A REVISION OF THE LATE CAMPANIAN CENTROSAURINE CERATOPSID GENUS STYRACOSAURUS FROM THE WESTERN INTERIOR OF NORTH AMERICA
A REVISION OF THE LATE CAMPANIAN CENTROSAURINE CERATOPSID GENUS STYRACOSAURUS FROM THE WESTERN INTERIOR OF NORTH AMERICA
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北美洲西部内陆晚期坎帕尼亚半甲龙角龙属戟龙属的修正
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
Anthony P. Russell
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作者：
M. Ryan;R. Holmes;Anthony P. Russell
在阿尔伯塔南部晚白垩世恐龙公园组上部30米处发现了一个多属的骨床和多个标本，并发现了一个单一的标本（S. ovatus），来自蒙大拿州两种药物形成的大约相同时间的沉积物。甲龙的关键颅部元素（鼻骨和眶后骨）似乎经历了类似的个体发育变化，就像在半人马龙身上记录的那样。虽然所有成年的中央龙类（除了中央龙）在P3位置的顶骨上都有类似尖刺的顶骨突起，但只有柱甲龙的P4突起是发育良好的尖刺。柱尾龙的P5-P7突起的形状在种内有变异，这些突起要么是其他中央龙类的典型的未修饰的冠状头端，要么是发育成短穗。S ovatus从蒙大拿州被保留为一个有效的种的基础上的自形收敛的P3尖峰向中线。
Abstract The centrosaurine ceratopsid genus Styracosaurus is known from multiple specimens and a multigeneric bone bed in the upper 30 m of the Late Cretaceous Dinosaur Park Formation of southern Alberta, and a single specimen (S. ovatus) from approximately time equivalent sediments of the Two Medicine Formation of Montana. Key cranial elements (nasals and postorbitals) of Styracosaurus appear to undergo similar ontogenetic changes as documented in Centrosaurus. Although all adult-sized centrosaurines except Centrosaurus apertus are known to possess spike-like parietal ornamentation at the P3 position on the parietal, only Styracosaurus has the P4 ornamentation expressed as a well-developed spike. Styracosaurus shows intraspecific variation in the shape of the more anteriorly placed P5–P7 ornamentation that are either the typical unmodified crest-shaped epoccipitals of other centrosaurines or are developed as short spikes. S ovatus from Montana is retained as a valid species based on the autapomorphic convergence of the P3 spikes toward the midline.