Drawn for Dr. Thomas Holtz. Had to photograph this one as it was too large to scan.
Yes, the feather colors are extremely implausible. They are based on Luis Rey's caricature of Dr. Holtz as a tyrannosaurid in Dr. Holtz's encyclopedia. (In fact, entirely coincidentally, the palette reminds me of that of Pinkie Pie, with a lot more blue. As it happens, I don't find it difficult to imagine Dr. Holtz as a downplayed, more intellectual Pinkie Pie, constantly upbeat and enthusiastic during his lectures even despite certain recent events. And he's got the curly hair down too!)