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| the early Pliocene site Langebaanweg, South Africa
in Valenciano & Govender, 2020.
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Abstract
Giant mustelids are a paraphyletic group of mustelids found in the Neogene of Eurasia, Africa and North America. Most are known largely from dental remains, with their postcranial skeleton mostly unknown. Here, we describe new craniodental and postcranial remains of the large lutrine Sivaonyx hendeyi and the leopard-size gulonine Plesiogulo aff. monspessulanus from the early Pliocene site Langebaanweg, South Africa. The new material of the endemic S. hendeyi, includes upper incisors and premolars, and fragmentary humerus, ulna and a complete astragalus. Its postcrania shares more traits with the living Aonyx capensis than the late Miocene Sivaonyx beyi from Chad. Sivaonyx hendeyi could therefore be tentatively interpreted as a relatively more aquatic taxon than the Chadian species, comparable to A. capensis. The new specimens of Plesiogulo comprise two edentulous maxillae, including one of a juvenile individual with incomplete decidual dentition, and a fragmentary forelimb of an adult individual. The new dental measurements point to this form being amongst the largest specimens of the genus. Both P3-4 differs from the very large species Plesiogulo botori from late Miocene of Kenya and Ethiopia. This confirms the existence of two distinct large species of Plesiogulo in Africa during the Mio/Pliocene, P. botori in the Late Miocene of Eastern Africa (6.1–5.5 Ma) and Plesiogulo aff. monspessulanus at the beginning of the Pliocene in southern Africa (5.2 Ma). Lastly, we report for the first time the presence of both Sivaonyx and Plesiogulo in MPPM and LQSM at Langebaanweg, suggesting that the differences observed from the locality may be produced by sedimentation or sampling biases instead of temporal replacement within the carnivoran guild.
Systematic Paleontology
Order Carnivora Bowdich, 1821
Suborder Caniformia Kretzoi, 1943
Family Mustelidae Fischer von Waldheim, 1817
Subfamily Lutrinae Bonaparte, 1838
Genus Sivaonyx Pilgrim, 1931
Type species: Sivaonyx bathygnathus (Lydekker, 1884) by original designation.
Other included species: S. africanus (Stromer, 1931); S. beyi; S. ekecaman Werdelin, 2003b; S. hendeyi; S. kamuhangirei Morales & Pickford, 2005; S. soriae Morales & Pickford, 2005 (=S. senutae Morales & Pickford, 2005 following Peigné et al., 2008); S. hessicus (Lydekker, 1890); Sivaonyx gandakasensis Pickford, 2007.
Remarks: Sivaonyx and Enhydriodon represent the largest African genera of bunodont otters, and their systematic position are debated (Morales & Pickford, 2005; Geraads et al., 2011; Grohé et al., 2013; Werdelin & Lewis, 2013, 2017; Werdelin, 2015; Ghaffar & Akhtar, 2016). Morales & Pickford, 2005 reassigned most of the African specimens with available dentition from Enhydriodon to Sivaonyx, a suggestion followed later by many authors (Pickford, 2007; Peigné et al., 2008; Lewis, 2008; Haile-Selassie, 2008; Haile-Selassie & Howell, 2009; Werdelin & Peigné, 2010; Grohé et al., 2013; Koufos, Mayda & Kaya, 2018), although recently new findings questioned this proposal (Geraads et al., 2011; Werdelin & Lewis, 2013; Werdelin, 2015). The aim of this work is not to resolve this controversy, and below we refer these taxa following the proposal of Morales & Pickford (2005). We also accept the presence of very large Enhydriodon in Africa with E. dikikae and Enhydriodon sp. from Woranso-Mille Area, Afar Region, Ethiopia, 3.6 Ma (Werdelin, Lewis & Haile-Selassie, 2014).
Sivaonyx hendeyi (Morales, Pickford & Soria, 2005)
Subfamily Guloninae Gray, 1825
Genus Plesiogulo Zdansky, 1924
Type species: Plesiogulo brachygnathus (Schlosser, 1903) by original designation.
Other included species: Plesiogulo marshalli (Martin, 1928); Plesiogulo monspessulanus Viret, 1939; Plesiogulo crassa Teilhard de Chardin, 1945; Plesiogulo praecocidens Kurtén, 1970; Plesiogulo lindsayi Harrison, 1981; Plesiogulo botori Haile-Selassie, Hlusko & Howell, 2004.
Plesiogulo aff. monpessulanus Viret, 1939
Locality: Langebaanweg, early Pliocene, LQSM and MPPM.
New material from Langebaanweg: SAM-PQL-40117, edentulous left maxillary of an adult specimen with P2-4 and M1 alveoli; SAM-PQL-47086, edentulous left maxillary of a juvenile specimen including a fragmented DP4 and alveoli for P3-M1 and DP3; SAM-PQL-6246, left distal part of a humerus; SAM-PQL-L3440, right distal part of a radius; C. SAM-PQL-6414, right proximal fragment of an ulna.
Alberto Valenciano and Romala Govender. 2020. New Insights Into the Giant Mustelids (Mammalia, Carnivora, Mustelidae) from Langebaanweg Fossil Site (West Coast Fossil Park, South Africa, early Pliocene). PeerJ. 8:e9221 DOI: 10.7717/peerj.9221
New insights into the giant mustelids from Langebaanweg fossil site: Author Interview with Alberto Valenciano
