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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).
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
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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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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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. |
Measurements
No measurements are available
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| Source: f = family, p = phylum, uc = unranked clade | |||||
| References: Nowak 1991, Gingerich 2003, Carreño and Cronin 1993, Kiessling 2004 | |||||
Age range: base of the Burdigalian to the top of the Pliocene or 20.45000 to 2.58000 Ma
Collections (34 total)
| Time interval | Ma | Country or state | Original ID and collection number |
|---|---|---|---|
| Burdigalian | USA (Delaware) | L. lenis (18579) | |
| Burdigalian | Netherlands (Noord-Brabant) | L. amphiatlantica (123486) | |
| Langhian | USA (Virginia) | L. lenis (28368) | |
| Langhian | USA (Maryland) | L. lenis (18516 70818 71615 71809) L. sp., L. lenis (45506) L. sp., L. lenis, L. amphiatlantica (70823) | |
| Langhian - Serravallian | Belgium | Prophoca proxima (59123) | |
| Langhian - Serravallian | Belgium (Antwerpen) | Prophoca proxima (51680) | |
| Serravallian | USA (Virginia) | L. lenis (55690 57111 71798 71806 126605 187324) L. lenis, L. amphiatlantica (45508) Phocidae indet. (57700) | |
| Serravallian | USA (Maryland) | L. lenis (49945 70828 70836 70843 70854 88577 88578 88581 88582) L. sp., L. lenis (70835) | |
| Tortonian | Belgium (Antwerpen) | Prophoca proxima (52049 66960) | |
| Tortonian | USA (Maryland) | L. amphiatlantica (123487) | |
| Tortonian - Messinian | Belgium (Antwerpen) | Prophoca proxima (67022) | |
| Pliocene | USA (North Carolina) | L. lenis (123861) |