Prehistoric Planet S 1 E 1 Coasts / Recap

Creatures that live in or around the oceans of the Maastrichtian are featured.

Recurring tropes

Eats Babies: The Mosasaurus from the T. rex segment and the Barbaridactylus and Phosphatodraco from the pterosaur segment. The Kaikaifilu from the Tuarangisaurus segment is also implied to have such intentions, given it going after the mother while she's pregnant.
Malicious Monitor Lizard: Downplayed as at the end of the day they are simply predators following their instincts, but mosasaurs (relatives of monitor lizards) play an antagonistic role in all of the segments where they appear: one eats a baby T. rex at the beginning of the episode; a younger male starts a fight for territory against the main, older male we follow in the Mosasaurus segment; and a Kaikaifilu attacks the pregnant mother Tuarangisaurus at the climax of the episode.

The Dreaded: The father T.rex is formidable enough that even a giant mosasaur twice its size thinks carefully if attacking him (in its own element no less) is a good idea. The marine reptile decides then going for one of the smaller and thus more vulnerable chicks instead.
Establishing Series Moment: The first shot in the episode is a father T. rex and his offspring swimming across the ocean, establishing that this is not a typical pop-culture portrayal of dinosaurs.
Monster Munch: The giant sea turtles who appear in the segment serve little purpose beyond being a more exotic snack for the T. rex.
Papa Wolf: Played with; the father T. rex is willing to protect his offspring from a Mosasaurus, but when one of them doesn't make it, he seems largely indifferent.
Sea Monster: The Hell Creek mosasaur is portrayed as one unlike the Hoffman's mosasaur later in the episode. It is completely dehumanized, portrayed as a big sea predator who stalks the Tyrannosaurus father and his children and it always remain shadowed or shown from a distance in a way it makes it looks more ominous.

Fantastic Fauna Counterpart: The nesting habits of the Alcione bring to mind sea turtles, as the eggs are laid safely in places that are hard to be accessed by predators and once the hatchlings are born they have to take a dangerous journey to a safer location in which multiple predators await for them.
Giant Flyer: Downplayed; all of the animals in this segment are large creatures capable of flight(most notably Phosphatodraco, who's stated to be nine feet tall), but only two species are actually shown flying and one of them is a flock of babies. The rest are resting on the beaches.
Secondary Sexual Characteristics: The male Tethydraco are larger than the females and have longer crests and beaks.

Behemoth Battle: Between the old Mosasaurus and his young rival. It ends with the rival retreating and the older male victorious.
Old Master: The protagonist of this segment is an old male Mosasaurus who was challenged by a younger one. He's quick to show the young upstart that experience matters.
Sea Monster: Played with. The Mosasaurus is depicted in a more peaceful light here, simply getting a nice scrubbing from symbiotic fish and shrimp... then he's suddenly attacked by a rival male and a Behemoth Battle ensues.

Eat Dirt, Cheap: The Tuarangisaurus swallow stones, partly to keep from being too buoyant and partly to grind up their food since they can't chew.

Bioluminescence Is Cool: The scaphitid ammonites have bioluminescence that they usually use to attract prey, but here they use them to attract mates.
Bittersweet Ending: The scaphitids all die after they mate, but they have ensured that a new generation will be born.
Out with a Bang: The scaphitids die after mating.
Secondary Sexual Characteristics: The female scaphitids are larger than the males.

Imperiled in Pregnancy: The mother Tuarangisaurus is attacked by a hungry Kaikaifilu while pregnant with her second baby. Fortunately, her older offspring and the rest of their pod help fend it off.