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Modern pinnipeds (seals, sea lions and the walrus) are semi-aquatic, generally marine carnivores the limbs of which have been modified into flippers. Recent phylogenetic studies using morphological and molecular evidence support pinniped monophyly, and suggest a sister relationship with ursoids (1,2) (for example bears) or musteloids (3-7) (the Glade that includes skunks, badgers, weasels and otters). Although the position of pinnipeds within modern carnivores appears moderately well resolved, fossil evidence of the morphological steps leading from a terrestrial ancestor to the modern marine forms has been weak or contentious. The earliest well-represented fossil pinniped is Enaliarctos, a marine form with flippers, which had appeared on the northwestern shores of North America by the early Miocene epoch (8,9). Here we report the discovery of a nearly complete skeleton of a new semi-aquatic carnivore from an early Miocene lake deposit in Nunavut, Canada, that represents a morphological link in early pinniped evolution. The new taxon retains a long tail and the proportions of its fore- and hindlimbs are more similar to those of modern terrestrial carnivores than to modern pinnipeds. Morphological traits indicative of semi-aquatic adaptation include a forelimb with a prominent deltopectoral ridge on the humerns, a posterodorsally expanded scapula, a pelvis with relatively short ilium, a shortened femur and flattened phalanges, suggestive of webbing. The new fossil shows evidence of pinniped affinities and similarities to the early Oligocene Amphicticeps from Asia and the late Oligocene and Miocene Potamotherium from Europe. The discovery suggests that the evolution of pinnipeds included a freshwater transitional phase, and may support the hypothesis that the Arctic was an early centre of pinniped evolution., Among mammals, the land-to-sea transition has occurred several times with varying completeness, as shown by cetaceans, sirenians, desmostylians, pinnipeds and sea otters. This transition is characterized by innovations associated with [...]

Primate fauna from southeastern China belong to the Eocene period and possess greater diversity than periodic counterparts obtained from European and North American sites. The primates possess distinct affinities with European taxa although the Europolemur-like species may be related to North American forms. The trasiid is endemic in the samples. Basal simian radiation may suggest a Paleocene biogeographic link with Africa.

Discoveries of the dental remains of a primitive rodent from Inner Mongolia, China, helps understand rodent origin, its relationship with other eutherian mammals and rodent monophyly. The studies suggest reevaluation of phylogenetic attractions within gliriform eutherians and implies a relationship between lagomorphs and rodents.