Evidence for the independent acquisition of aquatic specializations in pinnipeds (seals, sea lions, and walruses): insights from the study of the phylogenetic position, locomotor behaviour, and description of the stem pinniped, Puijila darwini

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Creator: 

Paterson, Ryan

Date: 

2017

Abstract: 

Monophyly of pinnipeds (seals, sea lions, and walruses) is well-established. However, it is difficult to reconcile a monophyletic origin of pinnipeds with the disparate locomotory modes and associated skeletal morphologies observed between the extant families. In this study, the skeletal anatomy of Puijila darwini, a key putative stem pinniped from Canada’s High Arctic, is fully described. A biomechanical analysis, using functional limb indices of extant carnivorans to predict locomotory modes in extinct taxa, confirms the aquatic adaptations of Puijila, and identifies it as a forelimb-dominated swimmer. Phylogenetic analyses of molecular and morphological data in isolation recover Puijila as a stem pinniped, and provide strong support for pinniped monophyly. However, a phylogenetic analysis combining molecular and morphological data together recovers an unconventional topology, suggesting the molecular and morphological data are incongruent. Closer scrutiny of previously-proposed pinniped synapomorphies suggests many features shared between seals, sea lions, and walruses arose in parallel.

Subject: 

Paleontology
Bioinformatics
Anatomy

Language: 

English

Publisher: 

Carleton University

Thesis Degree Name: 

Master of Science: 
M.Sc.

Thesis Degree Level: 

Master's

Thesis Degree Discipline: 

Earth Sciences

Parent Collection: 

Theses and Dissertations

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