Prognathodon – whale-sized lizard of the deep

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Did you know?

Prognathodon are anguimorphs – part of the big group that includes modern-day alligators, monitor lizards and Gila monsters.

Vital statistics

Length: 6m long
Weight: approximately 2-3 tonnes (equivalent to almost two hippos)
Discovery:  named 1889 in Belgium, North American species recognised soon afterwards
Distinguishing features: streamlined head with chunky jaws, flipper-like limbs, vertical, shark-like tail fin

Chronotex field observations

As luck would have it, the lake next to TimeBase 67 contains a large Prognathodon that must have been there for several years, taking advantage of the regular appearance of the Triceratops herds. Adult mosasaurs are mostly solitary. Due to their fully aquatic nature and giant size, they’re also viviparous and have abandoned the production of shelled eggs, giving birth to live babies.

We’ve recorded attacks on swimming dinosaurs, as well as Prognathodon lunging out of the shallows to grab smaller dinosaurs who’ve strayed too close to the water’s edge.

Swimming isn’t performed with undulating sweeps of the whole length of the tail, but by leveraging the end section alone, in order to provide virtually all of the thrust. This gives the tail shark-like characteristics during swimming, and Prognathodon takes on an almost dolphin-like resemblance as it moves efficiently through water.

Key facts

  • A giant, flippered, fully aquatic reptile, a close relative of living monitor lizards like the Komodo dragon
  • Gives birth to live young in the water
  • Covered in tiny, overlapping body scales, the tiny ridges and grooves of which help in manoeuvring
  • Equipped with a forked tongue used to collect scent particles from water
  • Its vertical tail fluke gives it a shark-like appearance

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