The mythic tale of Orpheus tells of his attempt to rescue his wife from the Underworld, who had died. Hades, moved by Orpheus' oratory and music, accepted Orpheus' plea to take his wife, Eurydice, home with him. But he gave Orpheus a warning. The return required a narrow path and a cave, and they would have to return in single-file -- should ever he look back to see if his wife was following him, she would remain in the Underworld forever. And sadly, that is what happened. Orpheus returned from the realm of the dead, but his wife did not. And for similar reasons, the Mongol hero Erlik did the same, traveling to the Underworld and back. But Erlik, unlike Orpheus, was also a mythic king, and his deeds were those of a ruler.
When Mongolian and Russian paleontologists found the Nemegt Valley in the 1950s, they spent much time there working over troves of fossils, and one of these would eventually be described by Perle Altangerel. The specimen: a skull and associated bits include a strange and broad foot with immense, raptorial-seeming claws. Perle chose to honor Erlik for he had rescued this ancient king from the Underworld, which had gone there and come back, through burial, fossilization and recover (its skull almost impecably preserved, missing a few bits here and there) and so christened it Erlikosaurus andrewsi. The species name honors Roy Chapman Andrews, another adventurous spirit.
When they were first announced to the world, they were described as theropods. But someone (Greg Paul) thought they looked an awful lot like prosauropods, too, so proposed they were a new group of dinosaur that was both prosauropod and ornithischian like. This has since been discarded.
We now know them to very very advanced theropods, closer to birds than are ornithomimosaurs, and very similar to dromaeosaurs, alvarezsaurs like Mononykus, and oviraptorosaurs.