Date of Award
Summer 8-20-2023
Degree Type
Thesis
Degree Name
Master of Science (MS)
Department
Biological Science
First Advisor
Windsor Aguirre, PhD
Second Advisor
Eric Norstrom, PhD
Third Advisor
Kenshu Shimada, PhD
Abstract
Sharks occupy a wide range of ecological niches and lifestyle strategies attributed to their complex sensory system housed in their neurocranium. However, the diversity of neurocranial morphology in sharks and how the diversity may be related to their sensory capability have never been adequately surveyed. Therefore, the aims of this present study were: 1) to examine whether the relative sizes of rostral, olfactory, optic, and/or otic regions of neurocrania in sharks are related to their habitat, diet, and/or body form types; and 2) to investigate any possible patterns and insights into the ecology and evolution of sharks on the basis of neurocranial diversity. My primary dataset comprised neurocrania of 182 extant species in 37 families and 102 genera, along with 10 extinct elasmobranch taxa, representing the most comprehensive survey of the neurocranial diversity of sharks to date. My study suggests that there is a statistically significant difference between each of the four examined neurocranial regions and habitat, diet, and body form types, except for the relationship of the optic region size with the habitat types and body form types. My geometric morphometric analysis indicates that the rostral length and cranial width are the most variable parts of the shark neurocranium, where there appears to be only one general neurocranial morphology in sharks that is characterized by a relatively slender skull with a short rostrum. Whereas this morphological condition is regarded as plesiomorphic, my study reveals that the general neurocranial morphology could be evolutionarily modified in two different ways by elongating the rostrum or by broadening the cranial width. The skulls of most examined extinct sharks are represented by the generalized neurocranial morphology, but Lamniformes exhibit the greatest neurocranial diversity among all the shark orders examined. In addition to providing information about their ecology and evolutionary biology, my study offers new information that can be used for the conservation of sharks.
Recommended Citation
Wood, Jake J., "Morphological Diversity of Neurocrania in Sharks (Chondrichthyes: Elasmobranchii) and Its Ecological and Evolutionary Implications" (2023). College of Science and Health Theses and Dissertations. 562.
https://via.library.depaul.edu/csh_etd/562
SLP Collection
no
