19.5" Mosasaur Jaws (Platecarpus) - Exceptional Preparation

This is an very interesting and exceptionally well prepared specimen from the Late Cretaceous phosphate deposits of Morocco. It is a disarticulate jaw of a Mosasaur (Platecarpus ptychodon) with 15 original teeth present, 2 of which are only partially erupted. Nearly all Mosasaur jaws are found with similar crushing, but instead of removing all the bones from the pieces from the rock and reassembling them, they were left in place. It's also unique in that there is no restoration or compositing on this specimen, just a few crack repairs. A huge amount on preparation time was put into this specimen to remove the rock from not just in front of, but behind the teeth bringing them out in high relief.

The entire piece measures 19.5" wide, 14" tall and is up to 5.5" thick. About 60% of the sandstone has been backed with plaster for stability and it comes with a metal display stand. The portion of the sandstone that hasn't been backed with plaster has been stabilized with epoxy.

Mosasaurs are a family of enormous, marine reptiles that truly dominated the seas 90 million years ago. They ruled during the last 20-25 million years of the Cretaceous period. With the extinction of the ichthyosaurs and decline of plesiosaurs, mosasaurs diversified to become prolific, apex predators in nearly every habitat of the oceanic world.

Artists reconstruction of the mosasaur Prognathodon saturator.
Artists reconstruction of the mosasaur Prognathodon saturator.

Larger mosasaurs were the great leviathans of their time, extending 10–15 m, or 33–49 ft long. Hainosaurus holds the record for longest mosasaur, at a seemingly impossible, 57 ft. The smaller genera were still an impressive, 10–20 ft long. Mosasaurs probably evolved from semi-aquatic, scaled reptiles which were more similar in appearance to modern-day monitor lizards. They had double-hinged jaws and flexible skulls (much like that of a snake), which enabled them to gulp down their prey almost whole.

The gruesome, unchewed contents of fossilized mosasaur guts have revealed a varied diet of sea birds, ammonites, smaller marine lizards, possibly shark, and even other mosasaurs. Ammonites were especially crunchy mosasaur treats. They were abundant in the Cretaceous sea, and some Mosasaur had specialized teeth for the job.

Mosasaurs probably lurked for an ambush, rather than hunt, possibly using their powerful tail flukes for extra thrust to dart out and swallow unsuspecting prey. Non-reflective, keeled scales may have been a great advantage to the Mosasaur sneak-

Mosasaurs breathed air and gave birth to live young. The bronchi leading to the lungs run parallel to each other instead of splitting apart from one another as in monitors and other terrestrial reptiles. They were well-adapted to living in the warm, shallow, epicontinental seas of the period.

Although Mosasaurs diversified and proliferated at a spectacular rate, their specialization is considered the source of their demise when marine systems collapsed at the end of the Cretaceous.
Platecarpus ptychodon
Khouribga, Morocco
Phosphate Deposits
Entire specimen 19.5 x 14", up to 5.5" thick
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