A common arthropod from the Late Ordovician Big Hill Lagerstätte (Michigan) reveals an unexpected ecological diversity within Chasmataspidida.

The large body size and well-developed appendage armature of Hoplitaspis reveals that chasmataspidids occupied a greater breadth of ecological roles than previously thought, with the abundance of available specimens indicating that Hoplitaspis was an important component of the local community. The miniaturization and ecological limiting of diploaspidids potentially coincides with the major radiation of eurypterids and may suggest some degree of competition between the two groups. The geographic distribution of chasmataspidid species suggests the group may have originated in Laurentia and migrated to the paleocontinents of Baltica and Siberia as tectonic processes drew the paleocontinents into close proximity.