The invasion of the marine realm is one of the most dramatic ecological transitions in mammal evolution.
Pinnipeds (seals, sea lions and walruses) are an ideal case-study for understanding this transition because they are a diverse group, with a closely-related terrestrial outgroup.
My master's and subsequent work investigated morphological variation in pinnipeds, cranial adaptations to aquatic life and evolutionary patterns across the terrestrial-aquatic transition.
What functional and phylogenetic factors have shape the evolution of aquatic mammals?
I used geometric morphometrics to measure craniomandibular variation in pinnipeds, and test factors driving its evolution. I found strong phylogenetic signal, and extensive convergence for feeding and sexual display. Using beam modeling, I showed extreme sexual dimorphism of jaw function, and the importance of male combat in driving bite force evolution in the absence of mastication.
My work also highlighted enormous cranial diversity in pinnipeds, relative to other terrestrial carnivorans. I tested the hypothesis that this reflects an adaptive radiation at the base of the group. I examined rates and modes of evolution in terrestrial and aquatic carnivores. This study did not support an adaptive radiation. Instead it suggested that evolution in new morphological directions produced much of the diversity, followed by later evolutionary bursts within the aquatic environment.
Collaborators: Anjali Goswami, Jeroen Smaers, Chris Ruff, Jonathon Perry
Jones, K. E., Goswami, A. and Smaers, J. 2015. Impact of the terrestrial-aquatic transition on disparity and rates of evolution in the carnivoran skull. BMC Evolutionary Biology. 15(1):8.
Jones, K. E., Ruff, C. B. and Goswami. A. 2013. Biomechanics of the pinniped jaw: Mandibular evolution without mastication. Anatomical Record. 296(7):1049-1062.
Jones, K. E. and Goswami, A. 2010. Quantitative analysis of the influences of phylogeny and ecology on phocid and otariid pinniped (Mammalia; Carnivora) cranial morphology. Journal of Zoology. 280(3):297-308.
Jones, K. E. and Goswami, A. 2010. Morphometric analysis of cranial morphology in pinnipeds (Mammalia, Carnivora): convergence, ecology, ontogeny, and dimorphism. In: Goswami A. and Friscia A., editors. Carnivoran Evolution: New Views on Phylogeny, Form and Function. Cambridge University Press. p342-373.