Asiadidelphis akbarbugtii, Crochet & Antoine & Benammi & Iqbal & Marivaux & Métais & Welcomme, 2007
|
publication ID |
https://doi.org/ 10.5517/ccnnv9f |
|
persistent identifier |
https://treatment.plazi.org/id/03D34300-0658-FFA9-D661-FCE2DB96F985 |
|
treatment provided by |
Felipe |
|
scientific name |
Asiadidelphis akbarbugtii |
| status |
sp. nov. |
Asiadidelphis akbarbugtii sp. nov.
Figs. 2 View Fig , 3 View Fig .
Holotype: PMNH−DBC2−2180 , a left M2 ( Figs. 2A View Fig , 3B View Fig ).
Referred material: PMNH−DBC2−2179 ( Figs. 2B View Fig , 3A View Fig ), a left M2; PMNH−DBC2−2223 ( Fig. 2C View Fig ), a right M4.
Type locality: Paali Nala−DBC2, Bugti Hills, Balochistan, Pakistan (Welcomme et al. 2001).
Formation and age: Chitarwata Formation;Bugti Member, Early Oligocene (Welcomme et al. 2001).
Etymology: The name is dedicaced to Nawab Akbar Shahbaz Khan Bugti, tribal chief of the Bugti People, leader of the Jamhoori Watan Party, recently deceased; in recognition of his great interest in our paleontological investigations and his kind hospitality during all the French field expeditions in the Bugti territory.
Differential diagnosis.— Asiadidelphis akbarbugtii differs from A. zaissanense and A. tjutkovae in its larger size, and in having the lingual border of upper molars more rounded, more massive cusps, more developed conules, larger stylar cusp C on M2, and from A. zaissanense in showing a distinct anterior cingulum. Moreover, the upper molars of A. akbarbugtii are also characterized by a lesser development of the didelphidian dilambdodonty.
Description.—PMNH−DBC2−2179 (length = 2.84 mm, width = 3.85) and PMNH−DBC2−1980 (length = 2.84 mm, width = 3.68) are two left M2; the first one appears slightly weathered, but the wearing surfaces are still clearly visible ( Fig. 3 View Fig ). The labial bor− der is weakly concave. Stylar cusps A and B are strongly worn, so that a single wearing surface is preserved ( Fig. 3A, B View Fig ). The cusp C is strong and high in regard to its limited wearing surface. The cusp D is not visible, but such an absence is frequent in the Herpetotheriidae ( Crochet 1980a) . The cusp E is the lowest cusp, and it is located on the labial end of the metacrista. The preprotocrista joins the stylar cusp A. The paracone is slightly shifted labially with respect to the metacone. The centrocrista does not reach the stylar line, which corresponds to strict didelphidian dilambdodonty as defined by Crochet (1980: 28). The large development of the conules can be deduced from the large size of the corresponding wear surfaces. The lingual margin of the crown surrounding the protocone is noticeably rounded, suggesting that these teeth are both M2.
UMC−DBC2−2223 ( Fig. 3C View Fig ) is a right M4 (length = 1.84 mm; width = 3.12 mm). The anterior styles and the stylar cusp A are freshly broken. According to the size of its partly preserved labial base, the stylar cusp B was probably high. The small cusp located just posterior to the cusp B can be identified as either the cusp D or a duplication of the cusp C, as observed in Amphiperatherium (Crochet 1980) . The cusp C is high and it displays a distinct horizontal wearing surface. Because of the labial position of the paracone, the reduced metacentrocrista is not linked to the cusp C. Conules are well developed. The paracingulum extends labially along the preserved part of the paracone.
Discussion
Despite slight variations in morphology and size, all the specimens from Paali described here are referred to Asiadidelphis akbarbugtii sp. nov. The relative size of stylar cusps, their position on the labial margin of the molar (especially on PMNH−DBC2−2179 and PMNH−DBC2−2180), the didelphidian dilambdodonty, the lingual position of the paracone, and the lack of hypocone are all suggestive of close affinities with didelphimorph marsupials (order Didelphimorphia Gill, 1872 ). Moreover, within Didelphimorphia , characters like the slenderness of the principal cusps, and the absence of a lingual cingulum undoubtedly indicate that these teeth belong to a member of the Herpetotheriidae Trouessart, 1879 . The attrition surfaces extending along the lingual sides of the paracone and metacone are not interpretable in term of microwear pattern as teeth seemingly underwent post−mortem polishing resulting from a probable phase of fluvial transport. However, microwear, located on the apices of the cusps suggests the prominence of abrasion chewing processes during occlusion ( Crochet 1980b).
