The diversification of flowering plants and marked turnover in vertebrate faunas during the mid-Cretaceous transformed terrestrial communities, but the transition is obscured by reduced terrestrial deposition attributable to high sea levels. We report a new fossil assemblage from multiple localities in the Upper Cretaceous Ferron Sandstone Member of the Mancos Shale Formation in Utah. The fossils date to the Turonian, a severely underrepresented interval in the terrestrial fossil record of North America. A large silicified log (maximum preserved diameter, 1.8 m; estimated height, ca. 50 m) is assigned to the genus Paraphyllanthoxylon; it is the largest known pre-Campanian angiosperm and the earliest documented occurrence of an angiosperm tree more than 1.0 m in diameter. Foliage and palynomorphs of ferns, conifers, and angiosperms confirm the presence of mixed forest or woodland vegetation. Previously known terrestrial vertebrate remains from the Ferron Sandstone Member include fish teeth, two short dinosaur trackways, and a pterosaur; we report the first turtle and crocodilian remains and an ornithopod sacrum. Previous studies indicate that angiosperm trees were present by the Cenomanian, but this discovery demonstrates that angiosperm trees approaching 2 m in diameter were part of the forest canopies across southern North America by the Turonian (~92 million years ago), nearly 15 million years earlier than previously thought.

中文翻译：

---

一种新的化石组合表明，北美洲（Turnian）（晚白垩世）生长了大型被子植物树。

在白垩纪中期转变的陆地群落中，开花植物的多样性和脊椎动物的显着更新，但是由于海平面升高而导致的陆地沉积减少，这种过渡被掩盖了。我们报告了犹他州Mancos页岩组上白垩统Ferron砂岩成员中多个地方的新化石组合。这些化石可以追溯到Turonian，在北美洲的陆地化石记录中，这一间隔严重不足。将大型硅化原木（最大保留直径为1.8 m；估计高度为约50 m）分配给了副叶lan龙属; 它是已知的最大的Campanian前被子植物，并且最早被记录为直径超过1.0 m的被子树。蕨类，针叶树和被子植物的叶子和类植物形态证实存在混合的森林或林地植被。费隆砂岩成员先前已知的陆生脊椎动物遗骸包括鱼齿，两条短恐龙轨道和一条翼龙。我们报告了第一个乌龟和鳄鱼遗骸以及鸟足骨。先前的研究表明，塞诺曼尼亚人存在被子植物树，但是这一发现表明，直径接近2 m的被子植物是土伦人（约9200万年前）在北美南部（大约9千5百万年前）森林冠层的一部分比以前想像的要多。