'Brontosaurus' vs 'Brachiosaurus': What's the Difference?

By Amy Gilmore, updated on October 10, 2023

Are you curious about the difference between 'brontosaurus' vs. 'brachiosaurus?' I can help!

Here is a summary: 

  • A 'Brontosaurus' was a large dinosaur belonging to the Sauropoda suborder, which has shorter front legs than forelegs. 
  • A 'Brachiosaurus' was a huge dinosaur belonging to the Sauropoda suborder, which had longer front legs.  

The above answer is an overview. There is much more to learn about these two dinosaurs, which people often mix up. So, read this entire post to learn exactly how they differ.

What is the Difference Between a 'Brontosaurus' vs. 'Brachiosaurus?'

The 'Brontosaurus' and 'Brachiosaurus' are both herbivores, which means they ate plants. Both had stalky bodies with long necks and small heads, and both had whip-like tails. So, people often confuse them.

However, the 'Brontosaurus' was a smaller dinosaur, measuring a maximum of 28 feet tall, and the 'Brachiosaurus' was nearly 12 feet taller at a maximum height of 40 feet.

  • The 'Brontosaurus' was slightly longer at 72 to 85 feet long, but it weighed significantly less at 67,000 lbs than the larger 'Brachiosaurus' which grew to a maximum length of 72 feet and weighed as much as 128,000 lbs.

Another significant difference was their body structure. A 'Brontosaurus' had shorter front legs because it ate food at the ground level, while the 'Brachiosaurus' ate leaves from the tree canopy.

Definition of 'Brontosaurus': What Does 'Brontosaurus' Mean?

According to the Merriam-Webster Dictionary, 'Brontosaurus' is a noun that means:

  • Any dinosaur belonging to the Apatosaurus genus of Sauropod dinosaurs, which were characterized by their shorter forelegs and longer hind legs

The dictionary includes a note stating that people continue to use the Brontosaurus name despite the genus being found invalid. However, that information is now outdated.

In the late 19th century, a scientist classified the huge dinosaur as a member of the Apatosaurus genus. However, in 2015, scientists discovered that the giant should be classified as its own subgenus of the Sauropod family of dinosaurs.

Definition of 'Brachiosaurus': What Does 'Brachiosaurus' Mean?

The same defines the noun 'Brachiosaurus' as:

  • A huge dinosaur belonging to the Sauropoda subfamily, which is characterized by having longer front legs than hind legs

Other Dinosaurs of the Late Jurassic Period

Below is a list of other dinosaurs that likely lived during the same period as the 'Brontosaurus' and 'Brachiosaurus.'

  • Stegosaurus
  • Diplodocus
  • Triceratops
  • Ankylosaurus
  • Sauropoda
  • Iguanadon
  • Protoceratops
  • Giraffatitan
  • Pachycephalosaurus
  • Tyrannosaurus
  • Alamosaurus
  • Parasaurolophus
  • Edmontosaurus
  • Ouranosaurus
  • Gargoyleosaurus
  • Omeisaurus
  • Parkosaurus
  • Vulcanodon
  • Kentrosaurus
  • Aardonyx
  • Avaceratops
  • Pachyrhinosaurus
  • Saltasaurus
  • Atlascopcosaurus
  • Agilisaurus
  • Centrosaurus
  • Euoplocephalus
  • Achelousaurus
  • Hadrosaurus
  • Styracosaurus
  • Nodosaurus

Pronunciation: How to Pronounce 'Brontosaurus' vs. 'Brachiosaurus'

Learning to pronounce these terms is important if you want to use them in conversation. But learning the correct way to pronounce these dinosaur names should also help you remember the difference between them.

So, here is a pronunciation guide you can follow for 'Brontosaurus' vs. 'Brachiosaurus.'

  • Use this phonetic spelling to pronounce 'Brontosaurus':


  • Use this phonetic spelling to pronounce 'Brachiosaurus':


When to Use 'Brontosaurus' vs. 'Brachiosaurus'

In addition to knowing the difference between these dinosaurs, it helps to know when to use 'Brontosaurus' vs. 'Brachiosaurus.' So, here are some tips:

  • Use 'Brontosaurus' to describe the shorter, longer dinosaur from the late Jurassic period.

