Yanornithidae is an Early Cretaceous ornithuromorph clade that preserves the oldest direct evidence indicative of a piscivorous diet in avian evolution. The family hitherto contained only a single genus Yanornis and two putative species. The yanornithids are readily distinguishable from other Mesozoic avians in having a long rostrum packed with numerous teeth. Despite the discoveries of dozens of specimens, little is known about the taxonomical and ecomorphological diversity of this clade due to a lack of comparative studies. Here, we describe two new yanornithid taxa, Similiyanornis brevipectus gen. et sp. nov. and Abitusavis lii gen. et sp. nov., based on two nearly complete skeletons from the Early Cretaceous Jehol Biota. We perform a taxonomical reassessment of yanornithids and rectify the assignments of published putative Yanornis-like materials. The results show that Yanornithidae contains three genera and three species, which demonstrate a wide range of limb proportions that exceed the degree seen in other L early ornithuromorph clades.

http://zoobank.org/urn:lsid:zoobank.org:pub:64C621AF-48B7-499E-9F41-B6023B2E5F78

Yanornithidae是白垩纪早期的鸟嘴兽类进化枝，保留了指示禽类进化过程中食鱼性饮食的最直接证据。迄今为止，该家族仅包含一个亚诺尼斯属和两个推定物种。yanornithids很容易与其他中生鸟类区分开来，因为它的长长的讲台上长满了许多牙齿。尽管发现了数十个标本，但由于缺乏比较研究，对该进化枝的分类学和生态形态学多样性知之甚少。在这里，我们描述了两个新的yanornithid类群，即Similiyanornis brevipectus gen。等。十一月 和Abitusavis liigen。等。十一月，基于早白垩纪热河生物群的两个几乎完整的骨骼。我们对yanornithids进行了分类学重新评估，并纠正了已发布的假定Yanornis样材料的分配。结果表明，亚甲科（Yanornithidae）包含三个属和三个物种，它们显示出的肢体比例范围很广，超过了其他L早期鸟嘴兽类进化枝中所见的程度。

http://zoobank.org/urn:lsid:zoobank.org:pub:64C621AF-48B7-499E-9F41-B6023B2E5F78