Skimmides

Skimmides are an extinct group of small marine arthropods known from fossil deposits dating to the late Silurian to early Devonian periods. They are distinguished by a broad, shield-shaped carapace and a segmented body with paddle-like appendages, features that set them apart from contemporaries such as trilobites. The group's exact relationships within Crustacea remain unsettled, and Skimmides are often described as a stem crustacean lineage or placed within crustacean incertae sedis in various classifications.

The name Skimmides derives from the Greek skimmein, meaning to skim, in reference to their presumed surface-oriented lifestyle. The organisms ranged from a few millimeters to a few centimeters in length and appear to have been benthic or nektobenthic, living close to the seafloor in shallow marine environments. Morphology is characterized by a broad shield-like carapace that covered the anterior body, a segmented trunk, and multiple pairs of lateral limbs used for locomotion and feeding. The absence or rarity of eyes in many specimens suggests adaptation to dim, sediment-rich waters.

Fossils have been recovered from several paleocontinents that formed shallow seas during the Paleozoic, indicating a fairly wide distribution. The Skimmides contribute to understanding early arthropod diversification and the evolutionary experiments in limb form and body plan that characterized Paleozoic crustacean-like groups.