The current picture yielded by the poor fossil record of Cenozoic marsupials suggests that the peradectids were widely distributed in the Old World, since they are reported from the early Eocene of Tunisia (Chambi) with Kasserinotherium tunisiense ( Crochet 1986; Hartenberger et al. 2001), and from both the early Oligocene of Egypt (Gebel El Qatrani, Fayum) and the Arabic peninsula (Taqah, Sultanate of Oman) with Qatranitherium africanum (Simons and Bown 1984; Crochet et al. 1992). The peradectids are also known in the early Miocene of China (Songlinzhuang) with Sinoperadectes clandestinus (Storch and Qiu 2002) and from the middle Miocene of Thailand (Mae Long and Li Basins) with Siamoperadectes minutus ( Ducrocq et al. 1992; Mein and Ginsburg 1997). The few specimens of marsupials reported from the Eocene of Turkey and referred to the Herpetotheriinae ( Kappelman et al. 1996), and to “? Marsupialia , gen. and sp. indet.” (Maas et al. 1998) display an unusual and highly specialized dental morphology within the Marsupialia , and their affinities remain unresolved so far.
In contrast, the herpetotheriids (order Didelphimorphia ) seem to have been geographically restricted to the north side of the Tethys Sea. Asiadidelphis zaissanense is known from the late Eocene ( Gabunia et al. 1990) and Asiadidelphis tjutkovae from the early Oligocene ( Emry et al. 1995) of the Zaysan Basin, Eastern Kazakhstan. Qi et al. (1996) reported the occurrence in China of an “ Asiadidelphis −like opossum ( Didelphidae )” from the middle Eocene fissure fillings of Shanghuang (Jiangsu Province), but the specimen are yet to be described in detail. Recently, Bajpai et al. (2005) reported two new genera from the early Eocene of India, both based on lower molars ( Indodelphis and Jaegeria ). According to the oblique orientation of the wear surfaces in Indodelphis , it is unlikely referable to the Peradectidae , in which these surfaces are invariably horizontal ( Crochet 1980a). Indodelphis is probably rather referable to the Herpetotheriidae like Asiadidelphis , but further comparisons with the later genus are precluded as all the species of Asiadidelphis are based only on upper molars. At this point however, we cannot exclude that Indodelphis is actually a junior synonym of Asiadidelphis . The genus Jaegeria was reported by Bajpai et al. (2005) from the same locality and tentatively referred to “ Didelphidae Herpetotheriinae”. Again, the lower molars of Jaegeria prevent extensive comparisons with other Asian taxa, but both their morphology and size are reminiscent of the “ Didelphidae Herpetotheriinae gen. et sp. indet.” from the Ganda Kas area (Kuldana Formation) of northern Pakistan (Thewissen et al. 2001). However, we express some doubt on the real marsupial affinities of Jaegeria and “ Didelphidae Herpetotheriinae gen. et sp. indet.” because of several dental features including the pinched trigonid, the height of the prefossid in lingual view, and the somewhat medial position of the hypoconulid on the lower molars. Further material is necessary to test the systematic affinities of these enigmatic Asian taxa.
It clearly appears from this short overview of the Cenozoic fossil record of Asian marsupials that the upper teeth from Kazakhstan referred to Asiadidelphis ( Gabunia et al. 1984, 1990; Emry et al. 1995) provide the most relevant comparisons for the new specimens from Paali. The genus Asiadidelphis is based on the species A. zaissanense , which is only documented by upper molars ( Gabunia et al. 1990). However, because of the scarcity of the available material, we think that the diagnoses based on dental characters are not consistent enough to differentiate Asiadidelphis from the other genera belonging to the Herpetotheriidae . A. tjutkovae reported by Emry et al. (1995) does not provide additional morphological data for the genus since this species is mainly based on its size (25 to 30% larger than A. zaissanense ). The well−preserved and complete upper molars from Paali possess most of the characters mentioned by Gabunia et al. (1990), including the connection between the preprotocrista and the stylar cusp A ( Fig. 2A 2 View Fig ). It is worth noting that this dental feature and the prominence of the stylar cusp C are also observable in Amphiperatherium minutum , a didelphimorph marsupial from the Paleogene of Europe ( Crochet 1980a: 84).
