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Zygolophodon

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Zygolophodon
Temporal range: Early Miocene–Late Miocene
Skull of Zygolophodon sp. from Laogou, Gansu Province, China
Molars of Zygolophodon turicensis
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Proboscidea
Family: †Mammutidae
Genus: †Zygolophodon
Vacek, 1877
Type species
†Zygolophodon turicensis
Vacek, 1877
Species
  • Z. aegyptensis Sanders & Miller, 2002
  • Z. atavus Borissiak, 1936
  • Z. gobiensis Osborn & Granger, 1932
  • Z. metachinjiensis Osborn, 1929
  • Z. proavus Cope, 1873
  • Z. turicensis Schintz, 1824

Possibly valid species:

  • Z. chinjiensis Chow & Chang, 1978
  • Z. lufengensis Zhang, 1982
  • Z. nemonguensis Chow & Chang, 1961
Synonyms
List
  • Mastodon proavus Cope, 1873
  • Mastodon tapiroides Cuvier, 1824
  • Mastodon turicensis Schnitz, 1824
  • Mammut tapiroides Cuvier, 1824
  • Mammut turicensis Schnitz, 1824

Zygolophodon is an extinct genus of mammutid proboscidean that lived during the Miocene in Africa, Eurasia, and North America.[1]

Description

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As with other mammutids, the molars have a zygodont morphology. The lower jaw has an elongate mandibular symphysis and bears tusks/incisors.[2][3] The upper tusks have enamel bands and are untwisted and downward curving, and outwardly diverge from each other.[4] The jaws retained permanent premolar teeth.[5]

Ecology

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Zygolophodon is suggested to have primarily had a browsing-based diet.[6]

Taxonomy

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Zygolophodon belongs in the family Mammutidae, whose best known member is the American mastodon (Mammut americanum).

The genus likely originated in Africa. The oldest species is Z. aegyptensis, known from Egypt and Namibia, dating to the late Early Miocene-early Middle Miocene.[7][8] The species Z. turicensis had a widespread distribution in both Africa (Kenya, Tunisia), Anatolia and Europe, dating to the Early-Late Miocene,[9][8] with its earliest appearance in Europe being approximately 18-17 million years ago,[10] and last appearance in the region dating to around 7-6 million years ago.[11] The youngest confirmed record of Zygolophodon in Africa dates to around 13 million years ago, based on teeth suggested to belong to Z. turicensis found in Kenya, though a possible younger record is known from the Late Miocene of Algeria.[12]

The species Z. tapiroides (Desmarets, 1822) is considered invalid.[8][13] The taxonomy of East Asian Zygolophodon is uncertain. Tassy et al. (1988) synonymised many Chinese species with Z. gobiensis (including Z. lufengensis, Z. chinjiensis, Z. nemonguensis, Z. gromovae and Z. jiningensis, as well as Miomastodon tongxiensis), with Z. gobiensis also known from Mongolia, but other authors suggest that at least some of these species may be valid.[8] The species Z. atavus is known from the early Middle Miocene of Kazakhstan.[8] The oldest remains of Zygolophodon on the Indian subcontinent are known from the Bugti Hills of Pakistan, dating to around 19-17 million years ago. The species Z. metachinjiensis is known from the mid-Late Miocene of Pakistan.[14] Zygolophodon has also been reported from western India, dating to the mid Miocene,[15] and other probable remains dating to the Late Miocene, around 10 million years old, representing the youngest mammutids on the Indian subcontinent.[14] An indeterminate species has also been reported from Thailand, of uncertain but probably Late Miocene age.[8]

Zygolophodon entered North America during the latter part of the Early Miocene (during the late Hemingfordian faunal stage), with the oldest record being a partial tooth from Massacre Lake, Nevada, dating to 16.5-16.4 million years ago.[3] Remains of Zygolophodon are known from across western and central North America during the following Barstovian (including Colorado, California, Montana, Oregon, Nebraska, Nevada, Wyoming and Saskatchewan). Z. proavus currently represents the only known North American species of Zygolophodon.[13][3] The youngest specimens of Z. proavus date to approximately 11-12 million years ago.[3] Mammut is thought to be descended from Zygolophodon. The species "Mammut" borsoni, whose relationship with North American Mammut is controversial, and sometimes placed in Zygolophodon (from which, like North American Mammut, it descended from), is the youngest member of Mammutidae in Eurasia, persisting from the Late Miocene into the Earliest Pleistocene, around 2.5-2 million years ago.[10]

Some authors have suggested placing M. tongxinensis, Z. gobiensis and Z. metachinjiensis within a revived Miomastodon, which was originally described for the North American Miomastodon merriami.[16] Miomastodon is usually treated as a synonym of Zygolophodon (with M. merriami typically considered a synonym of Z. proavus)[13] and other authors have reacted with caution to the proposal.[10]

