Don't act like you didn't know what I meant. For a variety of reasons, they don't push for the most realistic visual direction in any of their games.
The visual direction of Odyssey was supposed to be collage-esque: evoking the diversity of cultures across the world, making Mario look and feel like a foreigner, and addtionally playing into the theme of scrapbooking. To aid in that, they elected to include some reasonably realistic elements, so that the stylistic clash would be striking and memorable.
And besides, that T-Rex isn't actually realistic, recent studies show that they most likely had feathers and lips