Abstract:
A well-preserved skull from the early middle Miocene (approximately 15 Ma) at Devinska Nova Ves (formerly Neudorf an der
March), Slovakia, herein named Devinophoca claytoni, new genus
and new species, is morphologically the closest common ancestor
of all true seals. It shows a mixture of subfamilial characters. Features shared with Phocinae are the number of incisors and the lack
of a strongly pronounced mastoid process. Characters similar to
Monachinae are the shape of maxillae and the ratio between frontal and maxillary contacts of nasal bones. Characters shared with
Cystophorinae are the ratio between interorbital width and mastoid
width and (also shared with Phocinae) the ratio between length of
auditory bullae and distance between them. Moreover, this skull
has primitive features that are not known in any of the three subfamilies: Ml is triangular, with three cusps and three roots; in
P2-P4 the larger posterior roots are clearly made up of two fused
roots; the incisors form a curved line; the anterior palatal foramina
are deep and oval; and the sagittal crest is very well developed.
The traditional separation of the family Phocidae into the subfamilies Phocinae, Monachinae, and Cystophorinae has been
intensively debated during the past 40 years and debate continues
today, but we herein follow the traditional classification. The plesiomorphic D. claytoni is thus considered a sister taxon to the three
extant subfamilies of Phocidae and is referred to a new subfamily,
Devinophocinae. Because of its late age, D. claytoni cannot be
ancestral to the more advanced phocids. Its primitive characters in
combination with the characters it shares with the other subfamilies suggest, however, that it might approximate the common
ancestral morphotype.
