Download the building instructions here. Read the notes below. Download the LEGO Digital Designer here (also for free). Besides a .zip file with the LDD instructions, the download page also contains a .pdf and a Stud.io file. The last two files were were made by Rebrickable user Jmmelko, who kindly gave permission to distribute them.
The Nalligator (N.’s alligator) is made with bricks from the Lego set 31058 ‘Mighty Dinosaurs’, which I reviewed earlier.
If you look closely at the design and the pictures, you’ll notice that the last tail segment has a hole. After i finished the design, made the photos and this web page, I discovered that the box actually contains a spare 1×1 plate in green. That’s how the universe sometimes saves the designer.
Unfortunately, the 2×1 bricks with the claws on the rear legs easily let go. So if you play with the Nalligator, they probably fall off. Instead you can make the rear legs as in the picture of the prototype. You can even make them green instead of tan. To get two green inverse slopes you need to replace the one from the body with a tan-colored one. These simple claws don’t look great, but they hold a lot better.
This MOC is also on Rebrickable.