ABSTRACT

Ornithopod dinosaurs are relatively common in the Cretaceous of Australia, particularly in the state of Victoria, which has yielded five taxa to date: two from the upper Strzelecki Group (upper Barremian–lower Aptian), and three from the Eumeralla Formation (upper Aptian–upper Albian). Whereas four of these are based solely on cranial material, Diluvicursor pickeringi is represented by a partial postcranium and is the only ornithopod specimen heretofore reported from the Eric the Red West (ETRW) site. Herein, we describe nine ornithopod dentulous elements from the Eumeralla Formation: seven from ETRW, and two from nearby sites. The four ETRW maxillae are divided into three morphotypes that are morphologically compatible with Leaellynasaura amicagraphica, Atlascopcosaurus loadsi, and cf. Galleonosaurus dorisae, respectively. Although this implies that Diluvicursor might not represent a distinct taxon, this is circumstantial. The new Leaellynasaura maxillae are evidently adult exemplars, contrasting with the juvenile holotype, whereas the sole Atlascopcosaurus maxilla is more complete than all previously referred specimens; consequently, revised diagnoses of both taxa are presented. Finally, the presence in the Eumeralla Formation of cf. Galleonosaurus—otherwise known only from the upper Strzelecki Group—implies that this taxon persisted from the Barremian to the Albian, and potentially indicates remarkable environmental stability in southeast Australia during the late Early Cretaceous.

摘要

鸟脚类恐龙在澳大利亚的白垩纪相对常见，特别是在维多利亚州，迄今为止已经产生了五种分类群：两种来自上 Strzelecki Group（上巴雷米亚 - 下阿普蒂安），三种来自 Eumeralla 组（上阿普蒂安 -上阿尔比安）。其中四个仅基于颅骨材料，而Diluvicursor pickeringi由部分颅骨代表，并且是迄今为止从埃里克红西部 (ETRW) 站点报告的唯一鸟脚类动物标本。在此，我们描述了来自 Eumeralla 组的九个鸟足类牙齿元素：七个来自 ETRW，两个来自附近地点。四个 ETRW 上颌骨分为三种形态类型，在形态上与Leaellynasaura amicagraphica相容，Atlascopcosaurus loadsi和 cf. Galleonosaurus dorisae，分别。虽然这意味着Diluvicursor可能不代表一个独特的分类群，但这是间接的。新的Leaellynasaura maxillae 显然是成年样本，与幼年正模标本形成对比，而唯一的Atlascopcosaurus maxilla比之前提到的所有标本都更完整；因此，提出了两种分类群的修订诊断。最后，在 Eumeralla 组中的存在 参见。帆船龙- 否则只能从上 Strzelecki 群中得知 - 这意味着该分类群从巴雷米亚到阿尔比安持续存在，并可能表明早白垩世晚期澳大利亚东南部具有显着的环境稳定性。