Cheiruridae

Cheiruridae is an extinct family of trilobites, a group of arthropods that lived during the Paleozoic Era. These trilobites are characterized by their distinctive spiny exoskeletons, particularly prominent genal spines (spines extending from the cheeks) and pleural spines (spines projecting from the sides of the thoracic segments). The glabella, the central raised lobe of the head shield, is typically bulbous and ornamented. Cheirurids are found in marine sedimentary rocks dating from the Ordovician to the Devonian periods, with their peak diversity occurring in the Silurian. Their fossils are geographically widespread, indicating a global distribution.

The family Cheiruridae encompasses a variety of genera, each with subtle differences in their morphology. For example, some genera like Cheirurus itself are well-known for their elaborate spination, while others might exhibit more subdued ornamentation. The function of these spines is a subject of debate among paleontologists, with theories suggesting roles in defense against predators, buoyancy control, or even inter-specific recognition. The intricate and often elaborate nature of their exoskeletons makes cheirurids popular among fossil collectors. Their presence in the fossil record provides valuable insights into marine ecosystems of the Paleozoic.