Unique Short-Faced Miocene Seal Discovered in Grytsiv (Ukraine)

S. Rahmat; I. Koretsky

S. Rahmat Howard University https://orcid.org/0000-0001-7410-8178
I. Koretsky Howard University

Keywords: Phocidae, Phocinae, Paratethys, Northern Black Sea Region

Abstract

Numerous Miocene fossil terrestrial mammals have been discovered at the Gritsev locality of Ukraine, but this is the first record of a fossil marine mammal found at this site. Dental morphology and morphometric analysis of the rostral portion of this middle-late Miocene (12.3-11.8 mya) partial skull suggests that it belongs to the subfamily Phocinae. The small size and cranial morphology of this partial skull is compared to Recent and fossil representatives of the extant subfamily Phocinae and the extinct subfamily Devinophocinae. Fossil and modern representatives of the extant subfamilies Cystophorinae and Monachinae were not incorporated in this study due to their extremely large size in comparison to this new finding. This newly described skull is a small-sized seal (likely similar in size to the modern sea otter based on the width of the rostrum) with an extremely short rostrum and several diagnostic characters that differ from all other fossil and extant phocines. Due to the lack of preservation and fragility of fossil seal skulls, less than 20 have been described so far. This new skull is yet another example of a small-sized ancestral seal, supporting the suggestion that modern seals have gotten larger over evolutionary history. Overall, any cranial information on fossil true seals is extremely vital to help resolve contentious phylogenetic relationships.

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