Systematics, Ontogeny, Osteology and Historical Biogeography of Paddlefishes (Chondrostei: Polyodontidae)

尽管这个家族的鱼类体型很小， 白鲟或Polyodontidae是非常感兴趣的， 比较解剖学家和古生物学家。 两种生之 种发生在中国的长江和 密西西比，和几个化石分类群是已知的西北 美国参考 比米斯和格兰德博士正在研究 生物和化石物种以及生物的个体发育 形式，以确定其历史渊源和历史年表。 他们主要关注三个主题：1。进化 白鲟化石与现生鱼类的关系及其 对其他辐鳍鱼类研究的意义; 2.的 极端解剖学特化的起源，如 过滤器进料的修改和 电受体;和3.非常间断分布 生活在北美洲和中国。 三个实际因素使研究成为可能和及时： 1.最近在怀俄明州的收集工作已经产生了一系列 保存异常完好的鲟鱼化石; 2.一件新化石 来自蒙大拿州的物种已成为可供分析;和3。 公共鱼类孵化场开发的养殖方法 白鲟允许研究大系列的发育 阶段 结果从这个全面的比较解剖 研究活的和化石的形式将提高对 一般的鳍鱼的进化史和 特别是奇特的白鲟。

Despite the small size of this family of fishes, the paddlefishes or Polyodontidae are of great interest to comparative anatomists and paelontologists. The two living species occur in the Yangtze river of China and in the Mississippi, and several fossil taxa are known from western North America. Drs. Bemis and Grande are studying the anatomy of the living and fossil species as well as the ontogeny of the living forms, to determine their phylogeny and historical biogeography. They are focusing on three major topics: 1. The evolutionary relationships among fossil and living paddlefishes and their significance for studies of other ray-finned fishes; 2. The origin of extreme anatomical specializations, as represented by modifications for filter feeding and elaboration of electoreceptors; and 3. The extraordinary disjunct distribution of paddlefishes in North America and China. Three practical factors make the study possible and timely: 1. Recent collecting efforts in Wyoming have produced a series of unusually well-preserved fossil paddlefishes; 2. A new fossil species from Montana has become available for analysis; and 3. Methods developed by public fish hatcheries for the culture of paddlefish allow the study of large series of developmental stages. Results from this comprehensive comparative anatomical study of living and fossil forms will improve understanding of the evolutionary history of ray-finned fishes in general and of the peculiar paddlefishes in particular.