Dino card No. 0796 of 2,015

Hesperornis

Say it: HESS-per-OR-nis

Name means: “western bird”1

Ate: FishEarly birdsLate Cretaceous

Hesperornis was a giant swimming bird that lived in the time of dinosaurs. It had teeth in its beak and could not fly, but it was a super diver in the ancient seas.1 2

Lived

90 to 66 million years ago3

Late Cretaceous

Fossils found in

North America (Kansas, Montana, South Dakota, Alaska, Canada), Russia, and Sweden3 1

Food

Fish3 2

Length

1.5 to 1.8 m1

estimate for the largest species

Artist's life restoration of Hesperornis — How Hesperornis may have looked, by TotalDino. CC BY-SA 4.0, via Wikimedia Commons. Scientists still argue about colours and details.

When did it live?

Triassic

Jurassic

Cretaceous

252 million years ago20114566, the asteroid

How big was it?

cool stuff

Fun facts

Hesperornis was one of the first birds to give up flying and become a full-time swimmer.2

Its legs were placed far back on its body, like a loon, making it clumsy on land but a powerful diver.1

Hesperornis had teeth in its beak, which is rare for birds. It used them to catch fish.1 2

The first fossils of Hesperornis were found by famous fossil hunter Othniel Charles Marsh in 1870 in Kansas.1 2

Several species of Hesperornis lived from about 90 to 66 million years ago, during the Late Cretaceous.3

Hesperornis fossils have been found in many places, including Canada, the United States, Russia, and Sweden.3

Myth buster

Myth: Some people think Hesperornis was a dinosaur.

Truth: Hesperornis was a bird, not a dinosaur. Birds evolved from dinosaurs, but Hesperornis itself is classified as a bird.1

For dino experts

Scientific name: Hesperornis
Named by: Marsh 18723
Group: Early birds
Family / clade: Hesperornithidae3
Classification: Theropoda > Avialae3
Age of the rocks: 90 to 66 million years (Coniacian to Maastrichtian)3
Rock formations: Pierre Shale, Rybushka, Niobrara3
Countries: Canada, USA, Russia, Sweden3
Fossil records: 65 in the Paleobiology Database3
Also known as: Coniornis, Hargeria, Lestornis (older names now counted as the same animal)3
Discovery: Othniel Charles Marsh discovered the first Hesperornis fossil in 1870 near the Smoky Hill River in Kansas. He named it Hesperornis regalis in 1872.1 2
Still debated: Scientists are still debating exactly how many species of Hesperornis existed, because many fossils are incomplete.1

Where the facts come from

Hesperornis (en.wikipedia.org)
The Hesperornithiformes: A Review of the Diversity, Distribution, and Ecology of the Earliest Diving Birds (mdpi.com)
Hesperornis in The Paleobiology Database (CC BY 4.0): age, places, rock formations, classification.

Every fact on this page has a number that points to its source. If we got something wrong, sorry, we are dino fans, not a science journal. Tell us at [email protected] and we will fix it.