A Deinosuchus alligator attacks a Agujaceratops dinosaur during the Aguja Formation.. A scene from what is now Big Bend Texas in the Aguja Formation. About 77 million years ago this was once home to the ceratopsian, Agujaceratops. A medium ceratopsian at 19-20 feet. This was also home to the largest Alligator to have ever lived, Deinosuchus. Deinosuchus has been estimated at 35-39 feet long and as high as ten tons. Agujaceratops might make for some substantial prey.