As an example, you might say:

The Brontosaurus was recognizable by its shorter forelegs and longer body. 

  • Use 'Brachiosaurus' to describe the taller, heavier herbivore from the late Jurassic period.

For example, you could say:

A 'Brachiosaurus' was an enormous dinosaur that forged for leaves from the tree canopy. 

  • Use 'Brontosaurus' to describe the herbivore with shorter front legs and longer hind legs.

So, you might say:

The Brontosaurus had the perfect body for eating leaves at the ground level. 

  • Use 'Brachiosaurus' and 'Brontosaurus' to differentiate the two from other dinosaurs in the Sauropoda suborder of herbivores.

For example, you can say:

The Brachiosaurus and Brontosaurus both belong to the Sauropoda suborder of dinosaurs, which lived during the Jurassic period. 

  • Use 'Brachiosaurus' to refer to the larger of these two dinosaurs.

So, you could say:

The Brachiosaurus was bigger than the Brontosaurus but smaller than some other Sauropods.

Sample Sentences Using 'Brontosaurus' vs. 'Brachiosaurus'

Now, look at these example sentences using 'Brontosaurus' vs. 'Brachiosaurus.' Reading them should help you remember the difference and learn more ways to use each.


  • The Brontosaurus lived in areas that alternated from wet to dry depending on the season.
  • The long, skinny, giraffe-like neck of the Brontosaurus was perfect for picking up vegetation on and off the ground.
  • Scientists believe Brontosauruses may have been less social than other sauropods, and they might have foraged alone at times.
  • In the late 1800s, a paleontologist mistakenly classified the Brontosaurus as an Apatosaurus. Only recently, in 2015, did scientists discover that the Brontosaurus is in fact a separate classification with unique features.


  • The Brachiosaurus was a herd animal that socialized, lived, ate, and traveled with other Brachiosauruses.
  • Can you imagine seeing a Brachiosaurus eating leaves from a canopy of trees more than 40 feet above the ground?
  • The Brachiosaurus had an enormous tail it could use to defend itself from predators. However, despite its enormous size, it was relatively peaceful.
  • Brachiosauruses stood 40 feet tall and 72 feet long, and their stature made it impossible for them to run from predators.
  • Luckily, the size of the 128,000 lb Brachiosaurus meant that few enemies attempted to prey on it.


  • The Brontosaurus is like the Brachiosaurus' little cousin. They look alike, but the latter was significantly taller and nearly three times heavier.
  • The paleontologist made two significant discoveries during his career. The first was the discovery of a complete Brontosaurus skeleton, and the second was the unearthing of a herd of Brachiosauruses.
  • It is difficult to imagine that the enormous Brachiosaurus and giant Brontosaurus were herbivores. Their entire diet consisted of green leaves and vegetation.
  • Scientists speculate that Brontosauruses and Brachiosauruses ate between 400 and 900 lbs of food daily.

Recap: 'Brontosaurus' vs. 'Brachiosaurus'

Wow! We covered a ton of information about these giant dinosaurs. So, here is a quick review of what you learned about the difference between 'Brontosaurus' vs. 'Brachiosaurus':

  • The 'Brontosaurus' was a slightly smaller Apatosaurus with shorter front legs that reached a maximum height of 38 feet and a maximum length of 85 feet.
  • The 'Brachiosaurus' is a larger Apatosaurus that has longer front legs and reached a maximum height of 40 feet and length of 72 feet. 
  • Despite the 'Brontosaurus' being longer than the 'Brachiosaurus' it was nearly half the nearly half the weight at 67,000 lbs. 

These terms can be confusing even after you know their meaning. After all, experts just discovered after more than 100 years that the 'Brontosaurus' should, in fact, be classified as a Diplodocidae instead of an Apatosaurus.

We encourage you to share this article on Twitter and Facebook. Just click those two links - you'll see why.

It's important to share the news to spread the truth. Most people won't.

Written By:
Amy Gilmore
Amy Gilmore is one of the lead freelance writers for WritingTips.org. She has been a professional writer and editor for the past eight years. She developed a love of language arts and literature in school and decided to become a professional freelance writer after a demanding career in real estate. Amy is constantly learning to become a better writer and loves sharing tips with other writers who want to do the same.

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