Globidens

## GlobidensGlobe Teeth

### Temporal Range

84.9 - 66 million years ago, Santonian - Maastrichtian Stage, Late Cretaceous Period

## Characteristics

### Diet

Carnivore (Durophage)

* **Top Speed** of 13.5 - 16.2 kilometers (8.4 - 10.1 miles) per hour
* **Acceleration** of 3.75 - 4.5 meters (12 - 15 feet) per second
* Has globular teeth meant to crush hard-shelled prey

***Globidens*** (Globe Teeth) is a genus of mosasaur that lived 84.9 - 66 million years ago, from the Santonian stage to the Maastrichtian stage of the Late Cretaceous Period. It is known from various oceans around the world, from North and South America to Africa, the Middle East, and even Indonesia. The species depicted on Prehistoric Planet is likely *Globidens alabamaensis*, which lived in the Western Interior Seaway of North America.

## Paleobiology

### Size and Physique

***“ In the waters that surround North America, there are other giant predators. But they have no rivals. Mosasaurs. They may look like huge sharks, but they are in fact, a kind of aquatic lizard. Size, speed, and powerful jaws mean that very few creatures in the ocean are safe from these hunters. ”***

― **David Attenborough**, *North America*
*Globidens* is a medium-sized mosasaur around 5 - 6 meters (16 - 20 feet) long. Its weight is unknown, but based on mosasaurs of similar size, it was likely 1 - 2 metric tons (1.1 - 2.2 short tons) in weight. There are at least six species of *Globidens*, but given how the segment it is shown in takes place in the Gulf of Mexico, Prehistoric Planet likely depicted the type species, *G. alabamaensis*.

Fully-grown mosasaurs in general are large predators, mostly unchallenged and safe from most threats, and this is true for *Globidens*, but only to a certain extent. Given how it only grew slightly larger than a *Squalicorax* lamniform shark, *Globidens* would not have been the most dominant predator in the areas it thrived in, and would have likely been considered viable prey by large, predatory fish like *Xiphactinus* as well as other mosasaurs around two to three times its size, the largest of them being *Mosasaurus hoffmannii*, a cosmopolitan apex predator that dominated several Late Cretaceous oceanic ecosystems, including the oceans and seas where *Globidens* thrived.

### Jaws and Dentition

***“ Globidens has broad, rounded teeth that easily crack the ammonites' shell, releasing the air that keeps them buoyant. Without it, they sink helplessly to the seabed. ”***

― **David Attenborough**, *North America*
Most mosasaurs have bite forces powerful enough to crunch through the shells of turtles and ammonites, but none were as specialized in dealing with armored prey as *Globidens*, which is named for the spherical teeth in its jaws, clearly meant more for crushing through shells as opposed to gripping, puncturing, and tearing through flesh. Its durophagous diet is further supported by crushed inoceramid clamshells found in the remains of a *Globidens* specimen in South Dakota.

### Senses

*Globidens* is also shown occasionally flicking its forked tongue out. Mosasaurs are believed to have forked tongues, much like lizards and snakes, which collect chemical particles from the environment with their tongues and insert them into the voremonasal organ (also known as Jacobson's organ) by their palate. This feature still works very well for sea snakes, so it would also work just fine for mosasaurs. While usually depicted as long, slim and deeply-forked like those of snakes, Prehistoric Planet instead modeled their tongues after the shorter, thicker, and less-mobile tongues of anguimorph lizards, since mosasaurs are believed to be part of the anguimorph group themselves. However, while this means that mosasaurs are in the same group as varanids (monitor lizards), they do not seem that close to them, and mosasaurs may possibly not be anguimorphs at all.

### Speed

The speed of *Globidens* is not stated, though the segment it appeared in made it clear that it is quick enough to catch up with the ammonites it feeds on. Going off of calculations made in the Prehistoric Planet: Uncovered segment "How Fast Was A Mosasaur?", where it is said that a mosasaur can cover 75% of its body length in a single second, *Globidens*, being 5 - 6 meters (16 - 20 feet) long, can cover a distance of 3.75 - 4.5 meters (12 - 15 feet) in one second, or 13.5 - 16.2 kilometers (8.4 - 10.1 miles) per hour. It is possible that, given how it is only one-third the length and around one-eighth the mass of *Mosasaurus hoffmannii*, *Globidens* may have been, in theory, faster than these calculations (which are meant for mosasaurs the size and weight of *Mosasaurus*) make it out to be. Conversely, it is also possible that the extra mass and the greater amount of muscles and generated power allow the larger mosasaurs to accelerate with such great speed, and, due to being smaller and thus, lighter and packing lesser or proportionately weaker muscles, *Globidens* may not have accelerated to such great speeds, meaning that the calculation only works for mosasaurs possessing a similar length and mass as *Mosasaurus*. On the show, *Globidens* is not really shown relying on the "C-start" technique used by *Mosasaurus* and modern-day fish to achieve top speed, though this is probably not necessary for going after speeding ammonites.

