In the present study, a series of phylogenetic analyses of morphological, molecular, and combined morphological-molecular datasets were conducted to investigate the relationships of 23 extant and 44 fossil caniforme genera, in order to test the phylogenetic position of putative stem pinniped Puijila within a comprehensive evolutionary framework. With Canis as an outgroup, a Bayesian Inference analysis employing tip-dating of a combined molecular-morphological (i.e., Total Evidence) dataset recovered a topology in which musteloids are the sister group to a monophyletic pinniped clade, to the exclusion of ursids, and recovered Puijila and Potamotherium along the stem of Pinnipedia. A similar topology was recovered in a parsimony analysis of the same dataset. These results suggest the pinniped stem may be expanded to include additional fossil arctoid taxa, including Puijila, Potamotherium, and Kolponomos. The tip-dating analysis suggested a divergence time between pinnipeds and musteloids of ∼45.16 million years ago (Ma), though a basal split between otarioids and phocids is not estimated to occur until ∼26.52 Ma. These results provide further support for prolonged freshwater and nearshore phases in the evolution of pinnipeds, prior to the evolution of the extreme level of aquatic adaptation displayed by extant taxa. Ancestral character state reconstruction was used to investigate character evolution, to determine the frequency of reversals and parallelisms characterizing the three extant clades within Pinnipedia. Although the phylogenetic analyses did not directly provide any evidence of parallel evolution within the pinniped extant families, it is apparent from the inspection of previously-proposed pinniped synapomorphies, within the context of a molecular-based phylogenetic framework, that many traits shared between extant pinnipeds have arisen independently in the three clades. Notably, those traits relating to homodonty and limb-bone specialization for aquatic locomotion appear to have multiple origins within the crown group, as suggested by the retention of the plesiomorphic conditions in early-diverging fossil members of the three extant families. Thus, while the present analysis identifies a new suite of morphological synapomorphies for Pinnipedia, the frequency of reversals and other homoplasies within the clade limit their diagnostic value.

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Until now, the pre-Miocene fossil record of mustelids in North America has been restricted to specimens attributable to oligobunine taxa and isolated remains tentatively allocated to the genus Plesictis. In the present study, we report on a nearly complete cranium and a referred dentary of a new genus and species of mustelid. The specimens were recovered from the Turtle Cove and Kimberly Members of the John Day Formation, Oregon, USA. These excellently preserved specimens more confidently confirm the presence of mustelids in the Early and Late Oligocene (Early and Late Arikareean) of North America. Like the holotype specimen of ‘Plesictis’ julieni, the new species lacks an alisphenoid canal and a postprotocrista on the M1 (synapomorphies of Mustelidae), but retains a dorsally deep suprameatal fossa (a feature occasionally suggested to be unique to Procyonidae). Phylogenetic analyses, applying parsimony and Bayesian inference to combined molecular (five genes totalling 5490 bp) and morphological data, recover this new species of mustelid as sister-species to ‘Plesictis’ julieni. The results of these analyses reveal that the new genus is a close relative of other species of Plesictis and several taxa traditionally allied with Oligobuninae, thereby rendering Oligobuninae paraphyletic. We further discuss the significance of the relatively small size of this new mustelid as it relates to predictions based on increased aridification of the palaeoclimate and the expansion of open habitats in the Oligocene.

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.iii

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