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Leptophoca lenis

Osteichthyes - Carnivora - Phocidae

Taxonomy
Leptophoca lenis was named by True (1906). Its type specimen is USNM 5359, a limb element (humerus), and it is a 3D body fossil. Its type locality is Chesapeake Bay (Lower Calvert), which is in a Langhian marginal marine horizon in the Calvert Formation of Maryland.

It was recombined as Monatherium (Leptophoca) lenis by Friant (1947); it was synonymized subjectively with Leptophoca proxima by Dewaele et al. (2017).

Entered
by M. Uhen on 2006-03-14; modified by M. Uhen on 2018-01-02

Synonymy list
YearName and author
1906Leptophoca lenis True p. 836 figs. Plate LXXV
1922Leptophoca lenis Kellogg p. 123
1930Leptophoca lenis Hay p. 562
1947Monatherium (Leptophoca) lenis Friant p. 6
2001Leptophoca lenis Koretsky p. 62
2003Leptophoca lenis Deméré et al. p. 49 figs. Fig. 3.3
2008Leptophoca lenis Koretsky and Barnes p. 547
2012Leptophoca lenis Koretsky et al. p. 5
2023Leptophoca lenis Hafed et al.
2026Leptophoca lenis Dewaele p. 218

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RankNameAuthor
kingdomAnimalia()
—Bilateria
—EubilateriaAx 1987
—Deuterostomia
phylumChordataHaeckel 1874
subphylumVertebrata
superclassGnathostomata
classOsteichthyes
subclassSarcopterygii()
subclassDipnotetrapodomorpha(Nelson 2006)
subclassTetrapodomorpha()
—Tetrapoda
—Reptiliomorpha
—Anthracosauria
subclassAmphibiosauriaKuhn 1967
—Cotylosauria()
—Amniota
subclassSynapsida
—Therapsida()
infraorderCynodontia()
—Mammaliamorpha
—Mammaliaformes
classMammalia
—Cladotheria
RankNameAuthor
—Zatheria
subclassTribosphenida()
subclassTheria
—Eutheria()
—Placentalia
—Boreoeutheria
—Laurasiatheria
—Scrotifera
—Ferae()
—Pancarnivora
—CarnivoramorphaWyss and Flynn 1993
—CarnivoraformesFlynn et al.
orderCarnivora
suborderCaniformiaKretzoi 1943
infraorderCanoidea(Simpson 1931)
superfamilyArctoideaFlower 1869
—Panpinnipedia
—Pinnipedimorpha
—Pinnipedia()
familyPhocidae()
subfamilyPhocinae
genusLeptophoca
specieslenis

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.

†Leptophoca lenis True 1906
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Diagnosis
ReferenceDiagnosis
I. A. Koretsky et al. 2012Phocine of medium size. Greater trochanter of femur
higher than head, its proximal part wider than its distal; distinct lesser trochanter located far below distal border of greater trochanter; trochanteric fossa deep, wide, and overhang- ing medioproximally; head large in relation
to size of femur; minimum width of diaphysis situated proximally.
L. Dewaele 2026In the present study, an emended di-
agnosis from Dewaele et al. (2017b) is accepted. Medium-sized
phocine, comparable in size to the extant Phoca vitulina Linnaeus,
1758. The humerus of Leptophoca lenis differs from the humerus
of Leptophoca proxima in the following characteristics: overall
smaller size, stronger overall curvature, sigmoid shape of the di-
aphysis in lateral view (straighter in Leptophoca proxima); overall
bone morphology slightly laterally convex in proximal view, with
a slightly laterally convex deltopectoral crest in proximal view
(straighter in L. proxima); and more gradual distal termination
of the deltopectoral crest (more abrupt in L. proxima). Given the
incompleteness of the type specimens of L. lenis and L. proxima,
as well as the difficulty of quantifying the abovementioned differ-
ences, (e.g., the curvature of the diaphysis), Figure 3.5 puts both
type humeri side by side, providing visual cues for their separation.
Measurements
No measurements are available
Composition: hydroxyapatiteuc
Ontogeny: modification of partsuc
Environment: marineuc
Locomotion: actively mobilec
Life habit: amphibiousuc
Diet: piscivoref
Diet 2: carnivoref
Reproduction: viviparousuc
Created: 2005-06-08 10:11:09
Modified: 2005-06-08 12:11:09
Source: f = family, c = class, uc = unranked clade
References: Gingerich 2003, Nowak 1991, Carreño and Cronin 1993, Hendy et al. 2009

Age range: base of the Burdigalian to the top of the Pliocene or 20.45000 to 2.58000 Ma

Collections (26 total)


Time interval Ma Country or state Original ID and collection number
Burdigalian20.45 - 15.98USA (Delaware) Leptophoca lenis (18579)
Langhian15.98 - 13.82USA (Virginia) Leptophoca lenis (28368)
Langhian15.98 - 13.82USA (Maryland) Leptophoca lenis (type locality: 18516 45506 70818 70823 71615 71809)
Serravallian13.82 - 11.63USA (Maryland) Leptophoca lenis (49945 70828 70835 70836 70843 70854 88577 88578 88581 88582)
Serravallian13.82 - 11.63USA (Virginia) Leptophoca lenis (45508 55690 57111 71798 71806 126605 187324)
Pliocene5.333 - 2.58USA (North Carolina) Leptophoca lenis (123861)