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中国肯氏兽—山西鳄组合带的新发现之二:山西二马营组幻阔齿兽(兽孔类:兽头类)一新种

发表日期:2015-01-21来源:放大 缩小

编辑:  俊,Fernando ABDALA

摘要记述了2012年在山西柳林三交二马营组上部采集的一个兽头类下颌标本,将其命名为幻阔齿兽三交种(Nothogomphodon sanjiaoensis sp. nov.)。新种以下列特征区别于属型种N. danilovi: 齿骨下缘起伏,犬齿基部卵圆形,犬齿与第一犬后齿间有显著间隙,犬后齿后缘无辅助齿尖。幻阔齿兽以其特殊的犬后齿形态与具裂齿的基干犬齿兽相似,它也是已知的唯一一类具有这种复杂裂齿齿系的兽头类。将俄罗斯的引鳄动物群与中国的肯氏兽-山西鳄组合带进行比较发现,幻阔齿兽是二者唯一共有的属,而中国的二马营组与克拉玛依组却没有共享的属。

关键词:山西柳林,中三叠世二马营组,兽头类

 

 

New discoveries from the Sinokannemeyeria-Shansisuchus Assemblage Zone: 2. A new species of Nothogomphodon (Therapsida: Therocephalia) from the Ermaying Formation of Shanxi, China

 

LIU JunFernando ABDALA

 


Abstract
  A new therocephalian specimen collected from the upper part of the Ermaying Formation of Liulin, Shanxi, China is named as Nothogomphodon sanjiaoensis sp. nov. This new species is differentiated from the type species Nothogomphodon danilovi by the following characters: dentary lower margin uneven; canine base is ovate rather than rounded; distinct diastema present between canine and first postcanine; absence of accessory cutting cusps on posterior border of the postcanines. Nothogomphodon has a postcanine morphology that resembles that of sectorial toothed basal cynodonts, which is the only evidence of therocephalians having developed this kind of complex sectorial dentition. Faunal analysis between the Russian Eryosuchus fauna and the Chinese Sinokannemeyeria-Shansisuchus Assemblage indicates that only Nothogomphodon is common to both faunas, whereas there is no common genus shared between the Chinese Ermaying and Karamayi formations. Therocephalians were present at a moderate level of diversity in Middle Triassic faunas from Laurasia, whereas nonmammaliaform cynodonts are only represented by two taxa. Conversely, in Gondwana cynodonts experienced an explosion in diversity in the Middle Triassic with the evolution of Gomphodontia, while therocephalians were scarcely represented in faunas of this age.
Key words   Liulin, Shanxi, China; Middle Triassic; Ermaying Formation; therocephalians

 
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