## Paleoecology

### Paleoenvironment

*Main: Western Interior Seaway*

Main: Western Interior Seaway

***“ In the Gulf of Mexico, this Globidens mosasaur is searching for one particular kind of prey. ”***

― **David Attenborough**, *North America*
As shown on Prehistoric Planet, *Globidens* thrived in the warm, shallow waters of the Gulf of Mexico, which was, by that time, part of the Western Interior Seaway, an inland sea that split North America into two landmasses (Laramidia in the west and Appalachia in the east). It was also present in similar seas across the globe, like those in South America, Morocco, Angola, the Middle East, and what is now Timor Island by Indonesia.

### Hunting Tactics and Feeding Preferences

***“ Before the ammonites can escape, the mosasaur disables as many as it can. ”***

― **David Attenborough**, *North America*
*Globidens* showed a degree of predatory cunning, having anticipated and capitalized on the time when *Sphenodiscus* shoals come up to lay their eggs, using this knowledge to ambush them in an area the ammonites needed to pass through to get to their destination. It also attacked several of the ammonites in quick succession, simply crippling one before moving on to the next rather than taking its time to consume each prey it catches. That way, it is able to amass a larger amount of food, helpless on the seabed, a banquet it wisely accumulated so it can feed in peace after all the effort.

Although *Globidens* can easily crack the shell of the ammonites with its spherical teeth, which evolved specifically for tackling robust prey, it would prefer to only exert this effort when crippling as many as possible. When feeding at a leisurely pace, *Globidens* is shown ripping the soft bodies of its prey out of their shells instead. Even so, the presence of clam shells in the stomach of one specimen indicates that the mosasaur would have been fine crushing and swallowing prey while it was still in its shell.

## Appearance

### North America

In the second segment of North America, in the Gulf of Mexico, a *Globidens* seeks out shoals of "tiger ammonites", *Sphenodiscus*. Every year, from the deep levels of the ocean, thousands of females come up to the coast, each ammonite carrying hundreds of fertilized eggs that need to be laid in the shallows, right where *Globidens* is waiting for them, using its forked tongue to hone in on their location.

***“ Tiger ammonites are themselves hunters. The combination of a streamlined profile and a powerful siphon enables them to shoot through water at great speed. But so can the mosasaur. ”***

― **David Attenborough**, *North America*
The *Sphenodiscus* use their own predatory traits (their streamlined profile and powerful siphon) to get to their destination faster and evade incoming threats. Unfortunately for them, *Globidens* is also quick enough to catch up to them and attack. With its globular teeth, the mosasaur easily crunches through the shells of the ammonites, releasing the buoyant air within its prey, disabling and sinking as many *Sphenodiscus* as it can instead of taking time to consume each ammonite it catches. Once the shoals of ammonites have passed through the area, with no more prey to cripple, *Globidens* feeds on the ammonites it sunk to the ocean floor. Despite the mosasaur having killed hundreds of the ammonites, hundreds more make it to the shallows to successfully lay their eggs.

## Trivia

### General

1. ↑ 1.0 1.1 Contrasting preservation in pycnodont fishes reveals first record of regurgitalites from the Upper Cretaceous (Maastrichtian) Moroccan phosphate deposits
2. ↑ 2.0 2.1 Stomach contents of *Globidens*, a shell-crushing mosasaur (Squamata), from the Late Cretaceous Pierre Shale Group, Big Bend area of the Missouri River, central South Dakota

### Dr. Darren Naish

1. ↑ Openings on mosasaur palates may reveal the location of the Jacobson's organ, a palatal structure that lizards and snakes use in collecting chemicals from the environment via the tongue.
2. ↑ The tongues of the mosasaurs were based off of the shorter, thicker, and less-mobile tongues of anguimorph lizards.
3. ↑ Mosasaurs being close relatives of monitor lizards isn't really true. Assuming that mosasaurs are part of same group as monitor lizards, it appears that they don't seem particularly close, and it is possible that mosasaurs may not even be anguimorphs to begin with.

### Prehistoric Planet

1. ↑ 1.0 1.1 As stated in Prehistoric Planet: Uncovered - How Fast Was A Mosasaur?