Dentition and jaw of Kokopellia juddi, a primitive marsupial or near-marsupial from the medial cretaceous of Utah

被引:55
作者
Cifelli R.L. [1 ,3 ]
De Muizon C. [2 ]
机构
[1] Oklahoma Museum of Natural History, Department of Zoology, University of Oklahoma, Norman
[2] URA 12 CNRS, Laboratoire de Paléontologie, Muséum National d'Histoire Naturelle, 75005 Paris
[3] Oklahoma Museum of Natural History, University of Oklahoma, Norman, OK 73019
基金
美国国家科学基金会;
关键词
Dentition; Marsupialia; Stylar cusps; tooth formula;
D O I
10.1023/A:1027394430433
中图分类号
学科分类号
摘要
We add to the knowledge of the dentition and lower jaw of the primitive marsupial or near marsupial, Kokopellia juddi, based on newly collected materials from the medial Cretaceous (Albian-Cenomanian) of central Utah. The dental formula, i4 cl p3 m4, is primitive for (or with respect to) Marsupialia, as are a number of features of the dentary and dentition: presence of a labial mandibular foramen, ?an inflected angle, ?and a trace of the meckelian groove; lack of "staggering" of the lower incisor series; lack of "twinning" between entoconid and hypoconulid on lower molars; incompletely lingual position of lower molar paraconid; upper molar protocone relatively small and mesiodistally narrow; and conules placed about halfway between the protocone and the paracone-metacone. Other than the stylocone, cusps are lacking from the stylar shelf; we argue that this represents the primitive marsupial condition based on the economy of character change and the stratigraphie record of marsupials in the Cretaceous of North America. Recent discoveries of early marsupials, eutherians, and therians of metatherian-eutherian grade provide data indicating that some derived features of the dentary and dentition (e.g., loss of coronoid, meckelian groove, and labial mandibular foramen; acquisition of strong, "winged" conules, double rank postvallum/prevallid shearing, and stylar cusp D) probably arose independently, in some cases more than once, among the major groups of tribosphenic mammals. In turn, this suggests that a common ancestor for marsupials and placentals was more primitive than has generally been appreciated. © 1997 Plenum Publishing Corporation.
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页码:241 / 258
页数:17
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