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A middle Miocene scene in Mae Moh, northern Thailand, illustrating five carnivorans:
in the right background Maemohcyon, and in the foreground, from right to left, Siamogale bounosa, Siamictis carbonensis, Viverra sp. and Leptoplesictis peignei.
Grohé, Bonis, Chaimanee, Chavasseau, Rugbumrung, ... et Jaeger. 2020.
Pencil drawing by Mélanie Grohé.
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Abstract
The late middle Miocene fossil-bearing lignite zones of the Mae Moh Basin, northern Thailand, have yielded a rich vertebrate fauna, including two species of Carnivora described thus far: the bunodont otter Siamogale thailandica (known from over a 100 specimens) and the large amphicyonid Maemohcyon potisati. Here we describe additional carnivoran material from Mae Moh comprising new remains of Maemohcyon potisati as well as remains of seven new carnivorans belonging to at least four families: a new species of Siamogale (S. bounosa), a new species of another otter (Vishnuonyx maemohensis), one representative of the genus Pseudarctos (a small amphicyonid), a new genus of Asian palm civet, Siamictis, one representative of another civet (cf. Viverra sp.), a new species of mongoose (Leptoplesictis peignei) and a Feliformia indet. This carnivoran assemblage constitutes one of the richest for the middle Miocene of eastern Asia and by far the richest for the Neogene of Southeast Asia. While the presence of new species indicates a certain degree of endemism for the Mae Moh Basin, paleobiogeographic cluster analyses conducted on carnivoran faunas from the middle and late Miocene of Asia indicates that a southern Asian biogeographic province, analogous to the current Oriental Realm, has existed since at least the middle Miocene. These results strengthen the observation that the Himalayan Mountains and Tibetan Plateau constitute significant physical barriers as well as an important climatic barrier (through the strengthening of monsoon systems) preventing north-south mammal dispersals in Asia since at least the middle Miocene.
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| FIGURE 1. Mae Moh Basin, northern Thailand. A, Location of the basin and view of the southwest pit where the most fossiliferous lignite zones Q and K are found. Photo by O.C.; B, Lithostratigraphic sequence of the basin with Carnivora-bearing zones and paleomagnetical dates from Benammi et al. (2002) and Coster et al. (2010). |
SYSTEMATIC PALAEONTOLOGY
Order Carnivora Bowdich, 1821
Suborder Caniformia Kretzoi, 1943
Superfamily Arctoidea Flower, 1869
Family Mustelidae Fischer, 1817
Subfamily Lutrinae Bonaparte, 1838
Siamogale Ginsburg et al., 1983
Type species: Siamogale thailandica Ginsburg et al., 1983.
Included species: Siamogale thailandica Ginsburg et al., 1983, S. melilutra Wang et al., 2018, S. bounosa, n. sp.
Siamogale bounosa, new species
Etymology: From Greek bounos (masculine), “hill”; for the bunodont teeth morphology
of this species.
Vishnuonyx Pilgrim, 1932
Type species: Vishnuonyx chinjiensis Pilgrim, 1932.
Included species: Vishnuonyx chinjiensis Pilgrim, 1932, V. angololensis Werdelin, 2003,
V. maemohensis, n. sp.
Vishnuonyx maemohensis, new species
Etymology: The species name derives from the locality where it was originally found,
Mae Moh.
Family Amphicyonidae Haeckel, 1866
Subfamily Amphicyoninae Haeckel, 1866
Maemohcyon Peigné et al., 2006
Maemohcyon potisati Peigné et al., 2006
Pseudarctos Schlosser, 1899
cf. Pseudarctos sp.
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FIGURE 9. A middle Miocene scene in Mae Moh, northern Thailand, illustrating five carnivorans: in the right background Maemohcyon, and in the foreground, from right to left, Siamogale bounosa, Siamictis carbonensis, Viverra, and Leptoplesictis peignei.
Pencil drawing by Mélanie Grohé.
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Suborder Feliformia Kretzoi, 1945
Family Viverridae Gray, 1821
Subfamily Paradoxurinae Gray, 1964
Siamictis carbonensis, new genus, new species
Etymology: Generic name derived from Siam, referring to Thailand, and ictis, meaning
“marten” in Greek. Species name derived from carbo, meaning “coal” in Latin, in reference to
the open coal mine of Mae Moh.
Subfamily Viverrinae Gray, 1964
cf. Viverra sp.
Family Herpestidae Gray, 1964
Leptoplesictis Major, 1903
Type species: Herpestes filholi Gaillard, 1899.
Other species included: L. aurelianensis (Schlosser, 1888), L. atavus Beaumont, 1973,
L. rangwai Schmidt-Kittler, 1987, L. mbitensis Schmidt-Kittler, 1987, L. senutae Morales et al.,
2008, L. namibiensis Morales et al., 2008, L. peignei, n. sp.
Leptoplesictis peignei, new species
Etymology: Species name in memory of Stéphane Peigné, who greatly contributed to
carnivoran systematics and evolution.
CONCLUSIONS:
Nine species of Carnivora are now recorded from the Mae Moh Basin. This fauna appears
endemic at the species level. It includes two semiaquatic mustelid genera: the piscivorous otter
Vishnuonyx and the bunodont otter Siamogale, represented by two species and the remains of
which are the most abundant among Mae Moh Carnivora. It is worth mentioning that Vishnuonyx maemohensis fossils provide the first undoubted record of the lower dentition of the genus
and is the most completely known species of this genus. In addition, four smaller feliforms are
also present at Mae Moh: two viverrids (including one new genus of Asian palm civet, Siamictis), one herpestid (Leptoplesictis, which represents the oldest Asian member of the family) and
a Feliformia indet. Amphicyonids are reported by a very small species (cf. Pseudarctos sp.) and
by the largest carnivoran mammal of the Mae Moh community (Maemohcyon potisati).
By conducting paleobiogeographical cluster analyses based on middle and late Miocene
carnivorans, we highlight the existence of a southern Asian biogeographic province, analogous
to the current Oriental Realm, since at the least the middle Miocene. This province results from
the physical barrier created by the Himayan Mountains and Tibetan Plateau as well as the climatic changes they generated through the strengthening of the monsoon systems in Asia.
Our study also demonstrates that carnivoran taxa can be used for the reconstruction of biogeographical provinces, and therefore should be integrated in future analyses.
Camille Grohé, Louis De Bonis, Yaowalak Chaimanee, Olivier Chavasseau, Mana Rugbumrung, Chotima Yamee, Kantapon Suraprasit, Corentin Gibert, Jérôme Surault, Cécile Blondel and Jean-Jacques Jaeger. 2020. The late Middle Miocene Mae Moh Basin of northern Thailand: the Richest Neogene Assemblage of Carnivora from Southeast Asia and A Paleobiogeographic Analysis of Miocene Asian Carnivorans.
American Museum Novitates. 3952: 1–57. DOI:
10.1206/3952.1 digitallibrary.amnh.org/handle/2246/7223
