Phocinae Gray 1821

Subfamily PHOCINAE

Due to the lack of preservation and fragility of fossil seal skulls, less than 20 specimens have been described so far, with only a few belonging to representatives of the subfamily Phocinae. This new partial seal skull of Planopusa semenovi is extremely small and has a short face (based on the size of the rostral part and teeth). Based on teeth formula, Pl. semenovi sp. n. belongs to the subfamily Phocinae and will be compared to other recent and fossil phocine seals.

Planopusa semenovi differs from:

Recent Pusa capsica by: being smaller, having well-developed, round anterior palatal foramen; the presence of palatal groove; the absence of diastema; the shape of the proximal edge of hard palate.

Phocanella sp., cf. P. pumila (Pliocene, Yorktown Formation 5.3–3.6 Ma) from Lee Creek Mine, USA (Ray et al., 2008) by: the lack of diastema between teeth; short concavity over P 1 in preorbital part of the maxilla; the flattened palatal process of maxilla; the reverse ratios between P4 and M1; wider rostrum; rounded anterior palatal foramen, and deeper palatal groove.

Histriophoca alekseevi (Middle Miocene, middle Sarmatian [~11.6–9.9 Ma] of the Eastern Paratethys) by: the absence of diastemata; the flattened palatal process of the maxilla; the reverse ratios between P4 and M1; wider rostrum; round and deep anterior palatal foramen; uneven depth of the palatal groove.

Monachopsis pontica (Middle Miocene, middle Sarmatian [~11.6–9.9 Ma] of the Eastern Paratethys) by: the smaller width of the palatal process; narrowest infraorbital foramen of any known fossil or modern seal, but larger than in other seals from the same region (such as Histriophoca alekseevi, and Praepusa vindobonensis); longer and narrower teeth; width of the rostrum part of the skull (table 1; which is similar in size to Leptophoca lenis despite the smaller size, but wider than in Histriophoca alekseevi).

Prepusa vindobonensis (middle Miocene, early Sarmatian [~12.8–11.6 Ma] of the Central and Eastern Paratethys) by: upper incisors forming a straight line; the absence of diastemata; the short concavity over P 1 in preorbital part of the maxilla; rounded anterior palatal foramen; the similar width of rostrum (despite overall smaller size).

Leptophoca lenis (Early Miocene [~16 Ma], USA) by: upper incisors forming a straight line; the absence of diastema; short concavity over P1 of the preorbital part of the maxilla; rounded anterior palatal foramen; similar width of the rostrum (despite overall smaller size).