Achelousaurus ‭(‬Achelous’s lizard‭)

Achelousaurus ‭(‬Achelous’s lizard‭)
Achelousaurus ‭(‬Achelous’s lizard‭)

Achelousaurus, also known as “‬Achelous’s lizard‭,” was named by paleontologist Scott Sampson in 1995. This herbivorous dinosaur lived during the Late Cretaceous period, approximately 83-70 million years ago. Achelousaurus was a Ceratopsian, estimated 6 meters in length. Achelousaurus fossil remains were found in USA, Montana – Two Medicine Formation, shedding light on the ancient ecosystems of this region and it is offering valuable insights into the prehistoric world and the evolution of Ceratopsian dinosaurs.



Named By

Scott Sampson‭ ‬-‭ ‬1995


Estimated 6 meters long

Type of Dinosaur
Type Species

A.‭ ‬horneri‭ (‬type‭)

When it Lived

Late Cretaceous, 83-70 million years ago

Achelousaurus Facts

While the mighty Tyrannosaurus rex and the colossal Brachiosaurus often steal the spotlight in discussions about dinosaurs, there exists a world of fascinating prehistoric creatures that deserve our attention. Among these lesser-known wonders is Achelousaurus, also known as “Achelous’s lizard.” Discovered in Montana, USA, and hailing from the Late Cretaceous period, Achelousaurus offers a captivating glimpse into ancient ecosystems and the evolution of Ceratopsian dinosaurs.

Named by paleontologist Scott Sampson in 1995, Achelousaurus was a herbivorous dinosaur that roamed the Earth approximately 83-70 million years ago, during the Late Cretaceous period. While it may not have attained the colossal sizes of some of its later relatives, Achelousaurus was a significant member of its ecosystem, and its story is crucial to understanding the evolution of ceratopsian dinosaurs.

Achelousaurus, a member of the Ceratopsia group, was estimated to reach lengths of around 6 meters. Though not as massive as the horned and frilled dinosaurs that followed in later periods, Achelousaurus possessed unique anatomical features. It had a beak-like mouth, used for cropping vegetation, and its frill and horns were not as prominent as those of later ceratopsians. These adaptations offer insights into the dietary preferences and behaviors of this early ceratopsian.

Fossil remains of Achelousaurus were discovered in the USA, specifically in Montana’s Two Medicine Formation. This finding is pivotal in our understanding of the ancient ecosystems of North America during the Late Cretaceous. Achelousaurus’s presence in this region provides valuable clues about the flora and fauna of the time, as well as the environmental conditions that shaped its evolution.

As an herbivorous dinosaur, Achelousaurus likely played a crucial role in the ecosystem as a plant eater. Its unique adaptations offer a window into the dietary habits of early ceratopsians, helping scientists understand the development of these iconic herbivorous dinosaurs.

Achelousaurus offers valuable insights into the early stages of ceratopsian evolution. By studying this dinosaur and its relatives, researchers can better grasp how ceratopsians diversified and adapted over millions of years, eventually giving rise to the well-known horned and frilled dinosaurs of the Late Cretaceous.

Achelousaurus, or “Achelous’s lizard,” may not be as famous as some of its dinosaur counterparts, but its discovery in Montana’s Two Medicine Formation has greatly enriched our knowledge of prehistoric life. This herbivorous dinosaur provides crucial insights into the ancient ecosystems of North America during the Late Cretaceous and the evolutionary journey of ceratopsian dinosaurs.

The story of this enigmatic dinosaur will continue to fascinate and educate us. In the grand narrative of Earth’s history, Achelousaurus serves as a reminder that the world of dinosaurs is vast and diverse, and each discovery brings us closer to unlocking the secrets of our planet’s ancient past.

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