Oceans

* Title
* I
* IV
* VI

***“ Deep beneath the water’s surface, the world’s largest predator — the Mosasaurus — lies in wait to ambush unsuspecting prey. ”***

― The official Apple TV+ episode synopsis for *Oceans*
***Oceans*** is the fourth episode of the second season of Prehistoric Planet, and the ninth episode of the series overall.

## Segment I: *Phosphorosaurus*

* Grand Cayman Island, Central America
* Underwater Studio

**Oceans**, Segment I
**Setting**
Hakobuchi Formation, Hokkaido, Japan

**Filming Location**

* Grand Cayman Island, Central America
* Underwater Studio

***“ The ocean. The largest habitat on the Prehistoric Planet, and home to one of the biggest predators that has ever lived, a giant mosasaur. But not all mosasaurs are ferocious, 50 foot-long monsters... ”***

― **David Attenborough**, *Oceans*
The first segment of the episode, taking place somewhere in Hokkaido, a massive *Mosasaurus* swims close to a reef, prompting several of the area's inhabitants to scamper and hide. Even so, the point of the segment was to prove that not all mosasaurs are alike.

***“ Taking refuge in the reef is Phosphorosaurus. She too is a mosasaur, one of the smallest, at less than ten feet long. ”***

― **David Attenborough**, *Oceans*
In the maze of rocks and corals, a female *Phosphorosaurus* makes her way through as her bigger relative patrols the waters just outside her hideout, cautiously avoiding danger as she occassionally rises to the surface to breathe.

***“ She spends the daylight hours hiding from danger. But once or twice an hour, she has to dart to the surface to grab a breath. Like all of her kind, she is air-breathing. She's dwarfed by the biggest mosasaurs. But she too is a deadly predator. And she doesn't always hide in the shadows. When the time is right, she becomes a hunter. And that time is when the sun sets. ”***

― **David Attenborough**, *Oceans*
As night falls, *Phosphorosaurus* emerges from her sanctuary, seeking a particular type of food. In almost-total darkness, a massive shoals of lanternfish migrate, flashing their lights to confuse and disorient any predators that want to feast on them. But with her large eyes, *Phosphorosaurus* can visualize the dazzling display before her very well, charging several times through the shoals of fish to grab as many as she can.

***“ Their faint, eerie light is produced by a chemical reaction inside their bodies. A flash of this bioluminescence can be used to confuse predators. And when seen from below, the glow enables them to blend with - and hide against - the ocean's moonlit surface. But they can't hide from Phosphorosaurus. For her size, her eyes are the largest of any mosasaur, allowing her to see through the illusion and pick out her prey. ”***

― **David Attenborough**, *Oceans*
By dawn, as the lanternfish shoals descend back to the depths and the massive mosasaurs come out, once again prowling the reef, *Phosphorosaurus* returns to hiding in her sanctuary amongst the coral-encrusted rocks, waiting for nightfall to hunt once more.

## Segment II: *Hesperornis* and *Xiphactinus*

***“ By day, the prehistoric ocean provides opportunities for a very different type of hunter. In the warm, shallow seas of North America, fish numbers can almost match the nocturnal lantern fish shoal. ”***

― **David Attenborough**, *Oceans*
The second segment of the episode, by the warm, shallow seas of North America, a massive shoal of fish attracts many *Hesperornis*, with the flightless seabirds catching several fish with their beaks full of needle-sharp teeth.

***“ Xiphactinus, known as 'X-fish'. A feeding opportunity soon attracts them in large numbers. At over 17 feet long, they are one of the largest and fastest fish in the ocean. With its huge mouth, Xiphactinus can scoop up several fish at once, and has even been known to swallow prey half its size whole. At first, there is plenty for everyone. But as fish numbers dwindle, the X-fish turn their attention elsewhere. Predator is about to become prey. ”***

― **David Attenborough**, *Oceans*
The presence of the shoal soon attracts even larger predators. Several *Xiphactinus* arrive to take their share. But as the shoals of fish diminish, the X-fish, still hungry, seek out even larger prey to satiate their appetites.

***“ The Hesperornis have only one option; to swim for their lives. Xiphactinus is faster; Hesperornis is more agile. ”***

― **David Attenborough**, *Oceans*
Suddenly, several *Hesperornis* are attacked by *Xiphactinus*, with some even being swallowed whole. The surviving *Hesperornis* frantically attempt to escape the predators with evasive maneuvers. While *Xiphactinus* is faster, *Hesperornis* is more agile, allowing some of the birds to repeatedly dodge their pursuers just a second before getting grabbed and devoured.

