I have to agree that falling damage has been modified, probably through the new physics stuff.
I've been doing a little !!SCIENCE!! on this, since my last siege left me with quite a large number of ... volunteers. About a dozen goblins, same number of war jabberers and a handful of giant rats. I also caught a couple of raccoons. I was hoping to drop the goblins in the hopes of making them explode, so I might get useful bones from them.
I started at 10z levels, and everyone was surviving. So I started experimenting. I tried dropping the jabberers, since they are big animals, I figured they would land harder and splat better. Nope. They survived also. Same thing with the raccoons and rats.
I dug down another 5 z-levels, leaving the landing pad at 15 z-levels below the drop zone. I figured, at this distance, anything hitting a solid floor is going to splat to bits. Nope. Still had plenty of survivors - probably 90%. The ones that died landed on their heads and immediately died from crushed brains. I had one giant rat that died of suffocation a while after landing and smashing his ribs and damaging his lungs. Even the jabberers - big and heavy as they are - all survived the drop. Although I only had one or two lucky deaths, everyone had multiple broken bones from the landing.
I would have kept digging but I started stationing the military under the drop zone since the vast majority of the critters I dropped were lying there unconscious from pain for the most part and the dorfs weren't interested in dragging them back upstairs to be re-dropped. So I ran out of volunteers.
Next siege will hopefully give me some more experimental subjects and I will dig further down and continue the experiments.
P.S. I wound up with over 2000 units of meat from all the jabberers. I have one stack of a couple hundred masterwork jabberer roasts that's work 94k dorfbucks. So it wasn't a complete waste of effort.