For David Krentz, a lifelong dinosaur fanatic, designing prehistoric animals was a dream come true. He recalls, "When I heard they were making a film about dinosaurs, I begged and kicked and pleaded until I got on it. Even before they hired me to work on the show, I'd bring material over and make suggestions about the design. I took a crack at designing the main character and gathered a lot of attention. "We had to walk a really fine line between reality and caricature," observes Krentz. "It was important to remember that these were characters first and foremost. Dinosaur facial muscles tend to be minimal so we had to take quite a few liberties. In the case of Aladar and the other Iguanodons, we threw in some horse facial muscles. We also added eyebrows and mouth shapes to help make them more expressive. There was a big debate for awhile about beaks or lips and we eventually settled on the latter. We ended up putting lips over the beak. Body-wise, the Iguanodons are pretty close to reality and the musculature is essentially accurate. They actually had a bone in their eyebrow."
In terms of accuracy, the herd members range from "bang-on" (e.g. the Ceratops) to loose caricature (e.g. Eema the Styrachosaur). Included in the group of over 30 species are some that have never been seen on film before, including the Microceratops and the Ankylosaur (Url).
Krentz describes his assignment on the film as ''probably the most Nirvana—like experience that I'll ever have in my life. For three and a half years, they paid me to draw dinosaurs. It was just a dream come true to be able to bring dinosaurs to life. My mother still can't believe it. My career choices were paleontologist or animator. This is the best of both worlds. It was so much fun to work on that I couldn't wait for Christmas vacation to be over so I could get back to work."