Triceratops

The Triceratops is a three-part fossil that can be donated to the museum in all Animal Crossing games to date. It is the highest-scoring fossil (when complete) in terms of HRA points.

Completing the Triceratops in Animal Crossing
"Well now, if I'm not mistaken, I do believe this means... triceratops is complete! Hoo-WEE! Er, did I just say "hoo-wee"? Ugh. How terribly embarrassing, I sound like some blithering idiot. Let's move on, shall we? Here now... Where to begin? Triceratops... Yes... A member of the ornithischian order, this great beast flourished in the late Cretaceous period. It was a huge three-horned plant-eater, and grew up to 30 feet in length. That's 9 meters! Truly remarkable! Triceratops is easily recognized by its distinctive trio of horns and, of course, its parrot-like beak. Oh, and one mustn't forget the solid neck frill which provided it with fortification against giant predators. Triceratops was quite formidable indeed. In fact, it was one of the very last dinosaurs to suffer extinction. Oh, dear! Oh good gracious! Please, please forgive me. I tend to get a bit carried away. Dinosaurs, you know!"

Completing the Triceratops in City Folk
"...Stunning! The triceratops is done! Hoo, naught could make me happier! The triceratops was an herbivorous dino that lived until the end of the days of the dinosaurs. Its distinctive three horns and large collar belied its quiet nature. In actuality, the collarbone was the source of the beastie's mighty chewing power... But with powerful jaws like that, plus the horns, no carnivorous dino wanted a triceratops at its feet! HOO! I...beg your pardon! I was so enthralled, I... I spouted hot air like a boiling teapot, eh wot?"