Image: Wizards of the Coast
The next Magic: The Gathering set Ixalan will support a new creature type: dinosaurs, but as most Magic players already know, Ixalan is not the first Magic set to feature "dinosaur" creatures, so Wizards of the Coast just made a creature type update for the 14 cards that are considered dinosaurs from previous sets.
Check out their full list of creatures that will now be official Dinosaurs:
Source: Wizards of the Coast
So now, players who had been dreaming of building a dinosaur-themed Commander deck can finally build one. There are 33 tribal Dinosaur cards right now, and more coming from Ixalan, so I'm sure there will be enough cards to support that.
Wizards also revealed a new dinosaur from Ixalan, Regisaur Alpha:
Wow! That's great value. It looks like dinosaur tribal will be a thing in competitive Standard.
Here's the synopsis for Ixalan:
For centuries, the untamed jungles of Ixalan have hidden a coveted secret: Orazca, the city of gold. But no secret can remain undiscovered, and no treasure can be taken uncontested. Unfurl your sails, saddle up a dinosaur, and battle your rivals as you embark on a journey to claim the plane's greatest fortune for yourself!
Number of Cards: 279
Magic Open House: September 16–17, 2017
Prerelease Weekend: September 23–24, 2017
Release Date: September 29, 2017
Draft Weekend: September 30–October 1, 2017
Game Day Weekend: November 11–12, 2017
Magic Online Launch: September 25, 2017
Magic Online On Sale Date: September 29, 2017
Magic League Begins: October 2, 2017
Pro Tour Ixalan: November 3–5, 2017