Paleozoic paleontology, with specialization in trilobites and other arthropods

为了阐明古生代（约5.43亿至2.45亿年前）的地球历史，我和我的学生收集和研究无脊椎动物化石。特别是，我们从世界各地收集三叶虫和其他节肢动物以及它们的踪迹。我们发现，描述和说明壮观的新化石，然后使用它们的形状，保存方式，多样性（物种数量）和发生模式的细节来创建有关古代事件的假设。 我们根据化石保存最好、最丰富但鲜为人知的地方来选择我们的野外区域。有了这些标准，我们发现的信息就更重要、更新颖。我们重建了过去世界的样子，以及生物体如何相互作用及其环境。我们工作的另一个重要方面是使用计算机分析这些化石生物的结构，以了解它们之间的关系，基于共同的进化进步，并创建反映这些关系的分类和命名方案。这导致了许多新物种的发现，甚至属或其他更高的类别。在最近的过去，我们还发现并描述了三叶虫（眼罩）和平板珊瑚（嵌在珊瑚虫软组织中的针状物）的新骨骼结构。从更广泛的意义上说，我们利用岩石切片中化石的出现和消失来将这些切片相互关联，并确定大规模灭绝事件的范围。然后，我们研究在这些灭绝时期留下的岩石，以找到这些灾难性事件发生的原因的线索。如果我们能够了解过去大规模灭绝的程度，我们可能能够在未来避免这种灾难。我的研究小组的工作应该大大提高我们对过去生物的认识，并帮助我们了解它们为什么，何时何地进化然后消失。我们发现的不同地区岩石之间的年龄相关性有助于了解这些地区岩石之间的时间和空间关系，并可能在油气和矿产勘探中具有重要的经济应用。

In order to illuminate Earth history during the Paleozoic Era (about 543 to 245 million years ago), I and my students collect and study invertebrate fossils. In particular, we collect trilobites and other arthropods as well as their traces, from a number of places around the world. We find, describe and illustrate spectacular new fossils, and then use details of their shapes, manners of preservation, diversity (numbers of species) and patterns of occurrence to create hypotheses about ancient events. We select our field areas based upon where the fossils are best preserved and most abundant, but are poorly known. With these criteria, the information we discover is more important and novel. We reconstruct what the world looked like in the past, and how organisms interacted with each other and their environment. Another important aspect of our work is the analysis of the structures of these fossil organisms, using computers, in order to understand their relationships, based upon shared evolutionary advances, and create classification and naming schemes that reflect these relationships. This has led to the discovery of many new species and even genera or other higher categories. In the recent past, we have also discovered and described new skeletal structures in trilobites (eye shades) and in tabulate corals (spicules embedded in the soft tissues of their polyp animals). In a broader sense, we use the appearances and disappearances of the fossils in the rock sections to correlate the sections with one another and locate the horizons of episodes of mass extinction. We then study the rocks laid down during these times of extinction to find clues as to why these catastrophic events took place. If we can understand past levels of mass extinction, we may be able to avoid such catastrophies in the future. The work of my research group should substantially improve our knowledge of past organisms, and help us to understand why, when and where they evolved and then disappeared. The age correlations that we find between rocks of different regions are useful for understanding the time and space relationships between the rocks in those regions, and may have important economic applications in the exploration for hydrocarbon and mineral deposits.