***“ But in the eyes of an X-fish, anything is on the menu... even their own kind. Within minutes, the banquet is all but gone, and the predators move on. ”***

― **David Attenborough**, *Oceans*
Following this, one *Xiphactinus* is shown chewing on the body of a smaller X-fish, for their voracious appetites meant that any other living thing is nothing more but potential prey. With the shoal of fish reduced to nothing, the hunters leave the area.

## Segment IV: *Tuarangisaurus* and *Mosasaurus*

* Grand Cayman Island, Central America
* Underwater Studio

**Oceans**, Segment IV
**Setting**
Tahora Formation, North Island, New Zealand

**Filming Location**

* Grand Cayman Island, Central America
* Underwater Studio

***“ ... the very heart of the Pacific Ocean. These enormous atolls and the lagoons at their center provide the only shelter for thousands of miles. In this rare place, Tuarangisaurus, a kind of elasmosaur, finds safety. ”***

― **David Attenborough**, *Oceans*
The fourth segment of the episode takes place in the heart of the Pacific Ocean, where lagoons within atolls serve as the only sanctuary for thousands of miles. In these safe areas, several *Tuarangisaurus* take refuge.

***“ But outside these shallows is a different story. Each day, the elasmosaurs must venture into deeper water. Canyons in the atoll walls lead from the atolls to fresh feeding grounds. This deep water attracts not just the hungry elasmosaurs, but the predators that hunt them. The biggest in the ocean. Fifty foot-long Mosasaurus. ”***

― **David Attenborough**, *Oceans*
However, every day, the elasmosaurs need to hunt, and to do so, they must leave their shallow shelter and venture into the deeper waters of the open ocean. There, where nutrients rise from the ocean floor, thousands of fish gather, ensuring a plentiful supply of food for the elasmosaurs. In turn, however, they themselves become part of the menu of the rich feeding grounds. A fifty-foot *Mosasaurus*, the biggest predator in the Late Cretaceous oceans.

***“ Streamlined bodies and four powerful flippers give elasmosaurs great maneuverability. But their daily feeding forays make their movements predictable for an intelligent and patient hunter. Mosasaurus is an ambush predator. This enormous animal uses its huge tail to accelerate with astonishing speed. ”***

― **David Attenborough**, *Oceans*
As the elasmosaurs continue to feed, the *Mosasaurus* stalks them from the ocean floor, having predicted their movements due to their daily feeding forays. In one sudden movement, the mosasaur rushes upward and almost catches an elasmosaur, which manages to escape along with the rest of its pod. Unlucky in catching prey, the *Mosasaurus* retreats back to the ocean floor.

***“ This time, unlucky. In fact, most hunts fail. But with so many elasmosaurs living here, it’s not long before there is another opportunity. Camouflaged against the dark canyon floor, the Mosasaur can approach unseen, waiting for a young, inexperienced individual, the ideal victim. ”***

― **David Attenborough**, *Oceans*
With many elasmosaurs around, it didn't take long before another opportunity presented itself. Camouflaged against the ocean floor, the *Mosasaurus* awaits for an easy target, and rushes at it from below, emerging out of the water with the elasmosaur in its massive jaws.

***“ Mosasaurus can strike their prey with such force that the impact alone can kill. It's an attack so swift, the elasmosaur almost certainly never saw it coming. ”***

― **David Attenborough**, *Oceans*
The *Mosasaurus* circles around the *Tuarangisaurus*, which was instantly killed by its assault, floating just beneath the surface of the water. With the hunt over, the mosasaur grabs its prey and drags it to the bottom for it to feed on.

## Segment V: World of Ammonites

***“ They are one of the most successful groups of animals to have ever lived, flourishing in the warm, temperate seas, and even the coldest waters at the poles... ”***

― **David Attenborough**, *Oceans*
TBA

## Segment VI: *Morturneria*

* Kronören and Ormberget-Hertsölandet nature reserves, Sweden
* Breakwater Fort in Dorset, England

**Oceans**, Segment VI
**Setting**
López de Bertodano Formation, James Ross Island, James Ross Archipelago, Antarctica

**Filming Location**

* Kronören and Ormberget-Hertsölandet nature reserves, Sweden
* Breakwater Fort in Dorset, England

The sixth and final segment of Oceans takes place in the frozen seas surrounding Antarctica.

