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New data on the skull and dentition in the Mongolian late Cretaceous eutherian mammal Zalambdalestes. Bulletin of the AMNH ; no. 281

Show simple item record Wible, John R. en_US Novacek, Michael J. en_US Rougier, Guillermo W. en_US Mongolian-American Museum Paleontological Project. en_US Mongolyn Shinzhlėkh Ukhaany Akademi. en_US 2005-10-06T14:15:06Z 2005-10-06T14:15:06Z 2004 en_US
dc.description 144 p. : ill. ; 26 cm. en_US
dc.description Includes bibliographical references (p. 131-140). en_US
dc.description.abstract "Exquisitely preserved specimens of the late Cretaceous eutherian Zalambdalestes recently collected from the Djadokhta Formation (early Campanian) of the Gobi Desert by the Mongolian Academy of Sciences-American Museum of Natural History Expeditions are the centerpiece of a thorough redescription of this taxon's craniodental morphology. Resolved and amended are uncertainties and errors in prior descriptions based on poorer preserved specimens collected by earlier expeditions to the Gobi. Preserved and described for the first time in Zalambdalestes is the basicranium, including an ectotympanic bone and portions of the hyoid arch. Zalambdalestes with a skull length of nearly 50 mm is large compared with other Cretaceous eutherians. It is also highly specialized with a long, thin, tubular snout, large diastemata in the anterior upper dentition, and an elongated mesial lower incisor with restricted enamel. These specializations, though less extreme, are also present in the zalambdalestids Barunlestes from the slightly younger Barun Goyot Formation of the Gobi and Kulbeckia from the late Turonian and Coniacian of Uzbekistan and the Santonian of Tadjikistan. No phylogenetic analysis published to date includes enough taxonomic and morphological breadth to evaluate the relationships of Zalambdalestes. Nevertheless, we investigate the impact of our observations on seven phylogenetic analyses published since 1993 that include Zalambdalestes. A comprehensive phylogenetic analysis testing the relationships of Zalambdalestes is not included here, but it is expected to result from our ongoing efforts to produce a phylogeny of basal tribosphenic and therian mammals. Currently, zalambdalestids are viewed either as stem eutherians or as having affinities to Glires (lagomorphs and rodents). Our comparisons with other extinct and extant taxa support a position for Zalambdalestes within Eutheria but outside the crown-group Placentalia. Supporting this basal position for Zalambdalestes are such primitive features as the last upper incisor in the maxilla, nasals broadly expanded posteriorly to contact the lacrimals, pterygoids meeting on the midline, and the position of the glenoid fossa on the zygoma and not the braincase proper, in addition to the occurrence of epipubic bones reported previously. Zalambdalestes shares a number of apomorphies with Asioryctitheria, the clade including the Mongolian late Cretaceous Asioryctes, Ukhaatherium, and Kennalestes. Among the unusual specializations supporting a zalambdalestid-asioryctithere clade are: the postglenoid foramen anterior rather than posterior to the postglenoid process; the postglenoid and entoglenoid processes of the squamosal continuous; a fusiform ectotympanic expanded laterally and contacting the entoglenoid process; a suprameatal foramen in the squamosal; a crista interfenestralis connecting from the petrosal promontorium to a fingerlike tympanic process behind the round window; a large piriform fenestra in the anterior roof of the tympanic cavity, which transmitted the ramus inferior of the stapedial artery endocranially to the orbit; a foramen ovale between the alisphenoid and squamosal; and a medially positioned internal carotid artery. All but the last two of these specializations are reminiscent of those occurring in various extant lipotyphlans, including taxa placed by recent DNA sequence analyses within Afrotheria and Eulipotyphla, and may provide a link between the Mongolian Cretaceous eutherians and lipotyphlans. The available sample of Zalambdalestes exhibits a remarkable degree of individual variation, including the incidence of the upper maxillary incisor, the first upper premolar, and the second lower premolar. The possibility exists that more than a single species, Z. lechei, is represented"--P. 3. en_US
dc.format.extent 5606101 bytes
dc.format.mimetype application/pdf
dc.language eng en_US
dc.language.iso en_US
dc.publisher New York, NY : American Museum of Natural History en_US
dc.relation.ispartofseries Bulletin of the American Museum of Natural History ; no. 281 en_US
dc.subject.lcc QH1 .A4 no.281, 2004 en_US
dc.subject.lcsh Zalambdalestes. en_US
dc.subject.lcsh Zalambdalestes lechei. en_US
dc.subject.lcsh Skull. en_US
dc.subject.lcsh Dentition. en_US
dc.subject.lcsh Mammals, Fossil -- Mongolia. en_US
dc.subject.lcsh Paleontology -- Cretaceous -- Mongolia. en_US
dc.subject.lcsh Paleontology -- Mongolia. en_US
dc.subject.lcsh Paleontology -- Gobi Desert (Mongolia and China) en_US
dc.title New data on the skull and dentition in the Mongolian late Cretaceous eutherian mammal Zalambdalestes. Bulletin of the AMNH ; no. 281 en_US
dc.type text en_US

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  • Bulletin of the American Museum of Natural History
    The Bulletin, published continuously since 1881, consists of longer monographic volumes in the field of natural sciences relating to zoology, paleontology, and geology. Current numbers are published at irregular intervals. The Bulletin was originally a place to publish short papers, while longer works appeared in the Memoirs. However, in the 1920s, the Memoirs ceased and the Bulletin series began publishing longer papers. A new series, the Novitates , published short papers describing new forms.

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