that the stratigraphically younger species A. falcisulcatum possesses the less complex ontogeny compared to the stratigraphically older A. stella. The closely related genus Paratornoceras (early Famennian) and the unrelated Late Viséan Calygirtyoceras show juvenile conch morphology and ontogenetic trajectories very similar to Acrimeroceras stella. This similarity can be seen as iterative independent unfolding of homoplastic characters, possibly linked to size-dependence of the functional morphology of the conchs.
Keywords Devonian · Ammonoidea · Ontogeny · Allometry · Morphometry

Abstract

The Late Devonian ammonoid species Acrimeroceras falcisulcatum and A. stella have similar-shaped discoidal adult conchs. Their conch morphology and its ontogenetic development are described and analysed. Despite great similarities in their adult conch morphology, they can be clearly distinguished by differences in the shape of their juvenile whorl profile and by the growth trajectories of their cardinal conch parameters: conch width index, umbilical width index and whorl expansion rate. Quantification of ontogenetic change in the two species demonstrates that the stratigraphically younger species A. falcisulcatum possesses the less complex ontogeny compared to the stratigraphically older A. stella. The closely related genus Paratornoceras (early Famennian) and the unrelated Late Viséan Calygirtyoceras show juvenile conch morphology and ontogenetic trajectories very similar to Acrimeroceras stella. This similarity can be seen as iterative independent unfolding of homoplastic characters, possibly linked to size-dependence of the functional morphology of the conchs.
Keywords Devonian · Ammonoidea · Ontogeny · Allometry · Morphometry

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Paleontological Institute and Museum
Dewey Decimal Classification:560 Fossils & prehistoric life
Uncontrolled Keywords:Palaeontology
Language:English
Date:12 December 2019
Deposited On:13 Jan 2020 11:32
Last Modified:04 Mar 2020 16:25
Publisher:Springer
ISSN:0031-0220
OA Status:Closed
Publisher DOI:https://doi.org/10.1007/s12542-019-00497-4

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