Abstract：
Lagerpeton chanarensis is an early avemetatarsalian from the lower Carnian (lowermost Upper Triassic) levels of the Chañares Formation, La Rioja Province, Argentina. Lagerpeton and its kin were traditionally interpreted as dinosaur precursors of cursorial habits, with a bipedal posture and parasagittal gait. Some authors also speculated saltatorial capabilities for this genus. Recent analyses indicate that lagerpetids are early-diverging pterosauromorphs, a hypothesis that invites a review of most aspects of their anatomy and function. A revision of available specimens and additional preparation of previously known individuals indicate that Lagerpeton lacked a parasagittal gait and was probably a sprawling archosaur. This latter inference is based on the femoral head articulation with the acetabulum. The acetabular rim has a strongly laterally projected posteroventral antitrochanteric corner, which results in a position of the legs that recalls that of sprawling living reptiles, such as lizards, and departs from the parasagittally positioned limbs of dinosaurs. This may indicate that early pterosauromorphs had a sprawling posture of their hindlegs, casting doubts on the significance of bipedal posture and parasagittal gait for the radiation of early ornithodirans, given that both traits have been regarded as key features that triggered the ecological and evolutionary success of the clade. Our results bolster recent claims of a high ecomorphological diversity among early avemetatarsalians.
摘要：
Lagerpetonchanarensis是Chañares组的下卡尼亚（最低上三叠纪）水平的早期avemetatarsalian，拉里奥哈省,阿根廷。Lagerpeton及其亲属传统上被解释为恐龙习惯的前体，双足姿势和矢状步态。一些作者还推测了该属的盐渍能力。最近的分析表明，角砾岩是早期发散的翼黄体，一个假设，邀请他们的解剖和功能的大多数方面的审查。对可用标本的修订和对先前已知个体的额外准备表明，Lagerpeton缺乏矢状步态，可能是散乱的弓龙。后一种推断是基于股骨头与髋臼的关节。髋臼边缘有一个强烈的横向投射后腹侧转子前角，这导致腿的位置让人回想起蔓延的活爬行动物，比如蜥蜴,并从恐龙的垂直位置的四肢出发。这可能表明早期的翼龙畸形的后腿姿势伸展，对双足姿势和矢状面前步态对早期鸟鼻虫辐射的重要性产生怀疑，鉴于这两个特征都被视为触发进化枝生态和进化成功的关键特征。我们的结果支持了最近关于早期avemetatarsalians中生态形态学多样性高的说法。
