The Rot Lord is a dinosaur.
There are no dinosaurs in Laskmeer, at least that we see. So a dinosaur would be unusual. The Rot Lord is unusual. He creates bugs, but he does this with magic, not laying eggs. So he doesn't have to be a bug. However, perhaps he traveled to our world and laid the first dinosaur eggs.
Keltnin Savos is a human from our world like Cardinal.
The prologue for "Web of Bones" shows that he was an apprentice of Gamoriel's before rebelling and becoming the Rot Lord. Gamorial may pluck disillusioned young men from modern America so she can groom them into her tools for whatever her goals are, and Keltnin took the power and ran with it.
