After capturing cave crocodiles, voracious cave crawlers and cave dragons from the last goblin siege, I tried to tame them. Cave crocodiles and cave crawler appear in the animals screen and it is possible to select trainer to tame them. After being tamed and receiving the tag, e.g. "+trained+" they disappear from the animals screen. Also the dwarf responsible from animal training cancels his job after getting to the animal with the message "no creature".