The Calymenina (“KAH-lee-meh-NEE-nah”) suborder of these animals is characterized by having its suture end at the genal (“jee-nal”) angle. A set of structures found in these animals can be classified into holochroal (“HOE-loe-krole”), schizochroal (“SKIT-soe-krole”), or abathochroal (“ah-BAH-thoe-krole”) subtypes. In 1999, a research group from the University of Manitoba discovered the largest one of these animals near Churchill measuring at 28 inches long; that animal is of the species Isotelus (“EYE-soe-tehl-uhs”) rex. These animals, which were the first to have evolved (*) compound eyes, proliferated by the end of the Terreneuvian (“TAYR-uh-NOO-vee-an”) series of the Cambrian era. Due to their similar appearance, horseshoe crabs are often erroneously stated to be the closest relative (10[1])to these invertebrates. For 10 points, (10[1])name these extinct (10[1])marine arthropods named for their “three-lobed” body organization. ■END■