Okay, I've heard a lot of people on these forums refer to Mosey as a Mosasaur and that's fine, but people who are referring to her as Mosasaurus (specifically Mosasaurus hoffmannii).. well that's just plain wrong.
An interview that was held at Comic Con 2011 with Richard Iggo who is the Senior Director of Marketing for Telltale Games confirmed that the Mosasaur is actually a Tylosaurus. Here is the link, http://www.youtube.com/watch?v=JQdm3zUP314&feature=related, and his comment can be found 2:30 minutes into the video.
Furthermore, the commentary on episode 4 from other members of the Telltale staff also specifically identify Mosey as being a Tylosaurus. I have noticed that on websites (specifically Park Pedia, Wikipedia, and occasionally even on these forums) Mosey is being identified as a Mosasaurus so I wanted everyone to simply be aware of the distinction.