A new Miocene pinnipedAllodesmus(Mammalia: Carnivora) from Hokkaido, northern Japan

Abstract

A nearly complete pinniped skeleton from the middle Miocene Okoppezawa Formation (ca 16.3–13.9 Ma), Hokkaido, northern Japan, is described as the holotype of Allodesmus uraiporensis sp. nov. The new species is distinguishable from other species of the genus by having the palatine fissure (incisive foramen) that is located anterior to the canine, an anteriorly located supraorbital process of the frontal, and by having the calcaneum with a developed peroneal tubercle. Our phylogenetic analysis suggests that the subfamily Allodesminae are represented by two genera, Atopotarus and Allodesmus, and the latter genus is represented by at least six species; Al. kernensis, Al. sinanoensis, Al. naorai, Al. packardi, Al. demerei and Al. uraiporensis sp. nov. Allodesmus uraiporensis sp. nov. is one of the oldest and the northernmost record of the genus in the western North Pacific, and it suggests that the diversification of the genus in the western North Pacific was synchronous to the time of their diversification in the eastern North Pacific.

A new species of Pinnarctidion from the Pysht Formation of Washington State (U.S.A.) and a phylogenetic analysis of basal pan-pinnipeds (Eutheria, Carnivora)

“…7). This is consistent with recent suggestions that Pinnarctidion is excluded from crown Pinnipedia Tonomori et al, 2018;Paterson et al, 2020;Tate-Jones et al, 2020), but contradicts earlier suggestions that it is closely related to allodesmines (Barnes, 1979) or phocids (Berta, 1994a;Berta & Wyss, 1994). Pinnarctidion iverseni is more closely related to P. bishopi than either is to P. rayi.…”

A new tuskless walrus from the Miocene of Orange County, California, with comments on the diversity and taxonomy of odobenids

“…The recently described N. arandai ( Velez-Juarbe & Salinas-Márquez, 2018 ) may also be Serravallian, but its age is poorly constrained (15.7–9.2 Ma). The low number of odobenids is in contrast to the non-odobenid pinniped Allodesmus , which may have three to four described taxa in the Serravallian ( Boessenecker & Churchill, 2018 ; Tonomori et al, 2018 ). Boessenecker & Churchill (2018) suggest the possibility of competitive displacement of odobenids and Allodesmus , which seems plausible given their undeniable similarity in size, morphology, and presumably aspects of their ecology.…”

“…13D and 13E ), as in most odobenids and Allodesmus spp. ( Mitchell, 1966 ; Deméré, 1994b ; Tonomori et al, 2018 ). The posterior articular surface is convex and broad.…”

The coastal North Pacific: Origins and history of a dominant marine biota

“…Compsomyax (Amano, 1998), the Dosinia group (Amano & Hikida, 1999;Kurihara, 2006), Securella (Vermeij, 2001), borers Penitella (Kennedy, 1974) and Platyodon (Amano, 1998), and mussel Crenomytilus (Kafanov, 1987); the buccinid gastropod Lirabuccinum (Amano & Vermeij, 2003); the cancrid crabs Cancer and Metacarcinus (Schweitzer & Feldmann, 2000); barnacles of the genera Balanus, Semibalanus and the family Concavidae (Yamaguchi, 1987;Zullo, 1992;Zullo & Marincovich, 1990); surfperches of the family Embiotocidae (Longo & Bernardi, 2015); rockfishes of the genus Sebastes (Ingram, 2011); Pacific salmon of the genus Oncorhynchus (Crête-Lafrenière et al, 2012;Shedko et al, 2012); and the extinct seal genus Allodesmus (Tonomori, Sawamura, Sato, & Kohno, 2018).…”

“…Among participating clades are many familiar living and extinct shallow‐water lineages including muricid drillers of the genera Nucella and Ceratostoma (Amano & Vermeij, ; Amano, Vermeij, & Narita, ), at least three genera of naticid moon snails (Majima, ; Marincovich, ), the slipper limpet Grandicrepidula (Hoagland, ; Y. B. Gladenkov & Sinelnikova, ), grazing lottiid limpets (Nakano & Ozawa, ) and coiled snails of the genera Littorina (Reid, ), Chlorostoma (Hellberg, ) and Haliotis (Estes et al., ), and many shallow‐water bivalves such as Nuttallia (Amano & Ogihara, ), Epilucina (Kurihara, ), Rexithaerus (Matsubara, ), Compsomyax (Amano, ), the Dosinia group (Amano & Hikida, ; Kurihara, ), Securella (Vermeij, ), borers Penitella (Kennedy, ) and Platyodon (Amano, ), and mussel Crenomytilus (Kafanov, ); the buccinid gastropod Lirabuccinum (Amano & Vermeij, ); the cancrid crabs Cancer and Metacarcinus (Schweitzer & Feldmann, ); barnacles of the genera Balanus , Semibalanus and the family Concavidae (Yamaguchi, ; Zullo, ; Zullo & Marincovich, ); surfperches of the family Embiotocidae (Longo & Bernardi, ); rockfishes of the genus Sebastes (Ingram, ); Pacific salmon of the genus Oncorhynchus (Crête‐Lafrenière et al., ; Shedko et al., ); and the extinct seal genus Allodesmus (Tonomori, Sawamura, Sato, & Kohno, ).…”