A new basal ornithopod dinosaur (Frenchman Formation, Saskatchewan, Canada), and implications for late Maastrichtian ornithischian diversity in North America
A new basal ornithopod dinosaur (Frenchman Formation, Saskatchewan, Canada), and implications for late Maastrichtian ornithischian diversity in North America
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DOI：
10.1111/j.1096-3642.2011.00735.x
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发表时间：
2011-12-01
影响因子：
2.8
通讯作者：
Russell, Anthony P.
中科院分区：
文献类型：
--
作者：
Brown, Caleb Marshall;Boyd, Clint A.;Russell, Anthony P.
产于萨斯喀彻温省法国地层(马斯特里赫特晚期)的一具小型关节基鸟足类骨骼(RSM P 1225.1)，以前被称为奇异龙分类单元，不同于该分类单元的两个公认种(奇异龙忽略分类单元和奇异龙Garbanii分类单元)。这些差异具有分类学上的信息，我们认为该标本为一新种奇异龙的正模式种。11月，通过存在两个同型异型体来诊断，并且表现出更类似于帕克氏龙的那些，而不是其他奇异龙种的那些倍型特征。法国人组还蕴藏着一个有趣的动物群组合，其中奇异龙代表了最丰富的恐龙分类群之一，并保存了许多恐龙分类群的较高比例的小标本(推测是幼体和亚成体)。进一步的工作将增加该地层的动物群样本，并允许与当代地层进行定量比较，这将决定这些差异是否得到很好的支持，并将确定它们最终的古生物学意义。对来自北美马斯特里赫斯晚期的第三种奇异龙的鉴定表明，该分类单元的多样性比之前认识的要多，并表明从坎帕尼亚到马斯特里赫斯晚期，多样性有所增加，这与大多数其他鸟纲支系的趋势形成了鲜明对比。(C)2011年伦敦林尼安学会，《林尼安学会动物学刊》，2011年，163,1157-1198。DOI：10.1111/j.1096-3642.2011.00735.x
A small, articulated basal ornithopod skeleton from the Frenchman Formation (late Maastrichtian) of Saskatchewan (RSM P 1225.1), previously referred to the taxon Thescelosaurus, differs from both recognized species of this taxon (Thescelosaurus neglectus and Thescelosaurus garbanii). The differences are taxonomically informative and we recognize this specimen as the holotype of a new species, Thescelosaurus assiniboiensis sp. nov., diagnosed by the presence of two autapomorphies, and displaying plesiomorphic traits more similar to those of Parksosaurus, than to those of the other Thescelosaurus species. The Frenchman Formation also harbours an intriguing faunal assemblage in which Thescelosaurus represents one of the most abundant dinosaur taxa, and preserves a relatively high proportion of small (putatively juvenile and subadult) specimens of many dinosaur taxa. Further work that increases the faunal sample from this formation, and that permits quantitative comparisons with contemporary formations, will determine whether or not these differences are well supported, and will determine their ultimate palaeobiological significance. Identification of a third species of Thescelosaurus from the late Maastrichtian of North America suggests that this taxon was more diverse than previously recognized, and shows an increase in diversity from the Campanian through the late Maastrichtian, contrasting the trends seen in most other ornithischian clades. (C) 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 163, 1157-1198. doi: 10.1111/j.1096-3642.2011.00735.x