In a development that is fascinating even while sad, Thomas is now afraid of gazelles, period -- and has qualms about anything that looks (or sounds?) like a gazelle.
From the toy I mentioned before, his fear first spread to a picture in his bestiary. This book is a perpetual favorite. It resides near the potty and can entertain Thomas for a long time. But it has a picture of a gazelle in it. After the Terrible Gazelle Incident, Thomas looked a bit askance when I named the gazelle. He seemed to get more and more nervous about that photo over time. Now he can't even handle having the book open to that page, he just keeps pointing nervously to the gazelle over and over.
His fear has developed further, though. Not only is he worried about the gazelle picture, he is now fearful of the photos of deer and raindeer in the book too. My mom got him a raindeer in a rocking chair toy for Christmas. He is terrified when it starts to rock and doesn't like to see it, period. It's in the entryway hanging out with the gazelle now.
My dad's family got Thomas a set of hand puppets and a theater. He loves them all -- except the giraffe! He's frightened of the giraffe puppet and we had to move the box it was in out of his room. I'm not sure if it looks like a gazelle to him or if he's nervous because of the similarity of sound. In any case, he's not a fan of herbivorous plains dwellers from any biome.