These birds are called Hesperornis. They are so vociferous it's deafening being right in the middle of a colony. They're flightless like penguins but they're far from as cute.
— Allen, on Hesperornis

Hesperornis (name meaning "Western Bird") is a genus of large penguin-like bird that originated during the Late Cretaceous period in what is now North America and Asia. Due to its design, this aquatic, flightless creature was cumbersome on land but was a fabulous swimmer.

In the Series 2 finale "Fall of a Kingdom Part I: Hell's Aquarium", a large number of Hesperornis was brought back to the park from the Late Cretaceous 65 million years ago. They reside in the Primeval Aquarium exhibit.


Era & DiscoveryEdit

Hesperornis lived during the Late Cretaceous period 85-65 million years ago. The first Hesperornis specimen was discovered in 1871 by Othniel Charles Marsh.

Physical AttributesEdit

A species of Cretaceous sea birds that measured over 6 feet (2 m) long and looked similar to penguins, Hesperornis was a large, flightless seabird. It had black feathers, small red legs, a long, stalk-like neck, a long red-colored head with a golden, dagger-like beak lined with needle-sharp teeth, and its toes were flat and clawless.

Due to the fact that its legs were positioned too far down its body, almost along the tail, and its wings were too small to provide counterbalance Hesperornis couldn't fly like other birds do and couldn't move efficiently on land or even stand upright, but rather crawled around, like modern loons and grebes do. However, just like the modern loons and grebes, once underwater, Hesperornis was agile and maneuverable. It swam as modern penguins do, able to accelerate and make sharp turns, perfect for underwater hunting. They were perfectly adapted for diving, with especially heavy bones to help them stay submerged. Unfortunately, during the Cretaceous, the seas were far more dangerous than the land.

Despite its size, it had many predators, like the giant fish Xiphactinus, the shark Squalicorax, the Halisaurus or even Tylosaurus, the top predator of that time.

Behavior & TraitsEdit

Surprisingly, Hesperornis lived in large colonies that would spend most of their time basking on the seashore. In these groups, they were extremely vociferous. They were so vociferous, it would be deafening being in the middle of a colony.

Like penguins, Hesperornis were flightless. However, they were far from being as adorable. They hunted fish on the seas and they used the beaches as refuges from the predators. But just to hold their own, Hesperornis had to be tough. They were around a time where there were truly awe-inspiring predators. Hesperornis spent most of their lives in water.

But few Hesperornis lived to a ripe old age, because where they’re from, there were so many ways to get eaten: they were common prey for many other sea creatures, such as sharks, fish like Xiphactinus, and mosasaurs like Tylosaurus. In its turn, Hesperornis feed on fish and squid that it caught with its toothy beak. On the shore, they were at risk of attack by predatory dinosaurs, like Tyrannosaurus.

Prehistoric Earth: A Natural History Edit

Series 2 Edit

In the second to last episode of Series 2, dozens of Hesperornis were brought to the park. They reside in the Marine Exhibit.



  • The sound effects of Hesperornis are that of donkey, duck, flamingo, geese, penguin, sea lion, seal, and walrus sound effects.
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