Eurybiall

Eurybiall is a genus of extinct marine arthropods that lived during the Late Cambrian period. The name is derived from the Greek words *eury* meaning broad and *biall* meaning joint, reflecting the broad, articulated exoskeleton characteristic of the group.

Fossils attributed to Eurybiall have been found in the Burgess Shale of British Columbia, Canada, as well as in similar mid‑Cambrian strata in the United States and China. The genus is typically identified by its distinctive carapace, which covers the thorax and can reach lengths of up to 15 centimeters. The exoskeleton is segmented, with each segment bearing a pair of long, jointed limbs. These limbs are thought to have been used for both locomotion and feeding, suggesting a benthic lifestyle in shallow marine environments.

Taxonomically, Eurybiall is placed within the family Eurybiallidae, which is part of the larger group of early arthropods known as pseudomorphids. The genus is known from about ten species, with *Eurybiall hutchinsoni* considered the type species. Comparative studies indicate that Eurybiall may have been a key transitional form between more primitive arthropods and later diversified lineages.

Paleontologists continue to study Eurybiall to better understand the morphological evolution of early arthropods and their ecological roles in Cambrian seas.