Below you will see some links to pages presenting samples of early concept art and designs, including some which were subsequently shelved (or abandoned altogether) for the development of the Zootopia movie. This is a temporary introduction to some of the concept art which was used in developing the script, the settings, the characters, etc. In time, the format of this page may change, and we may post some of the concept art here directly.
Three members of the production team primarily contributed concept art for the development of the story, and much of it can be found floating around online. Those three team members are writer/director Bryan Howard, art director Matthias Lechner, and character designer Cory Loftis (who are each listed in the crew credits for Zootopia on the IMDB.com page for the movie). Keep in mind that this material is copyrighted, and the sole property of the Walt Disney Company. Also keep in mind that there are a lot of fan artists out there who are posting what they call may call "concept art" for Zootopia, but it is not actually official concept art.
Byron Howard: Has a background in animation and has directed other animated films, also going back to the 1990s (imdb.com). There is a page which features several of his conceptual designs.
Cory Loftis: Got his start in animation more recently than those mentioned above (imdb.com), but has worked on Wreck-It Ralph as well as Zootopia. This page shows some of his character designs, as well as those of Borja Montoro, whose credits in animation go back to the early 1990s, and who is listed as an "additional character designer" for Zootopia.
Here is another page (from the same website that features Cory Loftis' and Borja Montoro's art), showing more concept art from the movie.