Mosasaurus Beaugei Jaw In The Original Plaster Jacket 3.9ft [RARE]Beaugei arambourg mosasaurus lower mandible jaw measuring 3. 9ft. The Mosasaurs were a group of perfectly developed marine predators, resembling a crocodilian and lizard form, with gigantic double hinged jaws, with artillery of large teeth, fully equipped to tackle the once prehistoric and deadly oceans. Yet to be proven however it is believed the Mosasaurus family were able to unhinge their jaws for a more precise attack and with a much deadlier