Santa Saurus! is the 45th episode of Dinosaur King, in Series 1.
It's Christmas time at the Taylor house, and everyone is (being forced to) take part in the holiday festivities by having a costume party. On Zeta Point, Rod and Laura are remembering when they left their parents to go on the trip with Dr. Z, replaying their recording of the event over and over again. Meanwhile, Helga is occupying Dr. Z and the Alpha Trio with potentially toxic cooking. Dr. Z sees how down Rod and Laura look and decides to send them on a mission to capture the D-Team's dinosaur cards.
After distributing costumes from her college days (Dr. Taylor as Robin Hood, Zoe in a Santa-like outfit, Max as a snowman, and Rex as a pirate), Aki Taylor leaves to fetch her Christmas cake she'd had to order a month earlier. Unfortunately, Rod and Laura steal the cake to distract her for when they'd try to take the dinosaur cards from the house, but mid-plan, Aki unexpectedly happily invites them to join the party, much to the surprise and dislike of the D-Team, though Spike Taylor tells everyone to "bury the hatchet" for Christmas Eve and Aki forbids any fighting.
Immediately, however, Rod and Laura start snooping around the house for the cards, the pet-sized Terry and Tank get into a scuffle with the D-Team's pet dinos, and Rod and Laura get into a fight with Max and Zoe.
Back on Zeta Point, Helga's "cleaning" is doing more damage than cleaning, but when it knocks books off a shelf, Dr. Z finds inside one of the books the card of a difficult-to-control Secret Dinosaur of his that he'd forgotten about: Megalosaurus.
As Aki fixes Rod's hat torn in the fight, Aki and Spike begin to remind him and Laura about their own parents. And minutes later, an Alpha Droid spy sent to track Rod and Laura sees them joining in with the D-Team's celebrations, so Dr. Z gives the Megalosaurus card to the Alpha Trio and sends them to complete the mission.
At the party, Rod and Laura begin to enjoy themselves, with Rod even ignoring an opportunity to grab Zoe's Dino Holder when he sees it sitting unguarded on a desk. Then, the Taylors distribute Christmas presents to all five children (Rod and Laura's were last-minute): books filled with Aki's drawings of the kids' respective pet-form dinos, but Max also got a math study book (owing to his bad math grades seen in Mythical Mix Up). However, he doesn't like it and tosses it over his shoulder, where it lands on his mom's head. Both Dr. Taylor and Rod (but especially Rod) turn to scold Max, but Max tells Rod and Laura to leave, and they do. Zoe's Dino Holder disappears, too.
As they try to escape with the Holder, the D-Team catches up to Rod and Laura. The D-Team beats Terry and Tank, but then the Alpha Trio show up with Megalosaurus, who quickly goes on an undirected rampage. The dinosaur is finally defeated, though in the process shards of a boulder from the Time Warp Battlefield send the Alpha Gang flying and Zoe's Dino Holder falls, but Rod and Laura choose to pick up the drawing books Aki gave them instead of going after the Dino Holder, which Max retrieves. The collective Alpha Gang leaves.
Max apologizes to his mom, agreeing to use the math book, and they head back to the house, but Dr. Taylor refuses to use his Robin Hood guise to steal cake for the boys from Aki.
Rod/Laura vs Max/RexEdit
Terry runs up and smashes Ace across the face with his tail, then Tank charges Chomp and knocks him into Ace, and Terry throws them both into a Christmas display, causing Chomp to come out with reindeer antlers and Ace to be dressed in a Santa coat and hat.
Rex then has Ace use Mayfly, losing the Santa outfit, and defeats Terry and Tank.
Megalosaurus vs Max/RexEdit
The A-Team comes running up with the Megalosaurus card, but the Christmas lights cause the card to activate. Megalosaurus's appearance instantly sparks a Time Warp, and it charges forward, shattering small rocks in its way, and flips Chomp over onto Ace as it runs by.
Suddenly, a meteor shower starts pelting the landscape (it isn't clear if it's a Move Card or simply the effect of Megalosaurus's rage on a Time Warp), and everyone runs for cover. The Alpha Gang realize they have no control over the dinosaur as it uses Zero G Throw on Ace, defeating him.
Chomp hits Megalosaurus with Thunder Bazooka and kicks a sled from the Christmas display to knock the disoriented dinosaur off its feet, sending it crashing into a boulder, sending the shards flying into the Alpha Gang, which sends them flying. Exhausted, Megalosaurus returns to its card, defeated.
(Helga is dusting books off the bookshelf…)
-Helga: "Vork, vork, vork. So many messes to clean."
(…and walks a hole through the wall)
(the Alpha Droid sees Rod and Laura taking part in the D-Team's Christmas party)
-Ursula: "Oh no, it looks like Rod and Laura may have gotten caught sneaking in."
-Dr. Z: "And they're being forced to eat cake?"
(the Alpha trio arrives after Rod and Laura's defeat)
-Max: "Oh, no. It's the old lady."
-Ursula: "How dare you call me that! If I weren't so full of Christmas cheer and good will I'd stuff you up the chimney!"
(the Alpha Gang is making their getaway)
-Ursula: "Ed, you tell Dr. Z we didn't get the cards! Zander, you tell him we didn't bring back Megalosaurus!"
-Zander & Ed: "What about you?"
-Ursula: "I'll tell him I didn't have anything to do with it!"
- This episode shows the first seen image of the exterior of the undisguised Backlander, specifically the bottom of the column sticking through it, in Rod and Laura's recording.
- Dr. Z forgot about his Megalosaurus to the point of not including it in the total of 36 different types of dinosaur cards, though this number was already put into question.
- If even Dr. Z forgot Megalosaurus existed, how does Ed know what its Secret Move is called?
- This is the only episode that actually uses the term "A-Team" for the Alpha trio.
- In America, this episode wasn't aired during the first run-through of the series, only being added to the lineup in its proper spot after the episodes stopped at Tricks of the Traitor and restarted at Carnival of Chaos.
- This is the 4th Secret Dinosaur to have a nickname (though not in the dub) and to be seen as a chibi.
- When Chomp and Ace crash into the Christmas display, the costumes attach themselves onto the dinosaurs, suddenly switching from traditional to CG animation.