Mosasaurus

Name Origin

Lizard from the Meuse River

Family

Mosasauridae

Classification

Reptilia, Squamata, Lepidosauria

Habitat (Discovery Location)

Netherlands, United States, Japan

Period

79 to 65 million years ago (Late Cretaceous)

Length

Approximately 12 to 13 meters

Weight

Approximately 10 to 40 tons

Diet

Piscivore (Fish-eater)

Description

Mosasaurus was a giant marine reptile that ruled the seas during the Late Cretaceous period.

A giant marine reptile that ruled the seas in the Late Cretaceous period

Its name comes from the location where its fossil was first discovered, meaning “lizard from the Meuse River.”
Although it is sometimes treated as a dinosaur in media, it is, strictly speaking, a type of large lizard that returned to the sea, not a dinosaur.

Physical Characteristics of a Vicious Hunter

Mosasaurus could reach a length of 12 to 13 meters, making it one of the largest creatures to inhabit the seas at the time.
Along with other mosasaurids like Tylosaurus and Hainosaurus, it was an absolute ruler of the Cretaceous seas.

Its body was cylindrical, with a head that tapered to a point and sharp teeth for tearing prey.

It had sharp teeth for tearing prey

Its backward-curving teeth were designed to prevent prey from escaping once caught.
It is believed to have been an opportunistic predator, preying on anything it saw, including fish, ammonites, and even other marine reptiles.

While it was once thought to have a tail like a land-based lizard, recent research has revealed that it had a fin-like tail, similar to that of a shark or dolphin.
Its front and hind legs evolved into paddles, and it appears to have swum at high speeds by undulating its body from side to side.

Aggressive Nature and a Storied History of Discovery

Many fossils have been found with bite marks from other creatures.
This suggests that Mosasaurus not only preyed on other animals but also engaged in fierce territorial fights with other species, including its own kind.

The first Mosasaurus fossil was discovered in the late 1700s, and because the fossil was famously stolen as a war trophy, it was nicknamed “the monster of Maastricht.”
It was later formally recognized as an ancient reptile in 1822.

Its portrayal as a ferocious hunter in the film Jurassic World brought it great popularity due to its powerful presence. Fossils have also been discovered in Japan, where research is ongoing.

A vicious hunter

Discoveries in Japan and Its Diversity

Mosasaurus fossils are abundant in many countries around the world, and there have been discoveries in Japan as well.
There are over 20 species in the Mosasauridae family, so it is common practice in the paleontology community to specify the species when talking about Mosasaurus.

Its overwhelming power and mysterious ecology continue to captivate many people today.

Jurassic
Park / World Featured Dinosaur

Role in the Film (Spoiler Alert!)

Appearance in Jurassic World
The Mosasaurus made its series debut as a star attraction for the park. It boasts the largest size of any carnivore in the facility and is considered the largest carnivore in the entire franchise. It has 88 teeth.

The scene in the movie's trailer, where it spectacularly leaps from the water to grab a Great White Shark, left a powerful impression on audiences.

It normally inhabes the "Lagoon," a giant pool in the center of the park, where a spectacular feeding show (an attraction where it leaps to eat a Great White Shark) is held, much like a dolphin show.

Although only one Mosasaurus appears in the film, the park's lore states that three were housed in the facility. According to the keepers, the largest female individual has a "shy and bashful" personality. It is said that she often refuses to surface unless it is feeding time, and sometimes won't even show her face. Thanks to her internal implant, she never attacks the audience, suggesting she is somewhat acclimated to humans.

Her origin story dates back to August 25, 2000, when InGen scientists discovered traceable DNA fragments from a Mosasaurus specimen. The chief scientist, Dr. Wu, believed that if DNA could be extracted from sources other than mosquitoes trapped in amber, it might be possible to recreate aquatic life. After extensive research, he finally succeeded in bringing the Mosasaurus back to life.

The resulting individual was unveiled at Jurassic World and received rave reviews from the park's owner, Mr. Masrani. The Mosasaurus lived peacefully in the park's pool until the "incident" occurred.

In the film, besides the shark feeding show, she also stunned audiences when she dynamically devoured a Pteranodon that had accidentally flown over the Lagoon during the chaos, along with Zara Young, who was trapped in the Pteranodon's grasp.

Then, during the film's climax, as the Tyrannosaurus (Rexy) and the Velociraptor (Blue) were engaged in a life-or-death battle with the Indominus rex, the Mosasaurus suddenly leaped from the Lagoon and clamped down on the Indominus's neck. She dragged it underwater, killing it, thus playing an indirect but decisive role in Blue's victory and serving as the film's grand finale.