Conclusion
The specimens from the Paali locality in Bugti Hills exhibit diagnostic characters of the genus Asiadidelphis , but their autapomorphies and larger size justify the recognition of a new species. The occurrence of A. akbarbugtii in Central Pakistan confirms the wide distribution of marsupials in Asia during the Paleogene. Although the fossil record of Paleogene marsupials in Asia remains poorly documented, the data have so far suggested that the herpetotheriids were mainly distributed north of the Alpine−Himalayan complex. In contrast, the peradectids may have been restricted to southern Asia with the exception of Sinoperadectes from the early Miocene of the Jiangsu Province, eastern China. The rise of the Himalayan Chain certainly constituted a physical barrier and it probably induced climatic changes that favored faunal provincialism in Asian during the middle and late Cenozoic. However, the presence of an undisputable Oligocene herpetotheriid in the southern Himalaya indicates that faunal exchanges also occurred between the Asian mainland and the Indian subcontinent as suggested by other groups of mammals ( Clyde et al. 2003).
Acknowledgments.—We are grateful to the late Nawab Akbar Shahbaz Kan Bugti, Lord of the Bugti Tribes, for his continuous support and interest in our researches; Brahumdagh Khan Bugti, Shaheed Hassan Bugti, for their invitations and useful help. We are indebted to Kamal Madjidulab (Karachi, Pakistan) for his enthusiastic help and Marc de Grossouvre, former “Attaché de coopération scientifique et universitaire” (French Embassy, Islamabad, Pakistan) for his support. Drawings are due to Laurence Meslin (ISEM−Montpellier, France). Fieldworks in Pakistan were funded by the program CNRS−ECLIPSE and the Ministry of Foreign Affairs (MAE, French Embassy, Islamabad). We thank Lawrence J. Flynn (Peabody Museum, Harvard University, Cambridge, USA) and Robertand Robert J. Emry (Smithsonian Institution, National Museum of Natural History, Washington, D.C., USA) who reviewed this paper and provided very useful comments. This is publication of the “Institut des Sciences de l'Evolution de Montpellier” UMR−CNRS 5554, n ° 2006 −023, and the “ Mission Paléontologique Française au Balouchistan ” n ° 34.
References
Antoine, P.−O., Ducrocq, S., Marivaux, L., Chaimanee, Y., Crochet, J.−Y., Jaeger, J.−J., and Welcomme, J.−L. 2003. Early rhinocerotids (Mammalia, Perissodactyla) from South Asia. Canadian Journal of Earth Science 40: 365–374.
Antoine, P.O., Shah, S.M.I., Cheenna, I.U., Crochet, J.−Y., de Francheschi, D., Marivaux, L., Métais, G. and Welcomme, J.−L. 2004. News remains of the baluchithere Paraceratherium bugtiense (Pilgrim, 1910) from the Late / latest Oligocene of the Bugti hills, Balochistan, Pakistan. Journal of Asian Earth Science 14: 71–77.
Bajpai, S., Kapur V.V., Thewissen J.G.M., Tiwari B.N., and Das, D.P. 2005. First fossil marsupials from India: early Eocene Indodelphis n. gen. and Jaegeria n. gen. from Vastan lignite mine, District Surat, Gujarat. Journal of the Palaeontological Society of India 50: 147–51.
Clemens, W.A. 1966. Fossil Mammals of the Lance Formation, Wyoming. Part II, Marsupialia. University of California. Publications in Geological Sciences 62: 1–122.
Clyde, W.C., Khan, I.H., and Gingerich, P.D. 2003. Stratigraphic response and mammalian dispersal during initial India−Asia collision:Evidence from the Ghazij Formation, Balochistan, Pakistan. Geology 31: 1097–100.
Crochet, J.−Y. 1980 a. Les marsupiaux du Tertiaire d’Europe. 279 pp. Editions de la Fondation Singer−Polignac, Paris.
