Data from: The ‘duck-billed’ dinosaurs of Careless Creek (Upper Cretaceous of Montana, USA), with comments on hadrosaurid ontogeny

The Careless Creek Quarry (CCQ) is a multitaxic bonebed in the Campanian Judith River Formation of south-central Montana (USA) that produced a diverse assemblage of vertebrates, including several dinosaurian clades. We describe the morphology of the CCQ hadrosaurid material and reevaluate its taxonomic affinities. Our osteological comparative observations, coupled with maximum parsimony phylogenetic analyses, indicate that the majority of the hadrosaurid material is referable to kritosaurin saurolophines. Only an ischium is unambiguously referable to Lambeosaurinae. Most of the kritosaurin specimens likely represent a taxon that forms a polytomy with species of Gryposaurus and Rhinorex condrupus Gates and Sheetz, 2015. This form may represent individuals of either G. latidens Horner, 1992 or G. notabilis Lambe, 1914, or a new species cogeneric or not with Gryposaurus. The juvenile material exemplifies several patterns of mandibular and appendicular osteological variation previously observed in other hadrosaurids. However, it also shows some departures from the common trends, supporting the fact that not all skeletal growth changes can be generalized to all hadrosaurids.

粗心溪采石场（Careless Creek Quarry，CCQ）是一处位于美国蒙大拿州中南部坎潘期朱迪思河组的多分类群骨层，产出了涵盖多个恐龙演化支的多样脊椎动物组合。本研究对CCQ产出的鸭嘴龙科（Hadrosauridae）标本形态进行了详细描述，并重新评估其分类亲缘关系。通过骨骼学比较观察结合最大简约法系统发育分析，结果显示绝大多数鸭嘴龙科标本可归入克里特龙族（Kritosaurini）栉龙亚科（Saurolophinae），仅1件坐骨可明确归属于兰伯龙亚科（Lambeosaurinae）。多数克里特龙族标本大概率代表一类与栉龙属（Gryposaurus）物种及Rhinorex condrupus（Gates与Sheetz, 2015）构成多歧支的类群；该类群可能隶属于宽齿栉龙（G. latidens，Horner, 1992）或显著栉龙（G. notabilis，Lambe, 1914），亦或是与栉龙属同属或不同属的新物种。本次研究的幼体标本呈现了此前在其他鸭嘴龙类中观察到的多种下颌骨与附肢骨骼学变异模式，但同时也存在部分偏离通用演化趋势的特征，这佐证了并非所有骨骼生长变化均可推广至所有鸭嘴龙类的结论。