Hi Alexander welcome and thanks for sharing your first tests.
There's some good muscle reference over on Jun's Anatomy for Smilodons.
I noticed that there's kind of a large-ish gap in the musculature between the delts and the brachiocephalicus in your model. When you come to simulate the skin this will cause an obvious pocket so you might want to have another pass on your muscle configuration in that area.
As for animation, there's quite a bit of motion on the scapula. Could be wrong but I don't think they're quite that mobile. But still getting some nice response with the traps sliding over the scapula.
He looks to me like he's kind of sneaking. Is that the intent? Might be nice to see the front legs extend forward a little further?