PBDB Taxon

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Morphology	Ecology and taphonomy	External Literature Search	Age range and collections

Leptophoca

Mammalia - Carnivora - Phocidae

Taxonomy

Leptophoca was named by True (1906) [Sepkoski's age data: T Mi-m].

It was reranked as Monatherium (Leptophoca) by Friant (1947).

It was assigned to Monatherium by Friant (1947); to Phocinina by Koretsky (2001); to Carnivora by Sepkoski (2002); to Phocini by McKenna and Bell (1997), Koretsky and Barnes (2008); to Phocidae by Kellogg (1922), Zittel (1925), Carroll (1988), Hastings and Dooley (2017); and to Phocinae by True (1906), Hay (1930), Muizon (1981), Muizon (1982), Berta (2002), Koretsky and Holec (2002), Deméré et al. (2003), Berta (2009), Fulton and Strobeck (2010), Koretsky et al. (2012), Dewaele et al. (2017), Berta (2017), Berta et al. (2018), Kienle and Berta (2019), Hafed et al. (2023).

Species

L. proxima (syn. L. lenis)

Synonymy list

Year	Name and author
1906	Leptophoca True p. 836 figs. Plate LXXV
1922	Leptophoca Kellogg p. 122
1925	Leptophoca Zittel p. 78
1930	Leptophoca Hay p. 562
1947	Monatherium (Leptophoca) Friant p. 6
1981	Leptophoca Muizon p. 135
1982	Leptophoca Muizon p. 205 figs. Table 1
1988	Leptophoca Carroll
1997	Leptophoca McKenna and Bell p. 257
2001	Leptophoca Koretsky p. 86
2002	Leptophoca Berta p. 923
2002	Leptophoca Koretsky and Holec p. 175
2002	Leptophoca Sepkoski
2003	Leptophoca Deméré et al. p. 49 figs. Fig. 3.3
2008	Leptophoca Koretsky and Barnes p. 546
2009	Leptophoca Berta p. 863
2010	Leptophoca Fulton and Strobeck p. 817 figs. Figure 1
2012	Leptophoca Koretsky et al. p. 5
2017	Leptophoca Berta p. 157
2017	Leptophoca Dewaele et al. p. 10
2017	Leptophoca Hastings and Dooley p. 83
2018	Leptophoca Berta et al. p. 210 figs. Fig. 2
2019	Leptophoca Kienle and Berta
2023	Leptophoca Hafed et al.

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Rank	Name	Author
kingdom	Animalia	()
—	Bilateria
—	Eubilateria	Ax 1987
—	Deuterostomia
phylum	Chordata	Haeckel 1874
subphylum	Vertebrata
superclass	Gnathostomata
—	Osteichthyes	()
subclass	Sarcopterygii	()
subclass	Dipnotetrapodomorpha	(Nelson 2006)
subclass	Tetrapodomorpha	()
—	Tetrapoda
—	Reptiliomorpha
—	Anthracosauria
subclass	Amphibiosauria	Kuhn 1967
—	Cotylosauria	()
—	Amniota
subclass	Synapsida
—	Therapsida	()
infraorder	Cynodontia	()
—	Mammaliamorpha
—	Mammaliaformes
class	Mammalia

Rank	Name	Author
—	Cladotheria
—	Zatheria
subclass	Tribosphenida	()
subclass	Theria
—	Eutheria	()
—	Placentalia
—	Boreoeutheria
—	Laurasiatheria
—	Scrotifera
—	Ferae	()
—	Carnivoramorpha	Wyss and Flynn 1993
—	Carnivoraformes	Flynn et al.
order	Carnivora
suborder	Caniformia	Kretzoi 1943
infraorder	Canoidea	(Simpson 1931)
superfamily	Arctoidea	Flower 1869
—	Panpinnipedia	Wolsan et al. 2020
—	Pinnipedimorpha
—	Pinnipedia	()
family	Phocidae	()
subfamily	Phocinae
genus	Leptophoca

If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.

G. †Leptophoca True 1906

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†Leptophoca proxima Van Beneden 1876

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Invalid names: Leptophoca lenis True 1906 [synonym]

Diagnosis

Reference	Diagnosis
L. Dewaele et al. 2017	Large phocine, similar in size to large E. barbatus. The humerus of Leptophoca proxima differs from all other phocines in the following unique combination of characters: lesser tubercle of humerus small not reaching the proximal level of the humeral capitulum (also present in Praepusa vindobonensis, Prophoca rousseaui and S. sintsovi); intertubercular groove wide and shallow (also present in C. cristata, E. barbatus and Prophoca rousseaui); relatively straight posterior margin of the humeral capitulum; deltopectoral crest extending along the proximal two-third of humerus (also present in C. maeotica, Phoca vitulinoides, Prae. vindobonensis, Prophoca rousseaui and S. sintsovi); deltopectoral crest terminating abruptly, distally, but less abrupt than in extant Phocinae (also present in Prophoca rousseaui); deltopectoral crest mediolaterally thin; lateral epicondyle thin and strongly projecting posteriorly; deep and well-outlined coronoid fossa (also present in Phoca spp. and Pusa spp.) Koretsky (2001) presented a diagnosis of the cranium and mandible of Leptophoca proxima (as Leptophoca lenis). However, this diagnosis is based on isolated skulls and skull fragments and mandibles. Without any supported association to Leptophoca proxima, i.e., association with the humerus, the designation of any cranial or mandibular specimen to Leptophoca proxima remains doubtful. Therefore, we acknowledge the diagnosis by Koretsky (2001), but neither accept nor reject it. Similarly, Koretsky (2001) tentatively assigned a significant number of isolated postcranial bones to Leptophoca proxima. However, given the abundance of humeri from the Calvert Formation and other formations of the Chesapeake Group (Neogene of the mid-Atlantic coastal plain, Delaware, Maryland, North Carolina, and Virginia) assigned to Leptophoca proxima, it can relatively safely be assumed that other phocine bones that have been found in relatively large numbers in the Chesapeake Group, such as femora and tibiae, can be related to Leptophoca proxima as well. Nevertheless, no femora or tibiae from the Neogene of Belgium can be assigned to Leptophoca proxima. Hence, because the current study focuses on material from Belgium, neither the femur nor the tibia of Leptophoca proxima will be treated in detail here.