Journal article
Did shell-crushing predators drive the evolution of ammonoid septal shape?
PALEOBIOLOGY, v 47(4), pp 666-679
Nov 2021
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
For centuries, paleontologists have sought functional explanations for the uniquely complex internal walls (septa) of ammonoids, extinct shelled cephalopods. Ammonoid septa developed increasingly complex fractal margins, unlike any modern shell morphologies, throughout more than 300 million years of evolution. Some have suggested these morphologies provided increased resistance to shell-crushing predators. We perform the first physical compression experiments on model ammonoid septa using controlled, theoretical morphologies generated by computer-aided design and 3D printing. These biomechanical experiments reveal that increasing complexity of septal margins does not increase compression resistance. Our results raise the question of whether the evolution of septal shape may be tied closely to the placement of the siphuncle foramen (anatomic septal hole). Our tests demonstrate weakness in the centers of uniformly thick septa, supporting work suggesting reinforcement by shell thickening at the center of septa. These experiments highlight the importance of 3D reconstruction using idealized theoretical morphologies that permit the testing of long-held hypotheses of functional evolutionary drivers by recreating extinct morphologies once rendered physically untestable by the fossil record.
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Details
- Title
- Did shell-crushing predators drive the evolution of ammonoid septal shape?
- Publication Details
- PALEOBIOLOGY, v 47(4), pp 666-679
- Publisher
- CAMBRIDGE UNIV PRESS; NEW YORK
- Number of pages
- 13
- Grant note
- We thank P. Dodson, D. Jerolmack, and H. Pfefferkorn for helpful comments and discussions. We also thank D. Vann and S. Szewczyk for assistance with lab equipment. This research was in part supported by funding through the National Science Foundation Graduate Research Fellowship Program (DGE-1845298). Additionally, internal funding was provided by the Greg and Susan J. Walker Foundation and the Summer Research Stipend in Paleontology (Department of Earth and Environmental Science at the University of Pennsylvania). Delaware Valley Paleontological Society also supported this project through the Paul Bond Scholarship fund. The authors declare no competing interests.
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Drexel University
- Web of Science ID
- WOS:000723750300009
- Scopus ID
- 2-s2.0-85120871766
- Other Identifier
- 991021860756804721
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- Collaboration types
- Domestic collaboration
- Web of Science research areas
- Biodiversity Conservation
- Ecology
- Evolutionary Biology
- Paleontology