"Lake Valley Formation" The Lower Mississippian (Lower Carboniferous) Lake Valley Formation of southern New Mexico (USA) is home to the most diverse post-Devonian trilobite fauna in the world. This considerable late radiation of trilobites is accented by a wide array of bizarre morphologies, such as the uber-pustulose forms Piltonia (lower center part of the diorama). The reef-shelf harbored a rich fauna: fishes, Stethacanthus (a strange shark), crinoids, bryozoan colonies, and brachiopods to name but  few of the many organisms that occupied this ecosystem. Media: Adobe Photoshop. Click on arrows to get closer or view next illustration.