perohlaidid

Perohlaidid is a proposed, though not widely accepted, taxonomic order within the phylum Arthropoda. The concept of perohlaidid was put forward to group certain extinct marine arthropods, primarily from the Cambrian period. Organisms tentatively placed within this group are characterized by a distinct body plan, often featuring a segmented trunk with a series of paired appendages that are thought to have been adapted for swimming or other forms of locomotion. A key feature that has been discussed is the presence of a flattened, leaf-like body, which has led to the etymology of the group.

The fossil record for perohlaidids is limited, and many of the species initially considered part of this order have since been reclassified or remain subject to ongoing debate regarding their precise phylogenetic relationships. Their precise evolutionary position within Arthropoda is uncertain, with some researchers suggesting potential links to arthropod lineages that are now extinct, while others view them as an aberrant or poorly understood group. Due to the scarcity of diagnostic features and the fragmentary nature of many fossils, the validity and boundaries of the perohlaidid order are not definitively established within the broader field of arthropod paleontology.