Geoffrey the Dinosaur was a copied version of Geoffrey the Gorilla Greg made when he was younger. When Susan told Greg to write a book, all the ideas Greg was coming with were taken, so Greg copied Geoffrey the Gorilla and edited it. He called his plagiarized version Geoffrey the Dinosaur which had the same lines, but only one change. The change was that Geoffrey was a dinosaur instead of a Gorilla doing things similar to a gorilla such as eating bananas and pounding his chest. Susan thought it was good since she didn't know there was a book called Geoffrey the Gorilla, so she sent it to a publisher in New York, but the publisher said that Greg plagiarized Geoffrey the Gorilla which was a best-selling children's book. Susan was mad at Greg for passing off the book as his own. But even though it was plagiarized, Greg was surprised that Susan could not figure it out herself from reading it.
- Diary of a Wimpy Kid: Cabin Fever (First and only appearance)
- Geoffrey the Gorilla - The original book, Geoffrey the Dinosaur is a plagiarized version of this book.