References

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  1. ^ Youping, Yuzhu, Hongxiang, Suyin, Zhang, Long, Ji, Ding (November 1999) [March 1989]. "The Cenozoic Deposits of the Yunnnan Region (Institute of Vertebrate Paleontology, Paleoanthropology Academia Sinica)" (PDF). Professional Papers on Stratigraphy and Paleontology, No. 7 Geological Publishing House, Peking, China, Pp. 1-21.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  2. ^ Mothé, Dimila; Avilla, Leonardo S.; Zhao, Desi; Xie, Guangpu; Sun, Boyang; Mothé, Dimila; Avilla, Leonardo S.; Zhao, Desi; Xie, Guangpu (2016). "A new Mammutidae (Proboscidea, Mammalia) from the Late Miocene of Gansu Province, China". Anais da Academia Brasileira de Ciências. 88 (1): 65–74. doi:10.1590/0001-3765201520150261. ISSN 0001-3765. PMID 26839998.
  3. ^ a b c d Koenigswald, Widga & Göhlich (2021): New mammutids (Proboscidea) from the Clarendonian and Hemphillian of Oregon – a survey of Mio-Pliocene mammutids from North America
  4. ^ Yaghoubi, Sadaf; Ashouri, Ali Reza; Ataabadi, Majid Mirzaie; Ghaderi, Abbas (2023-07-05). First true mastodon from the Late Miocene of Western Asia (Report). In Review. doi:10.21203/rs.3.rs-3046011/v1.
  5. ^ Sanders, William J. (2018-02-17). "Horizontal tooth displacement and premolar occurrence in elephants and other elephantiform proboscideans". Historical Biology. 30 (1–2): 137–156. Bibcode:2018HBio...30..137S. doi:10.1080/08912963.2017.1297436. ISSN 0891-2963. S2CID 89904463.
  6. ^ Janis, C (May 2004). "The species richness of Miocene browsers, and implications for habitat type and primary productivity in the North American grassland biome". Palaeogeography, Palaeoclimatology, Palaeoecology. 207 (3–4): 371–398. Bibcode:2004PPP...207..371J. doi:10.1016/j.palaeo.2003.09.032.
  7. ^ W. J. Sanders and E. R. Miller. 2002. New proboscideans from the early Miocene of Wadi Mogahara, Egypt. Journal of Vertebrate Paleontology 22(2):388-404
  8. ^ a b c d e f Duangkrayom, J., Wang, S., Deng, T., & Jintasakul, P. (2017). The first Neogene record of Zygolophodon (Mammalia, Proboscidea) in Thailand: Implications for the mammutid evolution and dispersal in Southeast Asia. Journal of Paleontology, 91(1), 179-193. doi:10.1017/jpa.2016.143
  9. ^ Erten, Hüseyin; Koralay, Demet Banu (December 2020). "A Zygolophodon turicensis (Proboscidea, Mammalia) mandible fragment from the Kale-Tavas basin (Denizli, Turkey)". Palaeobiodiversity and Palaeoenvironments. 100 (4): 1077–1082. Bibcode:2020PdPe..100.1077E. doi:10.1007/s12549-020-00422-7. ISSN 1867-1594. S2CID 215741701.
  10. ^ a b c Koenigswald, Wighart; Březina, Jakub; Werneburg, Ralf; Göhlich, Ursula (2022). "A partial skeleton of "Mammut" borsoni (Proboscidea, Mammalia) from the Pliocene of Kaltensundheim (Germany)". Palaeontologia Electronica. 25 (1): 1–45. doi:10.26879/1188. S2CID 247374131.
  11. ^ Mazo, A.V.; Van der Made, J. (March 2012). "Iberian mastodonts: Geographic and stratigraphic distribution". Quaternary International. 255: 239–256. Bibcode:2012QuInt.255..239M. doi:10.1016/j.quaint.2011.07.047.
  12. ^ Pickford, M. 2007. New mammutid proboscidean teeth from the middle Miocene of tropical and southern Africa. Palaeontologia Africana 42: 29–35.
  13. ^ a b c Lofgren, Don L.; Anand, Rajsavi S. (November 2011). "Partial skull of Zygolophodon (Mammalia, Proboscidea) from the Barstow Formation of California". Journal of Vertebrate Paleontology. 31 (6): 1392–1396. Bibcode:2011JVPal..31.1392L. doi:10.1080/02724634.2011.605192. ISSN 0272-4634. S2CID 86845027.
  14. ^ a b Choudhary, Deepak; Jukar, Advait M.; Patnaik, Rajeev; Singh, Nongmaithem Amardas; Singh, Ningthoujam Premjit; Milankumar Sharma, K. (2022-10-28). "The first report of cf. Zygolophodon (Mammalia, Proboscidea, Mammutidae) from the Upper Miocene of Kutch, India". Journal of Vertebrate Paleontology. 42 (4). Bibcode:2022JVPal..42E7959C. doi:10.1080/02724634.2023.2197959. ISSN 0272-4634. S2CID 258338571.
  15. ^ Kapur, Vivesh V; Pickford, Martin; Chauhan, Gaurav; Thakkar, M.G. (2021-05-04). "A Middle Miocene (~14 Ma) vertebrate assemblage from Palasava, Rapar Taluka, Kutch (Kachchh) District, Gujarat State, western India". Historical Biology. 33 (5): 595–615. Bibcode:2021HBio...33..595K. doi:10.1080/08912963.2019.1648451. ISSN 0891-2963. S2CID 202008961.
  16. ^ Wang, S.-Q., Zhang, X.-X., and Li, C.-Y. 2020. Reappraisal of Serridentinus gobiensis Osborn and Granger and Miomastodon tongxinensis Chen: The Validity of Miomastodon. Vertebrate PalAsiatica, 58:134-158.
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