Fossil Club: Asaphid Trilobites from the Western United States, an Exceptional Window into Past Onto

The trilobite family Asaphidae represents a significant part of the taxonomic diversity of the Lower Ordovician in the Great Basin region of the western Laurentia (North American Craton) in the United States. These arthropods are notoriously known for being difficult to study due to their convergent, smooth, and effaced morphology. The trilobites of the Great Basin region, however, have been exceptionally preserved through silicification. This mode of fossilization allows us to recover 3D replicas of the original shell of the animal, preserving all of the exquisite details of the morphology. Silicification also preserves ontogenetic stages, from the smallest larvae to the adult. This exceptional material allows us an extraordinary window into the early evolution of this group, as well as abundant data on the developmental biology of arthropods from 480 million years ago.