***“ ... like here in the frozen sea around the Antarctic. After a winter of near-total darkness, the low sun is beginning to melt the ice, making it accessible once more for a giant seasonal visitor. ”***

― **David Attenborough**, *Oceans*
After a long, cold winter of almost-total darkness, the low sun shines down for the first time in months, melting and opening up some gaps in the ice.

***“ Morturneria, a strange type of elasmosaur. They are warm-blooded, with a thick layer of blubber which conserves the heat in their body. They're one of the world's most secretive and elusive animals. This pod has migrated nearly two thousand miles from South America to arrive here in time for spring. ”***

― **David Attenborough**, *Oceans*
Emerging from one of these gaps is a *Morturneria* followed by its calf, which snuggles up to its parent. These *Morturneria* are part of a pod that traveled 2000 miles from South America to feast in the Antarctic during spring. Within another ice gap, a small group of four *Morturneria*, are shown resting up for the moment.

***“ It's the first time this year's calves will have encountered sea ice. It can be dangerous for an air-breathing reptile. They can only grab a breath of air where there are gaps in the ice. Adults must navigate carefully to find them, and the youngsters must stay close. ”***

― **David Attenborough**, *Oceans*
One calf dives down under the ice to emerge out of another ice gap just a short distance nearby, where four adult *Morturneria* are waiting.

***“ These cold waters are an excellent habitat for this giant's favorite food. Polar mud, full of small creatures. There can be hundreds of tiny animals in every square foot of seafloor. Separating what's edible from the sticky mud is a challenge. But they have a neat solution. Scooping up a mouthful, they partially close their jaws, creating a giant sieve to filter out the food. These are the only animals to have evolved teeth to feed in this way. ”***

― **David Attenborough**, *Oceans*
Deciding it is now time to feed, the pod of elasmosaurs descend to the depths, scraping their half-closed jaws against the the sea floor (with some sweeping their mouths horizontally across the seabed, and others rushing forward to shovel in a mouthful of it), scooping up the mud and filtering out the hundreds of tiny animals with their sieve-like combs of needle-like teeth. A *Morturneria* calf returns to the surface to briefly take a breath of air, then dives back down to rub against its mother before surfacing with her to breach the surface.

***“ The Morturneria will feed here all summer until the water ices over again in the polar winter. In warmer waters, they will face other challenges, but the most resourceful animals will always find opportunities in the vast oceans of the Prehistoric Planet. ”***

― **David Attenborough**, *Oceans*
The segment ends with the calf swimming around in the ice gap under the watch of its mother as the view zooms out to show the extent of the frozen seas of Antarctica under the light of the low sun.

## Uncovered Segment I: How Fast Was A Mosasaur?

  **How Fast Was A Mosasaur?**
**Subject**
The speed and acceleration of mosasaurs, as well as the means which allow them to perform the feats that make them quick, formidable, and powerful ambush predators.

**Experts**
Dr. Michael Habib, Kiersten Formoso
This Uncovered segment is dedicated to discussing how fast a mosasaur could be.

***“ Mosasaurs were seagoing lizards. Think of a giant, swimming, whale-sized Komodo Dragon. Tapered snout, rough skin, four fins instead of normal limbs, and a long tail that would look a lot like a shark tail, but upside down. That's basically a mosasaur. ”***

― **Dr. Michael Habib**, *University of California*
Presented as the main focus is the largest mosasaur, *Mosasaurus hoffmannii*. The secret to the success of this ambush hunter is that it can move with incredible speed while it was only stationary moments before. Today, this is demonstrated by crocodiles, which have muscles that can deliver short bursts of tremendous power. Dr. Michael Habib, one of the show's consultants, brings up how mosasaurs may have bent themselves in a C-shape, then, in one sudden movement, push off of the water on the side of their bodies. As seen in modern-day fish, this "C-start" technique allows them to accelerate from a standstill to full speed in an instant. The suggestion is that mosasaurs use this same technique on a much greater scale. Using a 42-foot, 12-ton mosasaur for reference, the Prehistoric Planet research team ran a unique test four times to finally figure out exactly how fast can *Mosasaurus hoffmannii* actually swim.

***“ This mosasaur could probably clear 75% of its body length in one single second. That means if that mosasaur is 17 meters away from you, in one second, it will be 75% closer, and in the 2nd second, it would have surpassed you and probably eaten you along the way. ”***

― **Kiersten Formoso**, *University of Southern California*
The force generated by a mosasaur traveling at full speed is compared to the impact of a full-sized semi-truck, which, along with the mosasaur's powerful bite force, can prove immediately fatal.

