Board Thread:Manga/@comment-29919227-20170107061428/@comment-26495049-20170107063051

A Titan shifter is defined as a human who is able to transform into a Titan at will.

The Quadrupedal Titan clearly possesses intelligence, which indicates a strong likelihood of it being a Titan shifter. However, as long as we have not seen its human form, we cannot rule out the possibility that it is a new breed of intelligent Titan created by Marley (or any other explanation you can think of).