Dino card No. 0802 of 2,027

Hesperornithoides

Say it: HES-per-orn-ITH-oy-deez

Name means: “western bird form”1

Ate: MeatRaptorsLate Jurassic to Early Cretaceous

Hesperornithoides was a small, bird-like dinosaur that lived during the Late Jurassic period. It was a troodontid, a group of smart, fast predators with big brains. This dinosaur was only about as long as a cat, but it was a fierce hunter of insects and small animals.1 4

Lived

155 to 143 million years ago4

Late Jurassic to Early Cretaceous

Fossils found in

Jimbo Quarry, near Douglas, Wyoming, USA1 4

Food

Meat4

Length

0.89 to 1 m1

estimate for the holotype, which may be a subadult or adult

When did it live?

Triassic

Jurassic

Cretaceous

252 million years ago20114566, the asteroid

How big was it?

How long was it?

as long as 2 house cats nose to tailas long as 6 bananas end to end

How big was Hesperornithoides compared to YOU?

Just maths in your browser. Nothing is saved or sent anywhere.

cool stuff

Fun facts

Hesperornithoides was nicknamed 'Lori' before it was officially named in 2019.1

Its skeleton was discovered by accident in 2001 while a field crew was digging up a much larger dinosaur called Supersaurus.1

The fossil was found in a muddy sandstone layer that was once a wetland or lake environment.1

Hesperornithoides lived during the Late Jurassic, about 154 to 143 million years ago, in what is now Wyoming.4

This dinosaur had keratin sheaths on its claws, which are rarely preserved in fossils.1

Hesperornithoides was a troodontid, a group of dinosaurs closely related to birds, and its discovery helped show that bird-like dinosaurs lived much earlier than some scientists thought.1

AI-made picture of Hesperornithoides — An AI-made picture of how Hesperornithoides might have looked, made by a computer from what scientists know. It is a guess: the real animal may have looked different, and nobody knows its true colours.

you asked

Most asked questions about Hesperornithoides

?How big was Hesperornithoides?

About 89 centimetres (35 inches) long, roughly the size of a turkey or a cat.1 2

?Could Hesperornithoides fly?

No. It had wing feathers, but they were too small for flight.3

?What did Hesperornithoides eat?

It was a carnivore that likely hunted insects and small animals.1

?When was Hesperornithoides discovered?

In 2001, by accident while a field crew was digging up a Supersaurus in Wyoming.1 3

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For dino experts

Scientific name: Hesperornithoides
Named by: Hartman et al. 20194
Group: Raptors
Family / clade: Troodontidae4
Classification: Theropoda > Troodontidae4
Age of the rocks: 155 to 143 million years (Kimmeridgian / Tithonian)4
Rock formations: Morrison4
Countries: USA4
Fossil records: 1 in the Paleobiology Database4
Discovery: The skeleton was found in 2001 by a field crew from the Tate Geological Museum led by William Wahl, while they were excavating a Supersaurus. It was named Hesperornithoides miessleri in 2019 by Scott Hartman and colleagues.1
Still debated: Scientists are not sure if the single known specimen was an adult or a subadult, which affects estimates of its full adult size.1

Where the facts come from

Hesperornithoides (en.wikipedia.org)
Hesperornithoides ‘Lori’ Exhibit | Wyoming Dinosaur Center (wyomingdinosaurcenter.org)
Small Wyoming dinosaur helps rewrite the evolutionary story of birds, flight – UW–Madison News (news.wisc.edu)
Hesperornithoides 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.

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