Upper Cretaceous Vertebrate Fauna at Dzharakuduk, Kyzylkum Desert, Uzbekistan: Biostratigraphy, Biogeography, and Phylogeny

本工作的主要目标是：1)继续在Dzharakuduk(晚白垩世，Turonian？2)将这些重要的标本放在全球生物地层学、古生态学和生物地理学的背景下，3)继续对已经恢复的大量标本进行描述和系统发育分析。20世纪70年代末，已故的俄罗斯古生物学家Lev a . Nessov和学生们开始在乌兹别克斯坦Kyzylkum沙漠中部的Dzharakuduk进行实地研究，Nessov和PI于1994年继续进行研究，1997年由包括PI和副PI在内的11人组成的工作小组继续进行研究。这些研究以及由此产生的出版物表明，该地区是分类学上最丰富的地区（已报道的物种超过130多种），可以说是欧亚大陆最重要的晚白垩纪脊椎动物动物群之一。在世界著名的戈壁沙漠中，稍微年轻一些的遗址（晚白垩纪，坎帕尼亚）产生了更完整的材料，但在Dzharakuduk发现的更零碎的材料往往是精美的，保留了相当多的解剖细节，甚至是北美洲晚白垩纪遗址中几乎未知的整个头骨和肢体元素。过去在Dzharakuduk进行的广泛地面收集工作也于1997年进行，但在油田季节的最后三天进行了关键生产间隔的标记和密集干筛。在两天半的筛选和分类中（回收了10种哺乳动物）回收的脊椎动物（例如哺乳动物）标本几乎与前三周的地面收集（回收了15种哺乳动物）一样多。因此，在今后三个实地季节，在某些Dzharakuduk地点进行广泛的干筛将是至关重要的。扎拉库杜克悬崖包括大约200米的沉积物。Nessov认为，Dzharakuduk的脊椎动物遗址是河流和咸水环境的结合，被海相岩石所覆盖和覆盖。下面的岩石被认为是Turonian的年龄，而悬崖上的岩石被认为是白垩纪和古近纪的上部。1994年，我们在悬崖顶部发现了一块菊石（后来被鉴定为三东期），证明那里没有古近纪的沉积物。在我们1997年更广泛的工作中表明，Dzharakuduk遗址都起源于河流，并被一系列长时间但年龄未确定的渗透事件所包围。下面的沉积物肯定是边缘海洋，但确定一个时代仍然是难以捉摸的。上面的沉积物范围从边缘海洋到完全海洋，并且在暴露的顶部附近产生了非常丰富的海洋无脊椎动物群（80多种）。一种稍低的无脊椎动物群也发现了数千颗鲨鱼牙齿（12-15种）。这两种动物群都需要详细的研究，但它们的年龄从圣东纪到坎帕纪早期不等。这一非常初步的分析表明，早前对Dzharakuduk大陆脊椎动物遗址的Coniacian时代的评估可能是正确的，或者更年轻的Santonian时代是可能的。沉积物样品产生了各种微化石，但我们等待资金准备和研究这些以及大型无脊椎动物。代表Dzharakuduk低海岸平原的河流遗址在古生态学上与北美晚白垩世的遗址非常相似，但与戈壁的遗址非常不同，后者更多地是高地，干燥和风成为主。在Dzharakuduk和北美晚白垩纪，大量的鱼类，包括鲨鱼、两栖动物和水生海龟，强烈地表明了这种古生态的相似性，但只有在资金充足的情况下，才能进行更彻底的比较，以便完成分类、管理和动物分析。除了脊椎动物和无脊椎动物的区系分析和古生态解释外，这项工作的一个非常重要的组成部分是对选定的分类群进行系统发育分析。Nessov和他的学生用俄语发表了许多关于脊椎动物动物群各个方面的较短的论文和更大的、大多是概括性的目录，但更大、更详细的研究已经开始，涉及各种脊椎动物分类群。最近，Nessov、PI和Kielan-Jaworowska（1997）发表了第一篇关于Dzharakuduk脊椎动物的专著，包括系统发育分析。这是一项关于“zhelestids”α级分类学的专题研究，以及对这些胎盘哺乳动物的系统发育分析，显示了它们与它们的姐妹分类群Ungulata（各种现存的分类群加上现存的有蹄类、亚有蹄类和鲸鱼）的关系，后者在Dzharakuduk“zhelestids”大约2000万年后才出现在K/T边界附近。根据这些来自Dzharakuduk的“zhelestids”，PI能够命名和描述一种新的超级哺乳动物分类——蹄形动物。拟议的拨款将允许恢复和研究来自Dzharakuduk的其他脊椎动物，这些脊椎动物肯定会对系统发育研究产生同样的兴趣。

9804771ArchibaldMain objectives of this proposed work are: 1) to continue extensive collecting at Dzharakuduk (Late Cretaceous, Turonian? - Campanian), Kyzylkum Desert, Uzbekistan, 2) to place these important collection in a global biostratigraphic, paleoecologic, and biogeographic context, 3) and to continue the description and phylogenetic analyses of extensive collections already recovered.Field studies at Dzharakuduk, central Kyzylkum Desert, Uzbekistan were begun in the late 1970's by the late Russian paleontologist Lev A. Nessov and students, continued by the Nessov and the PI in 1994, and by a crew of 11 persons including the PI and co-Pi in 1997. These studies, and the publications that are beginning to result from them, demonstrate that this area is the taxonomically richest (over 130+ species have been reported) and arguably one of the most important Late Cretaceous vertebrate faunas in all of Eurasia. The slightly younger sites (Late Cretaceous, Campanian) in the world-famous Gobi Desert produce more complete material, but the more fragmentary material from Dzharakuduk is often exquisite, preserving considerable anatomical detail or even whole cranial and limb elements that are almost unknown from Late Cretaceous sites in North America. The extensive surface collecting that had been conducted in the past at Dzharakuduk was also done in 1997, but key producing intervals were flagged and intensively dry screened in the last three days of the field season. Almost as many specimens of vertebrates (e.g., mammals) were recovered in two and one-half days of screening and sorting (10 mammals recovered) compared all of the previous three weeks of surface colecting (15 mammals