The International Union for Conservation of Nature, the experts, might just know what they are doing.
In case you want to debate more, usually means by definition: "under normal conditions; generally." Meaning something usually terrestrial spends time on the ground under normal conditions.
I know that Dumerils are defined as terrestrial. I just shared my experience with my Dumeril which contradict that. I also believe what i can observe and see with my own eyes