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（Campanian Judith River Formation）的多分类骨床，产出了包含多个恐龙演化支在内的多样脊椎动物化石组合。我们对该采石场的鸭嘴龙科（Hadrosauridae）标本形态进行了详细描述，并重新评估其分类亲缘关系。我们的骨骼解剖学比较观察结合最大简约法（maximum parsimony）系统发育分析结果显示，绝大多数鸭嘴龙科标本可归入栉龙亚科（Saurolophinae）下的克里特龙族（Kritosaurini）。仅一块坐骨（ischium）可明确划归赖氏龙亚科（Lambeosaurinae）。多数克里特龙族标本大概率代表一个分类群，该类群与雕齿鸭嘴龙属（Gryposaurus）物种以及2015年Gates与Sheetz命名的康氏鼻龙（Rhinorex condrupus Gates & Sheetz, 2015）构成多歧支系。该类群的个体可能隶属于宽齿雕齿鸭嘴龙（Gryposaurus latidens Horner, 1992）或是显著雕齿鸭嘴龙（Gryposaurus notabilis Lambe, 1914），亦可能是一个与雕齿鸭嘴龙属同属或不同属的新物种。该幼体标本展现了此前在其他鸭嘴龙科类群中观察到的下颌骨与附肢骨骼的多种解剖学变异模式，但同时也存在若干与普遍生长趋势相悖的特征，这佐证了并非所有骨骼生长变化都可被推广至所有鸭嘴龙科类群这一结论。