Transformers: Age of Extinction opened with $100 million at the U.S. box office over the weekend, boasting the largest opening for any movie in 2014. Michael Bay’s fourth Transformers movie promised more robot action and upped the stakes by adding the popular robot dinosaurs known as Dinobots. That was more than enough to appease fans of the franchise, as these Dinobots were arguably the coolest part of the sequel.

Those Dinobots also increased the film’s wow factor in the trailers, and today we’re bringing you some really cool concept art that shows off what these metallic beasts looked like during the design phase. Artist Wesley Burt has released a huge batch of art related to the film, which will surely appeal to anyone who loves the Transformers film franchise.

Comic Book Movie has an entire series of pictures, which includes early examples of not only the Dinobots, but also artwork for characters Hound, Corvette and Crosshairs amongst others. Be sure to check it out when you’re done here, but first have a look at this collection of images highlighting the evolution of the Dinobots. Grimlock breathing fire is definitely our favorite. What's yours?