Theropod, avian, pterosaur and arthropod tracks from the Latest Cretaceous of Paredon, Coahuila, northeastern Mexico, and their significance for the end-Cretaceous mass extinctiion

在DFG项目中，我们最近修改了两个独特的地点，其中结合了不寻常的鸟类、翼龙和恐龙足迹以及无脊椎动物的足迹，即节肢动物的足迹。这些地方(阿马戈斯，旧金山)是我们在萨尔蒂略以北约40公里的墨西哥科阿韦拉州拉斯恩西纳斯组的马阿斯特里赫斯蒂安硅屑三角洲沉积中发现的。大部分的履带是由至少五种不同类型的鸟类形成的，而Zhdarchoid翼龙的履带是罕见的，只发现了非鸟类兽脚类动物的单一足迹。因此，我们的初步数据提供了大量证据，证明在白垩纪末期之前，这一地区恐龙和翼龙的数量逐渐减少，鸟类也同时受到辐射。我们有证据表明，含有轨道组合的沉积物是在最新的马斯特里赫期沉积的。一个厚达2.5米的单元表明了这一点，其中含有丰富的蒙皂石球体，归因于距离阿马戈斯不到8.5米的上段希克苏鲁布撞击。Shenodisus pleurisepta是阿玛戈斯最后的菊石，可能已经越过K/PG界线进入最早的古新世。本文根据在该区发现的新的K/PG界线剖面，采用新的方法，记录了四足动物的地层赋存和周转情况，并对上述情景进行了讨论。此外，我们将对轨道进行专题性的生物化石学修订。

Within DFG project we recently revised two unique localities that combine an unusual diversity of avian, pterosaurian and dinosaur tracks as well as trails of invertebrates, namely arthropods. These localities (Amargos, San Francisco) were discovered by us in uppermost Maastrichtian siliciclastic delta sediments of the Las Encinas Formation in the Mexican state of Coahuila, about 40 km north of Saltillo. The majority of the trackways was produced by at least five different types of birds, while trackways of azhdarchoid pterosaurs are rare and only a single footprint of a non-avian theropod was found. Our initial data therefore provide substantial evidence for a gradual decline in this area of both dinosaurs and pterosaurs and simultaneous radiation of birds prior to the end of the Cretaceous. We have evidence that the sediment containing the trackway assemblage was deposited during the very latest Maastrichtian. This is indicated by an up to 2.5 meter thick unit with abundant smectite spherules attributed to the Chicxulub impact at less than 8.5 meters distance up-section at Amargos. Sphenodiscus pleurisepta is the last ammonite at Amargos and may have crossed the K/Pg boundary into the earliest Paleocene. We here propose to discuss the scenarios above by recording the stratigraphic assignation of sediments and the turnover in tetrapods based on new K/Pg boundary sections discovered by us in the area and by the application of new methods. Furthermore, we will execute a monographic ichnopalaeontologic revision of the trackways.