Many kinds of animals have vanished from the earth.
喜んで = with pleasure… 喜んでいる = „being in pleasure“ 喜んで食べる = having pleasure of eating / eating with pleasure
しかし = howewer, but 儀式 = ceremony, ritual, rite, service 起こる = to occur; to happen 理解 (する) = understanding; comprehension; appreciation; sympathy
もしかしたら = perhaps, maybe …. 毛づくろい (する)= grooming oneself (esp. animals);
まま = as it is; as one likes; because; as
そのまま = without change; as it is / just like; extremely similar