Nintendo is dropping the details on Tyrunt and Amaura, a pair of fossil-based creatures in its upcoming Pokémon X and Y games.

In the upcoming Pokémon games (due out Oct. 12 for 3DS), you can pick between different fossils. The “Sail Fossil” will enable players to unlock the brachiosaurus-like Amaura. Meanwhile, by choosing the “Jaw Fossil,” players can instead get the T-rex-like Tyrunt.

Nintendo first teased this new pair of monsters in a video a few weeks ago, and now it’s detailing their abilities and evolutions.

Tyrunt and Tyrantrum

Tyrunt looks like a miniature tyrannosaurus rex. It is currently extinct and originally existed in a previous age over 100 million years before the events of Pokémon X and Y. It is a Rock- and Dragon-type creature, and its ability is Strong Jaw. Fitting his name, Tyrunt is only around 3-feet tall and weighs about 57 pounds.

Tyrunt evolves into Tyrantrum, which is much larger at 8-feet tall and 595 pounds.

Amaura and Aurorus

Amaura is a long-necked, brachiosaurus-style Pokémon. Like Tyrunt, it is 100-million-years old. It is a Rock- and Ice-type with the Refrigerate ability. Also like Tyrunt, it is pretty scrawny at around 4-feet tall and only 55 pounds.

Amaura evolves into Aurorus, which stretches out to 8-feet, 10-inches tall and weighs 496 pounds.