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Monoclonius

Say it: mon-oh-KLOH-nee-us

Name means: “single sprout”1

Ate: PlantsHorned dinosLate Cretaceous

Monoclonius was a plant-eating dinosaur with a big frill on its head and a horn on its nose. It lived about 75 million years ago in what is now Montana and Alberta. Scientists are not sure if Monoclonius is really its own dinosaur or just a young version of another dinosaur called Centrosaurus.1 2

Lived

84 to 72 million years ago5

Late Cretaceous

Fossils found in

Montana, USA and Alberta, Canada1 2

Food

Plants2

Length

4.5 to 5.5 m1

estimate based on related ceratopsians

Weight

1.8336 tonnes to 2.17 tonnes3 4

estimates from different sources

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 1.5 cars

as long as 6 dogs nose to tailas long as 31 bananas end to endas heavy as 72 big dogsas heavy as 430 watermelons

How big was Monoclonius compared to YOU?

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cool stuff

Fun facts

Monoclonius was named in 1876 by the famous fossil hunter Edward Drinker Cope, just months after the Battle of the Little Bighorn.1

The name Monoclonius means 'single sprout' and refers to how its teeth grew, not to a horn. Cope thought only one set of teeth was used at a time.1

Many fossils once called Monoclonius are now thought to belong to other dinosaurs, like Centrosaurus or Styracosaurus.1

The type species is Monoclonius crassus, which means 'the fat one' in Latin.1

Monoclonius fossils have been found in the Judith River Formation in Montana and the Dinosaur Park Formation in Alberta.1 2

When Cope first described Monoclonius, he did not realize it was a horned dinosaur. He thought the skull frill was part of the breastbone.1

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

?How big was Monoclonius?

Monoclonius was up to 5 metres (16.5 feet) long and may have weighed about 2,170 kilograms (4,780 pounds).4

?What did Monoclonius eat?

Monoclonius was an herbivore, a plant eater. It probably ate cycads, palms, and other prehistoric plants with its tough, hook-like beak.4

?When did Monoclonius live?

Monoclonius lived in the Late Cretaceous period, about 76 to 73 million years ago, toward the end of the age of dinosaurs.4

?Why is Monoclonius called a nomen dubium?

Monoclonius is often considered a nomen dubium, or doubtful name, because the fossils are too incomplete or immature to be confidently matched with adult specimens. Many are thought to be young Centrosaurus.1

?Did Monoclonius have a horn on its nose?

Yes, Monoclonius had a single nose horn that pointed upwards and two smaller horns over its eyes, plus a small frill on its head.4

?Where were Monoclonius fossils found?

Monoclonius fossils have been found in Montana, USA, and Alberta, Canada.4

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Myth buster

Myth: Monoclonius means 'single horn'.

Truth: Monoclonius actually means 'single sprout', referring to its teeth, not a horn. Cope named it before he knew it was a horned dinosaur.1

For dino experts

Scientific name: Monoclonius
Named by: Cope 18765
Group: Horned dinos
Family / clade: Ceratopsidae5
Classification: Ornithischia > Ceratopsia > Ceratopsidae5
Age of the rocks: 84 to 72 million years (Campanian)5
Rock formations: Oldman, Judith River, Kirtland5
Countries: USA, Canada5
Fossil records: 13 in the Paleobiology Database5
Discovery: Edward Drinker Cope named Monoclonius in 1876 based on fossils found near the Judith River in Montana by himself and a young Charles Sternberg.1
Still debated: Scientists debate whether Monoclonius is a valid genus or just a mix of juvenile Centrosaurus and other ceratopsids. Many consider it a nomen dubium (doubtful name).1 2

Where the facts come from

Monoclonius (en.wikipedia.org)
PBDB Taxon (paleobiodb.org)
Monoclonius Cope 1876 - Encyclopedia of Life (eol.org)
enchantedlearning.com (enchantedlearning.com)
Monoclonius in The Paleobiology Database (CC BY 4.0): age, places, rock formations, classification.

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