Dentition and Jaw of Kokopellia juddi , a Primitive Marsupial or Near-Marsupial from the Medial Cretaceous of Utah

摘要: We add to the knowledge of dentition and lower jaw primitive marsupial or near marsupial, Kokopellia juddi, based on newly collected materials from medial Cretaceous (Albian–Cenomanian) central Utah. The dental formula, i4 c1 p3 m4, is for (or with respect to) Marsupialia, as are a number features dentary dentition: presence labial mandibular foramen, ?an inflected angle, ?and trace meckelian groove; lack “staggering” incisor series; “twinning” between entoconid hypoconulid molars; incompletely lingual position molar paraconid; upper protocone relatively small mesiodistally narrow; conules placed about halfway paracone–metacone. Other than stylocone, cusps lacking stylar shelf; we argue that this represents condition economy character change stratigraphic record marsupials in North America. Recent discoveries early marsupials, eutherians, therians metatherian–eutherian grade provide data indicating some derived (e.g., loss coronoid, groove, foramen; acquisition strong, “winged” conules, double rank postvallum/prevallid shearing, cusp D) probably arose independently, cases more once, among major groups tribosphenic mammals. In turn, suggests common ancestor placentals was has generally been appreciated.