Dinosaur Aliens (Kyoryu-Seijin) are a race of aliens that have taken refuge on the earth and therefore have become targets of a global alien extermination effort.
After Izumi's massacre, many of the people he killed were transferred to the Gantz room, along with him and Kurono. When Kurono tried to tell people what was going on, he punched him hard in the stomach, and knocked him out for awhile. Izumi then snuck off unseen and changed into his Gantz suit in a side room where he got a sword as well.
Gantz showed them a target called the Kappe alien, but as before, the picture shown isn't always the boss.
Insteadn they have to deal with a bunch of dinosaurs among them the a massive alien resembling a Brontosaurus appeared. It had a massive blade that projected from its skull, which it swung to cleave its opponents. Izumi used stealth mold to sneak up to it, and tried to kill it with his sword. His sword hit the blade on its head, which blocked his attack. Izumi then ran from it, it chasing him, and blasting about with a powerful energy beam attack. Kurono eventually realized that its brain is located in its torso and not the head, and shoots it there with an X-gun.
Though the mission ended, this brought a new wave of problems, as the missions ended the Vampire bosses lead by Hikawa made their first appearance and attacked a large portion of the remaining Gantz team that were still alive and killed most of them.