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Siats

Say it: see-ATS

Name means: “Named after Siats, a man-eating monster from Ute Native American legends.”1 2

Ate: MeatMeat-eating dinosLate Cretaceous

Siats was a giant meat-eating dinosaur that lived in North America about 98 million years ago. It was one of the biggest predators of its time, and it may have hunted plant-eating dinosaurs like Eolambia.1 2

Lived

100 to 94 million years ago5

Late Cretaceous

Fossils found in

Fossils were found in the Cedar Mountain Formation in Utah, USA.1 5

Food

Meat5 2

Length

10 m3

Weight

3.9 tonnes1

When did it live?

Triassic

Jurassic

Cretaceous

252 million years ago20114566, the asteroid

How big was it?

How long was it?

How heavy was it?

as heavy as 2.5 cars

as long as 2 cars parked in a rowas long as 56 bananas end to endas heavy as 130 big dogsas heavy as 780 watermelons

How big was Siats compared to YOU?

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

cool stuff

Fun facts

Siats was one of the largest predators in North America during the early Late Cretaceous, weighing about 3.9 metric tons (4.3 short tons).1

The only known Siats skeleton is from a young animal, not a fully grown adult, so it might have been even bigger.1 2

Siats lived at the same time and place as small tyrannosauroids, and scientists think it may have kept them from growing huge.2

The name Siats comes from a man-eating monster in Ute tribal legends from Utah.1 2

Siats is the first megaraptoran dinosaur ever found in North America.2

The fossil bones were found sticking out of a hillside during a 2008 expedition.1

AI-made picture of Siats — An AI-made picture of how Siats 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 Siats

?How big was Siats?

Siats was about 10 metres (33 feet) long and weighed around 3.9 metric tons (4.3 short tons). That is as heavy as two large cars.1 4

?What did Siats eat?

Siats was a meat-eater that probably hunted plant-eating dinosaurs like Eolambia. It was the top predator of its time.2 4

?Was Siats bigger than T. rex?

No, Siats was smaller than T. rex. T. rex could be over 12 metres (40 feet) long and weigh more than 8 metric tons, while Siats was about 10 metres (33 feet) long and weighed about 4 metric tons.1 4

?When did Siats live?

Siats lived about 98 million years ago, during the early Late Cretaceous period. That is about 30 million years before T. rex appeared.1 2

?Where was Siats found?

Siats was found in Utah, USA, in the Cedar Mountain Formation. Its bones were first seen sticking out of a hillside in 2008.1 4

?Is Siats a dinosaur?

Yes, Siats is a dinosaur. It is a large meat-eating theropod dinosaur, not a pterosaur or marine reptile.1 5

Ask Rex about Siats

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Myth buster

Myth: Some people think Siats was a tyrannosaur, like T. rex.

Truth: Scientists think Siats was an allosauroid, a different group of meat-eaters, not a tyrannosaur.1 2

For dino experts

Scientific name: Siats
Named by: Zanno and Makovicky 20135
Group: Meat-eating dinos
Family / clade: Megaraptora5
Classification: Theropoda > Megaraptora5
Age of the rocks: 100 to 94 million years (Cenomanian)5
Rock formations: Cedar Mountain5
Countries: USA5
Fossil records: 1 in the Paleobiology Database5
Discovery: Siats was discovered by Lindsay Zanno during a 2008 Field Museum expedition with Peter Makovicky. The bones were collected from 2008 to 2010 in Utah, and the dinosaur was named in 2013.1
Still debated: Scientists are not sure exactly where Siats belongs in the dinosaur family tree. Some think it was a megaraptoran, while others suggest it was closer to tyrannosaurs.1

Where the facts come from

Siats (en.wikipedia.org)
Neovenatorid theropods are apex predators in the Late Cretaceous of North America | Nature Communications (nature.com)
Siats (en.wikipedia.org)
Dominant Dinosaur That Lived Before T. rex Discovered - Field Museum (fieldmuseum.org)
Siats 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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