Crochet, J.−Y. 1980 b. L’occlusion dentaire chez Peradectes, Amphiperatherium et Peratherium, marsupiaux du Tertiaire d’Europe. Palaeovertebrata, Mémoire Jubilaire en hommage a René Lavocat: 79–89.
Crochet, J.−Y. 1986. Kasserinotherium tunisiense nov. gen, nov. sp., troisième marsupial découvert en Afrique (Eocène inférieur de Tunisie). Comptes Rendus de l’Académie des Sciences de Paris, série IIa 302: 923–926.
Crochet, J.−Y., Thomas, H., Sen, S., Roger, J., Gheerbrant, E., and Al−Sulaimani, Z. 1992. Découverte d’un Péradectidé (Marsupialia) dans l’Oligocène inférieur du Sultanat d’Oman: nouvelles données sur la paléobiogéographie des marsupiaux de la plaque arabo−africaine. Comptes Rendus de l’Académie des Sciences de Paris, série IIa 314: 539–545.
Ducrocq, S., Buffetaut, E., Buffetaut−Tong, H., Jaeger, J.−J., Jongkanjanasoontorn, Y., and Suteethorn, V. 1992. First fossil marsupial from South Asia. Journal of Vertebrate Paleontology 12: 395–399.
Emry, R.I., Lucas, S.G., Szalay, F.S., and Tleuberdina, P.A. 1995. A new herpetotheriine didelphid (Marsupialia) from the Oligocene of central Asia. Journal of Vertebrate Paleontology 15: 850–854.
Forster−Cooper, M.A. 1924. The Anthracotheriidae of the Dera Bugti deposits in Baluchistan. Memoirs of the Geological Survey of India 4: 1–59.
Gabunia, L.R., Shevyreva, N.S., and Gabunia, V.D. 1984. On the presence of fossil marsupials in Asia [in Georgian]. Bulletin of Academy of Sciences of the Georgian SSR 116: 169–171.
Gabunia, L.R., Shevyreva, N.S., and Gabunia, V.D. 1990. A new oposssum (Didelphidae, Marsupialia, Metatheria, Mammalia) from the lowermost Oligocene in the Zaysan Basin (Eastern Kazakhstan) [in Russian]. Paleontologičeskij žurnal 1: 101–109.
Gheerbrant, E. 1991. Tylus (Eutheria, Adapisoriculidae) and the absence of ascertained marsupials in the Paleocene of Europe. Terra Nova 3: 586–592.
Hartenberger, J.−L., Crochet, J. −Y, Martinez, C., Marandat, B., and Sigé, B. 2001. The Eocene Mammalian Fauna of Chambi (Tunisia) in its Geological Context. In: G.F.Gunnell (ed.), Unusual Occurrences and Rarely Sampled Habitats, 237–250. Kluwer Acad./Plenum Publishers, New York.
Kappelman, J., Mass, M.C., Sen, S., Alpagut, B., and Lunkka, J.−P. 1996. A new Tertiary mammalian fauna from Turkey and its paleobiogeographic significance. Journal of Vertebrate Paleontology 16: 592–595.
Lydekker, R. 1884. Additional Siwalik Perissodactyla and Proboscidea. Memoirs of the Geological Survey of India—Palaeontologica Indica, Series 10 3: 1–34.
Lindsay, E.H., Flynn, L.J., Cheema, I.U., Barry, J.C., Downing, K.F., Rajpar, A.R., and Raza, S.M. 2005. Will Downs and the Zinda Pir Dome. Palaeontologia Electronica 8: 1–19.
Mass, M.C., Thewissen, J.G.M., and Kapperman, J. 1998. Hyssamasia seni (Mammalia, Embrithopoda) and other mammals from the Eocene Kartal Formation of Turkey. Bulletin of Carnegie Museum of Natural History 34: 286–297.
McKenna, M.C. and Bell, S.K. 1997. Classification of Mammals Above the Species Level. 631 pp. Columbia University Press, New York.
Marivaux, L., Vianey−Liaud, M., and Welcomme, J.−L. 1999. Première découverte de Cricetidae ( Rodentia , Mammalia) oligocènes dans le synclinal Sud de Gandoï (Bugti Hills, Balouchistan, Pakistan). Comptes Rendus de l’Académie des Sciences, série IIa 329: 839–844.
