Would a Tyrannosaurus Rex fit inside of the Dove Library?
Yes, a Tyrannosaurus Rex would be able to fit in the library, although s/he might not be able to get through the front door.
Our great hall dimensions from staircase to staircase (~ 35 feet), entrance to Information Desk (~ 25 feet), ceiling height (~ 35 feet) would accomodate a full-grown tyrannosaurus (approximate dimensions of 43 feet long and 13 feet tall at the hips).
From Dimensions Guide:
The T-Rex was one of the largest land predators during its time, which grew at an average length of 43 feet or 13 meters. Although some dinosaurs exceeded or even competed with its size, it was still considered the biggest carnivore in that period. At the hips, it measured approximately 13 feet or 4 meters high. The average T-Rex weighed more or less 7.5 short tons or 6.8 metric tons. It was an apex predator, which preyed on ceratopsians and hadrosaurs. However, some paleontologists believe that the T-Rex was more of a scavenger rather than an apex predator.