
Of course crocodiles aren't exactly the kind of animals that would just gnaw at something, so here's a sketch of the death roll animation:

I made it about 16.5 feet. Comparing it to the Auroch Beetle, it would look like this: http://prntscr.com/13n47lw
No, I don't think it should be walking around in a square like most mobs. I think it should be standing still and waiting like crocodiles do in real life.
That being said, here is it's info.:
Name: Crocodile
HP: 1000
Defense: 50
Power: 255
EXP: 157 (calculated)
Weight: 1600 lbs (comparable to a crocodile of similar size)
Description: Crocodiles are semi-aquatic reptiles found near lakes and rivers in Eliatopia. Like Earth crocodiles, the diet of Eliatopian crocodiles depends largely on their size. Baby crocodiles start off by eating insects and small fish. Juvenile crocodiles will eat prey such as squishers and larger fish. Sub-adults and small adult crocodiles will eat Swamp Crabs, Armed Dillos, and Shagdaws. Large adults, on the other hand, will eat large prey such as Grunts, Shellshockers, Great Frogs, and even Eliatopians. Thanks to the koala levels of stupidity exhibited by Eliatopians, Florida Man-level stories of Eliatopians being eaten by crocodiles are often found slipping under the radar of Xantis' watch. Opportunistically, crocodiles will eat the calves of Auroch Beetles and Gal Roaches. Thanks to their metabolism, crocodiles can go for a few months without food. While crocodiles are normally solitary, crocodiles may band together to protect their eggs and keep them from being eaten by Scorpees, Night Stalkers, Auroch Beetles, and Gal Roaches.
Now, for their drop pool.
Drops:
Wood Plank ($64; 12.5%; 8)
Big Squirt Gun ($100; 10%; 10)
Burger ($270; 5%; 13.5)
Straw Hat ($436; 2%; 8.72)
Rusty Dagger ($729; 1%; 7.29)
Survival Knife ($1331; 1%; 13.31)
Kunai ($1728; 1%; 17.28)
Bowman Hood ($3531; 0.5%; 17.655)
Ironclad Boots ($7869; 0.5%; 39.345)
Kevlar Pants ($13222; 0.4%; 52.888)
Goji Spine ($42507; 0.4%; 170.028)
Ironclad Helm Hood ($56514; 0.08%; 45.2112)
Ironclad Cloak ($56514; 0.08%; 45.2112)
Ironclad Pants ($56514; 0.08%; 45.2112)
Stage 3 Sharpening Stone ($3; ???)
Stage 4 Sharpening Stone ($4; ??? (1/2 S3 drop rate))
Total Loot Value: 493.6496
That should be good enough for an early post-Moonchyllus mob. Yep.