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Bicknell RDC, Schmidt M, Rahman IA, Edgecombe GD, Gutarra S, Daley AC, Melzer RR, Wroe S, Paterson JR. Raptorial appendages of the Cambrian apex predator Anomalocaris canadensis are built for soft prey and speed. Proc Biol Sci 2023; 290:20230638. [PMID: 37403497 DOI: 10.1098/rspb.2023.0638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/06/2023] Open
Abstract
The stem-group euarthropod Anomalocaris canadensis is one of the largest Cambrian animals and is often considered the quintessential apex predator of its time. This radiodont is commonly interpreted as a demersal hunter, responsible for inflicting injuries seen in benthic trilobites. However, controversy surrounds the ability of A. canadensis to use its spinose frontal appendages to masticate or even manipulate biomineralized prey. Here, we apply a new integrative computational approach, combining three-dimensional digital modelling, kinematics, finite-element analysis (FEA) and computational fluid dynamics (CFD) to rigorously analyse an A. canadensis feeding appendage and test its morphofunctional limits. These models corroborate a raptorial function, but expose inconsistencies with a capacity for durophagy. In particular, FEA results show that certain parts of the appendage would have experienced high degrees of plastic deformation, especially at the endites, the points of impact with prey. The CFD results demonstrate that outstretched appendages produced low drag and hence represented the optimal orientation for speed, permitting acceleration bursts to capture prey. These data, when combined with evidence regarding the functional morphology of its oral cone, eyes, body flaps and tail fan, suggest that A. canadensis was an agile nektonic predator that fed on soft-bodied animals swimming in a well-lit water column above the benthos. The lifestyle of A. canadensis and that of other radiodonts, including plausible durophages, suggests that niche partitioning across this clade influenced the dynamics of Cambrian food webs, impacting on a diverse array of organisms at different sizes, tiers and trophic levels.
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Affiliation(s)
- Russell D C Bicknell
- Palaeoscience Research Centre, School of Environmental and Rural Science, University of New England, Armidale 2351, Australia
- Division of Paleontology, American Museum of Natural History, New York, NY 10027, USA
| | - Michel Schmidt
- Bavarian State Collection of Zoology, Bavarian Natural History Collections, Munich, Germany
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, North Cuihu Road 2, Kunming 650091, People's Republic of China
| | - Imran A Rahman
- The Natural History Museum, Cromwell Road, London SW7 5BD, UK
- Oxford University Museum of Natural History, Oxford OX1 3PW, UK
| | | | - Susana Gutarra
- The Natural History Museum, Cromwell Road, London SW7 5BD, UK
| | - Allison C Daley
- Institute of Earth Sciences, University of Lausanne, Lausanne CH-1015, Switzerland
| | - Roland R Melzer
- Bavarian State Collection of Zoology, Bavarian Natural History Collections, Munich, Germany
- Faculty of Biology, Biocenter, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
- GeoBio-Center, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Stephen Wroe
- Palaeoscience Research Centre, School of Environmental and Rural Science, University of New England, Armidale 2351, Australia
- Function, Evolution and Anatomy Research Lab, School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia
| | - John R Paterson
- Palaeoscience Research Centre, School of Environmental and Rural Science, University of New England, Armidale 2351, Australia
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