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I. Koretsky, S. Rahmat and N. Peters

Abstract

Rare Late Miocene Seal Taxa (Carnivora, Phocidae) from the North Sea Basin. Koretsky, I., Rahmat, S., Peters, N. - Th e discovery of new late Miocene fossil true seals from the North Sea Basin in Northern Europe provides important information regarding the radiation of monachines and phocines in the Eastern Atlantic. Examination of the first fossil seal remains from the Gram Formation, western Denmark, allowed redescriptions and emended diagnoses of several taxa. Analysis of diagnostic material recovered from western Denmark and Th e Netherlands shows the presence of at least three phocid genera and reveals new information on the taxonomic variability of true seals. Due to the close relationships that exist between these phocid faunas, a correlation was demonstrated between different localities of Northern and Western Europe and provides the opportunity to associate localities of the Western and Central Paratethys with the eastern and western shores of the North Atlantic. Morphological analyses of postcranial material identifi ed three new late Miocene species (Pontophoca jutlandica, Subfamily Monachinae; Gryphoca nordica and Platyphoca danica, both Subfamily Phocinae), suggesting that the maximum evolutionary diversity of mid-Tertiary phocids occurred first in the Paratethys and later in the North Atlantic Basins.

Open access

I.A. Koretsky, S.J. Rahmat and N. Peters

Abstract

Remarks on Correlations and Implications of the Mandibular Structure and Diet in Some Seals (Mammalia, Phocidae). Koretsky, I. A., Rahmat, S. J., Peters, N. — The diverse representatives of Recent seals within the three extant subfamilies (Cystophorinae, Phocinae, Monachinae) of the family Phocidae exhibit dietary variations among species, feeding on invertebrates and a diversity of prey depending on the season and availability. To explain this variability, an introductory morphological examination of the mandibular structure of Recent seals from each subfamily was performed, focusing on: heights of the mandibular ramus and condyloid process; measurements of the masseteric fossa; and attachments of muscles of mastication. After measuring the condyloid angles (the inclination of the condyloid process in relation to the axis of the alveolar row) among the examined species, a correlation between the size ofthe angle, function, and diet was recognized. Seals with a tall mandibular ramus and greater condyloid angle (Cystophorinae) feed on larger-sized prey, while seals with a shorter ramus and lesser condyloid angle feed on small (Monachinae) to medium-sized (Phocinae) prey, regardless of the overall size of the seal. This study focused on the mandibular morphology of some living and fossil representatives of Phocidae, providing an association between functional and ecological interpretations of modern seals in general and extrapolating this knowledge for fossil dietary preference.