recovered). Thus, extensive dry screening at certain Dzharakuduk sites will be of key importance during the next three field seasons.The Dzharakuduk escarpment includes about 200 meters of sediment. Nessov argued that the vertebrate-bearing sites at Dzharakuduk were a combination of fluvial and brackish-water environments, underlain and overlain by marine rocks. The underlying rocks were argued to be Turonian in age, while those above in the escarpment were thought to be uppermost Cretaceous and Paleogene. The discover during our reconnaissance in 1994 of an ammonite (later identified as Santonian in age) at the top of the escarpment demonstrated that no Paleogene sediments were exposed there. During our more extended work in 1997 it was shown that the Dzharakuduk sites are all fluvial in origin and are bracketed by a series of peneplanation events of long, but undetermined age. The underlying sediments are definitely marginal marine, but establishing an age remains elusive. The overlying sediments range from marginal marine to fully marine, and have yielded a very rich fauna of marine invertebrates (80+ species) near the top of the exposure. A slightly lower invertebrate fauna also yielded thousands of shark teeth (12-15 species). Both faunas require detailed study, but are suggestive of an age as old as Santonian to as young as early Campanian. This very preliminary analysis suggesests the earlier assessment of a Coniacian age for the continental vertebrate sites at Dzharakuduk may be correct, or a slightly younger Santonian age is possible. Samples of sediments yielding various microfossils were made, but we await funding for preparation and study of these as well as the macroinvertebrates. The fluvial sites representing low coastal plains at Dzharakuduk are very paleoecologically similar to Late Cretaceous sites in North America, but are very unlike those in the Gobi, which are much more upland, dry, and aeolian dominated. The abundance of fishes including sharks, amphibians, and aquatic turtles at both Dzharakuduk and in the Late Cretaceous of North America stronly suggest this paleoecological similarity, but more thorough comparisons will only be possible if funds are secred to permit complete sorting, curation, and faunal analyses.In addition to faunal analysis and paleoecological interpretations of the vertebrates and invertebrates , a very important component of this proposed work is phylogenetic analysis of selected taxa. A variety of shorter papers and larger, mostly synoptic catalogies have appeared (mostly) in Russian by Nessov and his students on various aspects of the vertebrate fauna, but larger, more detailed studies have begun on various vertebrate taxa. The first monographic treatment of vertebrates from Dzharakuduk including a phylogenetic analysis was recently published by Nessov, the PI, and Kielan-Jaworowska (1997). This a monographic study of the alpha-level taxonomy of "zhelestids" as well as a phylogenetic analysis of these placental mammals showing their relationships to their sister taxon Ungulata (a variety of extict taxa plus the extant ungulates, sub-ungulates, and whales), which do not appear until near the K/T boundary some 20 million years after the Dzharakuduk "zhelestids". Based on these "zhelestids" from Dzharakuduk the PI was able to name and describe a new superordinal taxon of mammals, the Ungulatomorpha. The proposed grant will permit the recovery and study of other vertebrates from Dzharakuduk that will surely be of equal interest for phylogenetic studies.