The Origin and Evolutionary Biology of Pinnipeds: Seals, Sea Lions, and Walruses

2018 ◽  
Vol 46 (1) ◽  
pp. 203-228 ◽  
Author(s):  
Annalisa Berta ◽  
Morgan Churchill ◽  
Robert W. Boessenecker
Keyword(s):  
North Pacific ◽  
Evolutionary Biology ◽  
Breeding Systems ◽  
Feeding Strategies ◽  
Crown Group ◽  
Sea Lions ◽  
The North ◽  
Fur Seals ◽  
Body Sizes ◽  
The North Pacific

The oldest definitive pinniped fossils date from approximately 30.6–23 million years ago (Ma) in the North Pacific. Pinniped monophyly is consistently supported; the group shares a common ancestry with arctoid carnivorans, either ursids or musteloids. Crown pinnipeds comprise the Otariidae (fur seals and sea lions), Odobenidae (walruses), and Phocidae (seals), with paraphyletic “enaliarctines” falling outside the crown group. The position of extinct Desmatophocidae is debated; they are considered to be closely related to both otariids and odobenids or, alternatively, to phocids. Both otariids and odobenids are known from the North Pacific, diverging approximately 19 Ma, with phocids originating in the North Atlantic or Paratethys region 19–14 Ma. Our understanding of pinniped paleobiology has been enriched by studies that incorporate anatomical and behavioral data into a phylogenetic framework. There is now evidence for sexual dimorphism in the earliest pinnipeds, heralding polygynous breeding systems, followed by increased body sizes, diving capabilities, and diverse feeding strategies in later-diverging phocid and otarioid lineages.

scholarly journals The oldest record of the Steller sea lion Eumetopias jubatus (Schreber, 1776) from the early Pleistocene of the North Pacific

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9709
Author(s):  
Nahoko Tsuzuku ◽  
Naoki Kohno
Keyword(s):  
North Pacific ◽  
Japan Sea ◽  
Early Pleistocene ◽  
Steller Sea Lion ◽  
Eumetopias Jubatus ◽  
Sea Lion ◽  
Sea Lions ◽  
The North ◽  
Fur Seals ◽  
The North Pacific

The extant genera of fur seals and sea lions of the family Otariidae (Carnivora: Pinnipedia) are thought to have emerged in the Pliocene or the early Pleistocene in the North Pacific. Among them, the Steller sea lion (Eumetopias jubatus) is the largest and distributed both in the western and eastern North Pacific. In contrast to the limited distribution of the current population around the Japanese Islands that is now only along the coast of Hokkaido, their fossil records have been known from the middle and late Pleistocene of Honshu Island. One such important fossil specimen has been recorded from the upper lower Pleistocene Omma Formation (ca. 1.36–0.83 Ma) in Kanazawa, Ishikawa Prefecture, Japan, which now bears the institutional number GKZ-N 00001. Because GKZ-N 00001 is the earliest fossil having been identified as a species of the sea lion genus Eumetopias, it is of importance to elucidate the evolutionary history of that genus. The morphometric comparisons were made among 51 mandibles of fur seals and sea lions with GKZ-N 00001. As results of bivariate analyses and PCA based on 39 measurements for external morphologies with internal structures by CT scan data, there is almost no difference between GKZ-N 00001 and extant male individuals of E. jubatus. In this regard, GKZ-N 00001 is identified specifically as the Steller sea lion E. jubatus. Consequently, it is recognized as the oldest Steller sea lion in the North Pacific. About 0.8 Ma, the distribution of the Steller sea lion had been already established at least in the Japan Sea side of the western North Pacific.

scholarly journals The fur seals and fur-seal islands of the North Pacific ocean / By David Starr Jordan, [et al.]

1898 ◽  
Author(s):  
George Archilbald Clark ◽  
David Starr Jordan ◽  
Leonhard Stejneger ◽  
◽  
Keyword(s):  
Pacific Ocean ◽  
North Pacific ◽  
North Pacific Ocean ◽  
The North ◽  
Fur Seals ◽  
Fur Seal ◽  
The North Pacific

The Protection of Fur Seals in the North Pacific Ocean

Polar Record ◽  
1945 ◽  
Vol 4 (30) ◽  
pp. 264-271 ◽  
Author(s):  
Brian Roberts
Keyword(s):  
Pacific Ocean ◽  
North Pacific ◽  
North Pacific Ocean ◽  
Eastern Coast ◽  
Migration Route ◽  
Commander Islands ◽  
The North ◽  
Fur Seals ◽  
Breeding Grounds ◽  
The North Pacific

The fur seals of the North Pacific comprise three distinct herds, which do not intermingle in any way, having distinct breeding grounds, feeding grounds, and routes of migration. By far the most important of the three herds is that which resorts to the American Pribilof Islands. This herd breeds upon the islands of St Paul and St George during the summer, and in winter passes down through the channels of the Aleutian Islands into the Pacific Ocean. The migration reaches as far south as the coast of southern California and returns along the west coast of North America. The next herd in importance is that resorting to the Russian Komandorski (Commander) Islands. This breeds upon the islands of Beringa and Medni, passing in winter down along the eastern coast of Japan and returning by the same route. The third herd is resident in the Sea of Okhotsk on the Japanese Robben (Kaihyoto) Island, where a considerable remnant still exists. It formerly occupied other rookeries on four islands of the Japanese (formerly Russian) Kuril (Chishimi) group, but these are now virtually extinct. The migration route of this herd lies in the inland sea of Japan.

scholarly journals The fur seals and fur-seal islands of the North Pacific Ocean.

1898 ◽  
Author(s):  
◽  
George Archilbald Clark ◽  
W. W. Duffield ◽  
David Starr Jordan ◽  
Frederic A. Lucas ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
North Pacific ◽  
North Pacific Ocean ◽  
The North ◽  
Fur Seals ◽  
Fur Seal ◽  
The North Pacific
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