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Evolutionary trends in the elasmobranch neurocranium.
Joel H Gayford1,2, Martin D Brazeau3,4, Gavin J P Naylor5
1Department of Life Sciences, Silwood Park Campus, Imperial College London, London, UK. jhg19@ic.ac.uk.
Scientific Reports
|May 20, 2024
Summary
Shark and ray braincase evolution shows mosaic patterns, with jaw suspension innovations driving ecological diversification. Water depth and biogeography significantly influence elasmobranch cranial diversity.
Area of Science:
- Vertebrate Paleontology
- Evolutionary Biology
- Comparative Anatomy
Background:
- The neurocranium (braincase) is crucial for housing the brain and sensory organs, influencing body shape and jaw articulation.
- Elasmobranchii (sharks and rays) offer a unique model for studying braincase diversity due to their simplified cranial structure.
- Understanding the link between elasmobranch braincase shape and ecology is vital for insights into form-function relationships.
Purpose of the Study:
- To investigate patterns of mosaic cranial evolution in Elasmobranchii.
- To explore the associations between elasmobranch braincase shape and ecological factors.
- To determine the influence of jaw suspension innovation on cranial integration and modularity.
Main Methods:
- Comparative analysis of neurocranial morphology across Elasmobranchii.
- Phylogenetic reconstruction to infer evolutionary patterns.
- Correlation analysis between cranial shape, ecology, water depth, and biogeography.
Main Results:
- Elasmobranchii exhibit mosaic cranial evolution distinct from other vertebrate clades.
- Evolutionary modularity differs between Selachii (sharks) and Batoidea (rays).
- Jaw suspension innovations appear to drive shifts in cranial integration and modularity, facilitating ecological diversification.
Conclusions:
- Water depth and biogeography are significant drivers of elasmobranch cranial diversity.
- Skeletal articulation between the neurocranium and jaws acts as a major evolutionary constraint on braincase shape.
- Cranial modularity and integration patterns in elasmobranchs are influenced by jaw suspension evolution and ecological pressures.
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