Vast leap in logic regarding Leviathan of Dis & "Leviathans"...

This has always bugged me, because I've never understood how the term for the dead reaper ends up being applied to the species responsible for creating the reapers...before anyone knew they existed and had a similar physical configuration.

The following is taken from the Fandom Mass Effect Wiki article on "Leviathan of Dis":
After meeting with Dr. Garret Bryson on the Citadel, Shepard will learn from a recorded conversation between Bryson and Admiral Hackett that Task Force Aurora had been investigating the Leviathan of Dis. Bryson's real interest in the Reaper corpse is the entity that killed it, which he identifies as the true Leviathan.

My question is...HOW can Bryson come to this conclusion? What could possibly motivate him to apply the name given to the dead reaper to the entirely unknown "thing" responsible for killing the reaper. Remember, NO ONE knew that the LoD WAS a reaper when it was first found. No one even knew what a reaper was. It only would have appeared to be a strange, ancient spaceship. There is ZERO evidence to suggest that the thing that "killed" the ship was a species that the ship/reaper was patterned after, and thus no reason at all to apply the same name given to the ship/reaper to the "thing" that killed the ship. There is no logical reason to say that the entirely unknown entity that killed the LoD is "the true Leviathan".

This is the "logic" portrayed in the game: You find the carcass of a _______ that you've never seen before, so with no information to go on, you conclude that the thing responsible for killing the _______ is the "true" _______. Huh????

Opinions or comments?

​