Westermann Morphospace displays ammonoid shell shape and hypothetical paleoecology

• Published in: Paleobiology Vol. 38; no. 3; pp. 424 - 446
• Main Authors: Ritterbush, Kathleen A, Bottjer, David J
• Format: Journal Article
• Language: English
• Published: New York, USA The Paleontological Society 01.06.2012; Cambridge University Press; Paleontological Society
• Subjects: Abundance; Ammonoidea; Anisian; biometry; Cephalopoda; Coiling; Data processing; Datasets; Early Jurassic epoch; Fossils; Geology; Geometric shapes; Hettangian; Invertebrata; invertebrate; Jurassic; Lower Jurassic; lower Liassic; Mesozoic; methods; Middle Triassic; Mollusca; Morphology; Ontogeny; Paleobiology; Paleoecology; Paleontology; s; Shells; Swimming; Taxonomy; Temporal variations; Treatises; Triassic; Umbilicus; Water column; Westermann morphospace
• ISSN: 0094-8373; 1938-5331
• DOI: 10.1666/10027.1

The Westermann Morphospace method displays fundamental morphotypes and hypothesized life modes of measured ammonoid fossils in a ternary diagram. It quantitatively describes shell shape, without assumption of theoretical coiling laws, in a single, easy-to-read diagram. This allows direct comparison between data sets presented in Westermann Morphospace, making it an ideal tool to communicate morphology. By linking measured shells to hypothesized life modes, the diagram estimates ecospace occupation of the water column. Application of this new method is demonstrated with Mesozoic data sets from monographs. Temporal variation, intraspecies variation, and ontogenetic variation are considered. This method can address hypothetical ecospace occupation in collections with tight stratigraphic, lithologic, and abundance control, even when taxonomy is in dispute.