Mosasaurus Prognathodon Jaw In The Original Plaster Jacket 3.1ftPrognathodon giganteus mosasaurus mandible jaw measuring 3. 1ft preserved from the Turonian to Maastrichtian ages 93 to 66 million years ago, ages forming part of the greater time division of the Cretaceous era around 135 to 65 million years ago. The massive mandibles in the original partially articulated positions. The scientifically important specimen of what was once a formidable marine predator is encased in a burlap jacket, this helps aid