Yeah, if the bones are what we can understand as Homosapien, then that would be descendants of Adam and Eve. For anything else, such as Lucy, that would be different types of monkeys. (People who believe in the theory of Macroevolution would of course disagree)
In other words, both Dr. Ross and the LCMS reject the idea that humans and monkeys have the same common ancestor that they gradually developed from, and that there is a spectrum of different human species. God's Word only allows for one human race, and there's a clear distinction between humans and animals in that humans are made in God's image.
So, for these monkey species, I suppose the LCMS would hold that they were created on the fifth day (Genesis 1:24) which would be before Adam and Eve, and then exist for a period after/contemporary with Adam and Eve.
Perhaps it's good to add here that the LCMS, being Orthodox Lutherans, only believe, teach, confess what the Bible say and try not to comment or speculate on what it doesn't say. In other words, being an Orthodox Lutheran means embracing mysteries. Dr. Ross comes from a Reformed tradition, where they are more inclined to poke into mysteries. This tendency has bled into the Lutheran Church on occasion. Anyway, I think Ross has done a much better job than the Higher Critics in Rome, and the theologically liberal Lutherans and Anglicans, because he does maintain a lot of important doctrines. So even if I disagree with his reasoning, I can appreciate that we have some unity of thought. So with respect to this topic of the distinction between man and animal, I'm glad Dr. Ross recognises it.