"The Pterodactyls are a search-and-"rescue" team of five. They like to sit back and let the often-treacherous storms in this part of the world do their dirty work, then reap the benefits of the devastation. But when these flying hunter-scavengers set their sights on Spot and Arlo, they’re in for a big surprise."
Like the other members of his flock, Thunderclap is a scavenger that follows storms to prey on trapped critters. He seems to be slightly deranged, having a sort of fascination and veneration for storms. He claims that he used to be scared and shy until he had a "relevation" when he saw "the Eye" of a storm. He believes that the storm freed him of fear. Thus, he renamed himself "Thunderclap", going by the motto that "the storm provides."
The Good Dinosaur
Following a violent storm, Arlo and Spot are found by the Pterosaur flock. At first, Thunderclap pretended to be friendly to Arlo; recounting to him his story. However, his true motives become apparent when he eats a small fox whole that Arlo helped to free. Thunderclap and the others then set their sights on Spot. Arlo and Spot flee and are saved when two young T. Rexes named Nash and Ramsey come to the rescue and scare the pterosaurs away.
Some time later, Arlo and Spot are stuck in yet another storm. Thunderclap and his gang find them again and they succeed in separating Spot from Arlo this time. They trap Spot into a old stump by a river and try to claw him out. With a newly-found courage, Arlo faces off the pterosaurs and easily defeats them by knocking them into the river. Arlo lets out a vicious roar, which terrifies Thunderclap, causing him to regain his sense of fear. Spot then tears a hole in a scared Thunderclap's left wing and as he tries to fly away, Arlo throws a stick at him and Thunderclap is rendered flightless as he crashes into the river.
It's uncertain of what happened to him after this, but it can be presumed that Thunderclap either drowned, washed ashore while being weakened, or was unable to fly ever again.
“Oh good, thank goodness for that, uh, Coldfront, Downpour, keep looking for wounded folks!”
“NO!, a "relevation"!”
—Thunderclap to Arlo about relevation.
“I was in a real low point, ya know?”
—Thunderclap explaining his life story to Arlo.
“Yeah "Wow!", that's when the storm gave me my new name.”
“The storm provides, you can call me Thunderclap.”
Thunderclap used to be frightful of the world around him. This changed when he was caught in a storm which no longer made him afraid. Following this, Thunderclap had a "revelation", realizing that the storm saved his life, therefore he must follow it. The experience made him insane and obsessed with the storm's power, turning him into a sadistic scavenger as he relied more on the animals caught in the storm, gleefully devouring them every time. While he may come across as affable towards dinosaurs at first, Thunderclap is harsh and unforgiving towards dinosaurs who help his prey escape, with no qualms towards harming them afterwards. Despite being in a group, he does not consider the other pterodactyls as his friends but rather fellow followers. He will not hesitate to fight them for any meal found. Any meal that manages to escape, he will pursue them relentlessly until they are devoured. Thunderclap presumably regains his lost sense of fear when he was frightened by Arlo's roar and desperately tried to flee after Spot tore a hole in his wing.
They both initially seem friendly to the main protagonist.
Thunderclap is also very similar to Soto from Ice Age.
They are both prehistoric animals (Soto was a Smilodon (Saber-toothed cat) and Thunderclap was a Nyctosaurus).
He shares his name with a monster of the week from Sailor Moon.
Thunderclap is also similar to Mrs. Griffin and Mr. Griffin from All Creatures Big and Small.
The three of them are flying creatures.
The three of them try to eat the heroes, but fail. Unlike Mrs. Griffin & Mr. Griffin who keep failing, Thunderclap only fails twice, but he's more sadistic while Mrs. Griffin & Mr. Griffin act like dimwits.
He shares his name with a moose named Thunderclap who appears as the main antagonist in the 1950 Disney short, Morris the Midget Moose. It's very possible that the Thunderclap from The Good Dinosaur was based on this character.
Thunderclap is the second Pixar movie villain to have met an ambiguous fate; the first is Lots-O' Huggin' Bear, the main antagonist of Toy Story 3.
Thunderclap is quite similar to Timber Wolf from Benji the Hunted. They both wanted to kill children (Thunderclap wanted to kill Spot; Timber Wolf wanted to kill the Cougar cubs).