International: Biostratigraphy, Biogeography, and Phylogeny of Vertebrates from the World's Oldest Known, Eutherian Dominated Fauna (Dzharakuduk, Uzbekistan)

100米长的上白垩统Dzharakuduk剖面(乌兹别克斯坦的Kyzylkum沙漠)包括河流和海洋沉积物，产生了100多种脊椎动物。在这些地点采集微脊椎动物是由已故的俄罗斯古生物学家内索夫开始的，并由乌兹别克、俄罗斯、英国、美国和加拿大(URBAC)科学家组成的国际联盟继续进行。新发现的大型海洋无脊椎动物标本来自该剖面的上部，可与欧洲的模式剖面相对应，表明其年龄为科尼亚纪/桑托纪(约8500万年前)。这再次证实了潜在的陆地脊椎动物至少有8500-9000万年的历史，因此比更著名的戈壁沙漠遗址更古老。当地丰富的脊椎动物遗骸是支离破碎的，但往往保存着精致的细节。大多数化石被迅速掩埋，可能是被山洪暴发淹没，几乎没有重新加工。古生态与晚白垩世北美沿海平原相似。从新筛选的55吨基质中，翼龙、哺乳动物和恐龙的后颅骨和颅骨元素仍然很常见。在两栖动物中，火蜥蜴比青蛙更常见。在爬行动物中，水龟、鸭嘴龙和霸王龙的恐龙碎片很常见，而蜥蜴、小型兽脚类、甲龙、角龙和蜥脚类恐龙相对较少。鸟类是多种多样的，既有灭绝的种群，也有更接近现存鸟类的物种。这种类似啮齿动物的多瘤哺乳动物和有袋类哺乳动物的近亲很少见。真兽类哺乳动物是人类所属的哺乳动物群体，是Dzharakuduk最常见的哺乳动物物种，约有11个物种。其中包括世界上最早出现啮齿动物和兔子的种群的近亲，以及可能至少产生了七目有蹄哺乳动物和鲸鱼的种群。所有迹象表明，之前的工作才刚刚开始发现Dzharakuduk的化石财富。未来三年的工作将为这些8500-9000万年前的脊椎动物群提供许多剩余问题的答案。

The 100m, Upper Cretaceous Dzharakuduk section (Kyzylkum Desert, Uzbekistan) includes river and marine sediments that yield over 100 species of vertebrates. Collecting microvertebrates at these sites was begun by the late Russian paleontologist Nessov and has been continued by an international consortium of Uzbek, Russian, British, American, and Canadian (URBAC) scientists. Large, new collections of marine invertebrate from the upper part of the section that can be correlated to type sections in Europe, indicate a Coniacian/Santonian age (about 85 million years old). This reconfirms that the underlying terrestrial vertebrates are at least 85-90 million years old, thus older than the more famous Gobi Desert sites. Locally abundant vertebrate remains are fragmentary, but often preserve exquisite detail. Most fossils were rapidly buried, possibly by flash floods, with little reworking. Paleoecology is similar to the Late Cretaceous North American coastal plains. Postcranial and cranial elements of pterosaurs, mammals, and dinosaurs remain common from the newly screened 55 tons of matrix. Among amphibians, salamanders are much more common than frogs. Among reptiles, aquatic turtles, and hadrosaur and tyrannosaur dinosaur fragments are common, while lizards, small theropod, ankylosaur, ceratopsian, and sauropod dinosaurs are relatively rare. Birds are diverse, including both extinct groups, as well as species closer to living birds. The rodent-like multituberculate mammals and relatives of marsupial mammals are rare. Eutherian mammals, the group of mammals to which humans belong, are the most common mammalian species at Dzharakuduk, with some 11 species. These include the world's earliest relatives of the group that gave rise to rodents and rabbits, as well as the group that may have given rise to at least seven orders of hoofed mammals and whales. All indications show that previous work has only begun to uncover the fossil riches of Dzharakuduk. The next three years of work there will provide answers to many of the remaining questions regarding these 85-90 million-year-old vertebrate faunas.