Marivaux, L. and Welcomme, J.−L. 2003. Additional diatomyid and baluchimyine rodents from the Oligocene of Pakistan (Bugti Hills, Balochistan): systematic and paleobiogeographic implications. Journal of Vertebrate Paleontology 23: 420–434.
Marshall, L.G., Case, J.A., and Woodburne, M.O. 1990. Phylogenic relationships of the families of marsupials. In: H. Genoways (ed.), Current Mammalogy, Vol. 2, 433–505. Plenum Press, New York.
Mein, P. and Ginsburg, L. 1997. Les mammifères du gisement miocène inférieur de Li Mae Long, Thaïlande: systématique, biostratigraphie et paléoenvironnement. Géodiversitas 19: 783–844.
Pilgrim, G.E. 1908. The Tertiary and Post−Tertiary freshwater deposits of Baluchistan and Sind with notices of new vertebrates. Records of the Geological Survey of India 37: 139–67.
Pilgrim, G.E. 1912. The vertebrate fauna of the Gaj series in the Bugti hills and the Punjab. Memoirs of the Geological Survey of India 4: 1–83.
Qi, T., Beard, K.C., Wang, B., Dawson, M.R., Guo, J., and Li, C. 1996. The Shanghuang Mammalian Faune, Middle Eocene of Jiangsu: History of Discovery and Significance. Vertebrata PalAsiatica 34: 202–214.
Raza, S.M.and Meyer, G.E. 1984. Early Miocene geology and paleontology of the Bugti Hills. Geological Survey of Pakistan 11: 43–63.
Simons, E.L. and Bown, T.M. 1984. A new species of Peratherium ( Didelphidae, Polyprotodonta ): the first African marsupial. Journal of Mammalogy 65: 539–548.
Storch, G. and Qiu, Z. 2002. First Neogene marsupial from China. Journal of Vertebrate Paleontology 22: 179–181.
Thewissen, J.G.M., Willams, E.M., and Hussain, S.T. 2001. Eocene mammal faunas from Northern−Pakistan. Journal of Vertebrate Paleontology 21: 347–366.
Welcomme, J.−L., Benammi, M., Crochet, J.−Y., Marivaux, L., Métais, G., Antoine, P.−O., and Balouch, I. 2001. Himalayan Forelands : palaeontological evidence for Oligocene detritic deposits in Bugti Hills (Balochistan, Pakistan). Geological Magazine 138: 397–405 .
Welcomme, J.−L. and Ginsburg, L. 1997. Mise en évidence de l’Oligocène sur le territoire des Bugti (Balouchistan, Pakistan). Comptes Rendus de l’Académie des Sciences de Paris, série IIa 326: 999–1004.
Jean−Yves Crochet [asprogeo@orange.fr], Laboratoire de Paléontologie, Institut des Sciences de l’Évolution, UMR−CNRS 5554, CC 64, Université Montpellier II, 34095 Montpellier Cedex 05, France, current address: 138 Ancien chemin du triadou,FR−34270 Saint−Jean−de−Cuculles, France (corresponding author);
Laurent Marivaux, Laboratoire de Paléontologie, Institut des Sciences de l’Évolution, UMR−CNRS 5554, CC 64, Université Montpellier II, 34095 Montpellier Cedex 05, France;
Pierre−Olivier Antoine [poa@lmtg.obs−mip.fr], Laboratoire des Mécanismes de Transfert en Géologie, UMR 5563 du CNRS, Université Toulouse, 31400 Toulouse, France;
Mouloud Benammi [mouloud@igeofcu.unam.mx], Laboratorio de Paleomagnetismo, Instituto de Geofísica,, Universidad National Autonoma de Mexico, 04510 Mexico DF, Mexico;
Nayyer Iqbal, Pakistan Museum of Natural History, 44000 Islamabad, Pakistan;
Grégoire Metais, Vertebrate Paleontology Section, Carnegie Museum of Natural History, Pittsburgh, PA 15213−4080, USA;
Jean−Loup Welcomme, La Confrérie, 34270 Le Triadou, France.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.