Hesperornis

## HesperornisWestern Bird

### Temporal Range

83.6 - 72 million years ago, Campanian - Maastrichtian Stage, Late Cretaceous Period

## Characteristics

### Diet

Carnivore

***“ 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. And they are a magnet for 6 foot-long Hesperornis. ”***

― **David Attenborough**, *Oceans*
***Hesperornis*** (Western Bird) is a genus of cormorant-like bird that lived in North America and Russia, 83.6 - 72 million years ago, during the Campanian stage of the Late Cretaceous Period. Remains found in Canada indicate that *Hesperornis* may have lived up to the early Maastrichtian stage of the Late Cretaceous Period.

## Description

### Size and Physique

***“ Hesperornis may be unable to fly, but it's superbly adapted to ocean life. Large, powerful feet propel it with great agility. ”***

― **David Attenborough**, *Oceans*
*Hesperornis* was a large seabird that reached up to 1.8 meters (6 feet) in length. It is virtually wingless, but it makes up for with its streamlined body and powerful hind legs that helped it swim quickly.

Hesperornithiform toes are believed to be lobed much like modern-day grebes, hence, Prehistoric Planet depicts *Hesperornis* with lobed feet. However, due to more recent studies, webbed toes for hesperornithiforms is just as likely as lobed toes.

### Dentition

***“ There's no escape for any unfortunate fish once it's caught by this beak, full of needle-sharp teeth. ”***

― **David Attenborough**, *Oceans*
Like many other Mesozoic birds, *Hesperornis* had teeth in its hooked, keratinous beak, fit for gripping fish. However, compared to other birds, the teeth of hesperornithiform birds are placed in longitudinal grooves rather than individual sockets, much like the thousand of bristle-like set of teeth on the lower jaw of the filter-feeding pterosaur *Pterodaustro*. Its palate (mouth roof) had small pits for the teeth of the lower jaw to fit in when the mouth is closed. *Hesperornis* matured fairly quickly.

### Prehistoric Planet's Depiction

Prehistoric Planet depicts *Hesperornis* with feathers in white, gray, and black tones, providing it with a countershaded coat. Most animals, predator and prey alike, are known to rely on countershading to effectively camouflage themselves, blending in with darkness when seen from above, and blending in with light when seen from below. The coat of *Hesperornis* is very much like those of puffins, penguins, and even sharks, which come in dark grays and blacks opposite their white or light gray undersides. *Hesperornis* does have some accents on its coat in the form of whitish speckles on its back along with white eyebrows and cheeks. Its yellow-orange eyes, beak, and throat also further stand out from its black, white, and gray appearance.

## Habitat

*Main: Western Interior Seaway*

Main: Western Interior Seaway

Eight *Hesperornis* species are known from North America, but one species, *Hesperornis rossicus*, was also found in Russia.

## Behavior

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

― **David Attenborough**, *Oceans*
Similar to penguins, *Hesperornis* is capable of remaining submerged in the sea for extended periods of time to hunt for fish. This ability allows them to be efficient and agile hunters. When faced with predators like *Xiphactinus*, Hesperornis relies on its speed and acrobatic maneuvers to evade and escape their pursuers.

## Appearance

### Oceans

The second segment of Oceans focuses on what happens during the day in the warm, shallow seas of North America. A massive shoal of fish attracts many *Hesperornis*, the flightless seabirds catching several fish with their beaks full of needle-sharp teeth. This great gathering of fish also attracts several *Xiphactinus*, which swallow mouthfuls of fish 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*
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. 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 on the menu. With the shoal of fish reduced to nothing, the banquet is over, and the predators move on.

## References

1. ↑ *Hesperornis* (Aves) from Ellesmere Island and palynological correlation of known Canadian localities
2. ↑ *Colymbus*, *Hesperornis*, *Podiceps*: ein Vergleich ihrer hinteren Extremität
3. ↑ Morphometric comparison of the Hesperornithiformes and modern diving birds
4. ↑ Elzanowski, A. (1991). "New observations on the skull of *Hesperornis* with reconstructions of the bony palate and otic region". Postilla. 207: 1–20.
5. ↑ Bone microstructure of the diving *Hesperornis* and the volant *Ichthyornis* from the Niobrara Chalk of western Kansas