***“ Mosasaurs could reach 30 miles an hour in as little as one second. This is what makes them arguably the ultimate marine predator of all time. ”***

― **David Attenborough**, *Prehistoric Planet: Uncovered - How Fast Was A Mosasaur?*
With this, based off of these calculations, a mosasaur 13 meters (42 feet) in length like the one in the diagram displayed in this segment could travel 9.75 meters (32 feet) per second, and a mosasaur that is 15 meters (50 feet) long like the one on the show could travel 11.4 meters (37 feet) per second.

## Uncovered Segment II: What Do We Really Know About Ammonites?

  **What Do We Really Know About Ammonites?**
**Subject**
Various facts and knowledge about ammonites.

**Experts**
Dr. Darren Naish, Zoe Hughes
TBA

## Fauna

*Mosasaurus hobetsuensis**Phosphorosaurus ponpetelegans**Hesperornis regalis**Xiphactinus audax**Nostoceras sp.**Pyroraptor olympius**Tuarangisaurus keyesi**Mosasaurus hoffmannii**Baculites sp.**Diplomoceras maximum**Sphenodiscus sp.**Morturneria seymourensis*
## Trivia

### Filming Locations

Filming locations for the episode were confirmed on "I Know Dino: The Big Dinosaur Podcast", Episode 446: Dinosaur-era Oceans and Darren Naish from Prehistoric Planet 2.

* The first and fourth segments (set in the Hakobuchi Formation in Hokkaido, Japan and what is likely the Tahora Formation in New Zealand, respectively) were shot in a reef by Grand Cayman Island, and in an underwater studio.
* The second segment, set in the the Western Interior Seaway, was shot in Dunsborough, Western Australia.
* The third segment, set on the Ibero-Armorican Island (which encompasses France and the Iberian Peninsula), was shot at Porto Santo Island near Madeira, Portugal.
* The fifth segment, set in the Tethys Ocean, was shot in the Es Freus Marine Reserve in the Mediterranean Sea near Ibiza, Spain.
* The sixth and final segment, set in the López de Bertodano Formation in Antarctica, was shot in the Kronören and Ormberget-Hertsölandet nature reserves in Sweden, and at Breakwater Fort in Dorset, England.

### Scrapped Content

* The second segment of the episode was supposed to feature unidentified diving pterosaurs being among the predators feasting on the massive bait ball. More importantly, the schools of fish are forced into a bait ball by a pod of *Hydrotherosaurus*, 8-meter (26-foot) elasmosaurs that weigh 1.1 metric tons (2.2 short tons), and possess a 4-meter (13-foot) neck with 60 vertebrae, almost half as long as the longest neck of any plesiosaur, *Albertonectes*, which has an 8-meter (26-foot) neck with 76 vertebrae.
* The polycotylid *Dolichorhynchops* was also planned to be featured alongside *Hesperornis* according to concept art for the second segment of the episode.
	+ Polycotylids have previously been planned for Prehistoric Planet, as Dr. Darren Naish, the show's lead consultant, once revealed that there was a conceptualized scene for the first season involving polycotylids threatened by an underwater earthquake.
* While the second segment of this episode is meant to take place in the Western Interior Seaway during the early Maastrichtian stage of the Late Cretaceous Period (around 72 million years ago), its exact setting remains unknown. Based on the presence of the scrapped animals, the segment could be, at least during the planning stages, either within or near the Moreno Formation in San Joaquin County, California, USA (where *Hydrotherosaurus* is known from) or the Pierre Shale, a formation in the Great Plains, east of the Rocky Mountains, stretching from Pembina Valley in Canada to New Mexico (where the last and largest species of *Dolichorhynchops*, *D. bonneri*, is known from).

## References

1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 I Know Dino: The Big Dinosaur Podcast, Episode 446: Dinosaur-era Oceans and Darren Naish from Prehistoric Planet 2
2. ↑ Seguillon, Gaëlle on Artstation, revealing concept art for the second segment of Oceans featuring *Hydrotherosaurus* and an unknown species of diving pterosaur
3. ↑ Ugueto, Gabriel (@SerpenIllus) (May 25, 2023) on Twitter, revealing *Hesperornis* concept art featuring *Dolichorhynchops* in the background
4. ↑ Naish, Darren (@TetZoo) (May 30, 2022) on Twitter, revealing an unmade scene involving polycotylids threatened by seismic activity in the deep sea