Dinosaur Paleoecology, Judith River Formation, South CentralMontana

蒙大拿州的朱迪思河构造具有重要的历史意义，因为它是1856年约瑟夫·莱迪在费城发现的美国第一批恐龙化石的来源。然而，作为恐龙化石的来源，该地层一直令人沮丧。在阿尔伯塔北部和蒙大拿州中北部，年龄相近的地层已被证明产量更高。1981年，在蒙大拿中南部肖穆特附近的朱迪思河沉积物中发现了一个恐龙骨床，这是蒙大拿朱迪思河中发现的最丰富的恐龙骨床，也是该地层最南端的生产地点。所代表的分类群包括角鼻龙新属（Avaceratops lammersi Dodson 1986），一种巨型鸭嘴龙，一种非常罕见的厚头龙后颅骨，以及在这里出现频率高于大多数其他当代遗址的幼年鸭嘴龙和角鼻龙。工作最初集中在粗心溪采石场，但勘探发现了该地区的一些地点，因此建议建立一个从西到东朝向内河航道的环境样带。已经建立了一个25公里的样带，在它的东端发现了牡蛎，鲨鱼和硬骨鱼。对整个样带的动物区系变化的分析将有助于更好地了解恐龙分布的生态决定因素。

The Judith River Formation of Montana has historical significance as the source of America's first dinosaur fossils, which were described in Philadelphia by Joseph Leidy in 1856. However, the formation has since been frustrating as a source of dinosaur fossils. Beds of similar age farther north in Alberta and farther west in north central Montana have proved to be more productive. A dinsosaur bonebed discovered in 1981 in Judith River sediments near Shawmut, south central Montana, is the richest yet found in the Montana Judith River, and the southernmost productive site from this formation. Among the taxa represented are a new genus of ceratopsid (Avaceratops lammersi Dodson 1986), a giant hadrosaur, very rare postcrania of a pachycephalosaurid, and juvenile hadrosaurs and ceratopsids that occur with a higher frequency here than at most other contemporary sites. Work initially focused on the Careless Creek Quarry, but prospecting has revealed a number of sites in the area, so it is proposed to establish an environmental transect from west to east towards the Interior Seaway. A 25 km transect has been established, at the eastern end of which are found oysters, sharks and teleost fishes. Analysis of faunal changes across the transect will permit a better understanding of the ecological determinants of dinosaur distribution.