Old (80s?) children's sci-fi book about everyone turning into dinosaurs

Question

There is a book I read as a kid that I'm trying to track down. It was a children's sci-fi book where everyone other than the main character turns into a dinosaur. Or rather, the main character woke up in a mirror universe where everyone is a dinosaur, and they need to get back to the human universe. In this universe he has to hide, because humans are extinct and everyone freaks out. I seem to recall this was caused by some science experiment, and the main character needed to help some mad scientist complete the experiment to send him back.

I've tried to find this by doing google searches, but I mean, there's tons of children's books about dinosaurs. Plus this particular book is pretty old, and the results are mostly flooded with stuff that's fairly recent.

Answer 1

Found a reddit thread here where someone asked a similar question, the answer was The Double Disappearance of Walter Fozbek, which was also made into an animated episode of CBS Storybreak. The book summary says:

Walter Fozbek wakes up to find himself the only boy in a universe where dinosaurs rule and humans are extinct, and his desperate attempts to get home are complicated by a black hole, an egotistical computer, and a mad scientist.

And here's the animated special on youtube:

There's a scene where they look at an ancient human skeleton in the dinosaur universe at 6 minutes 25 seconds in. And at 20 minutes in a dinosaur scientist explains that the human boy is from a "mirror world", which explains why he's right-handed instead of left-handed.