Difference Between Brontosaurus and Brachiosaurus

The main difference between Brontosaurus and Brachiosaurus is that the Brontosaurus was a quadruped dinosaur with a loud, rumbling noise whereas the Brachiosaurus was a gigantic dinosaur with disproportionately long neck, small skull, and large overall size. Furthermore, Brontosaurus is known as ‘thunder lizard’ while Brachiosaurus is known as ‘arm lizard’.

Brontosaurus and Brachiosaurus are two genera of sauropod dinosaurs that lived during the Late Jurassic period. 

Key Areas Covered 

1. Brontosaurus
     – Definition, Characteristics, Behavior
2. Brachiosaurus
     – Definition, Characteristics, Behavior
3. What are the Similarities Between Brontosaurus and Brachiosaurus
     – Outline of Common Features
4. What is the Difference Between Brontosaurus and Brachiosaurus
     – Comparison of Key Differences

Key Terms 

Arm Lizard, Brachiosaurus, Brontosaurus, Forelimbs, Late Jurassic Period, Sauropod, Thunder Lizard

Difference Between Brontosaurus and Brachiosaurus - Comparison Summary

Brontosaurus – Definition, Characteristics, Behavior 

Brontosaurus was a herbivorous dinosaur that lived 150 million years ago during the Late Jurassic period in the western part of the Northern hemisphere. It was first discovered by Othniel Charles Marsh in 1879. Its remains were found in Utah, Wyoming, and Mexico. Brontosaurus had a long neck, counterbalanced by a long tail, which was used as a weapon. It could produce a sound of 200 decibels (louder than the firing of a cannon) by cracking their tail like a bullwhip. Thereby, Brontosaurus is also called ‘thunder lizard’.  

Difference Between Brontosaurus and Brachiosaurus_Figure 01

Figure 1: Brontosaurus excelsus

The genus Brontosaurus contains three species: B. excelsusB. yahnahpin, and B. parvus. In addition, Apatosaurus is a closely-related genus to the B. excelsus species.  

Brachiosaurus – Definition, Characteristics, Behavior 

Brachiosaurus is a gigantic, herbivorous dinosaur that lived 155.7-150.8 million years ago during the mid- to Late Jurassic period in North America, Africa, and Tanzania. It was first discovered by Elmer S. Riggs in 1903 in Western Colorado. The main characteristic features of a Brachiosaurus are the long neck and the short hind legs. Hence, it is called the ‘arm lizard’. Also, Brachiosaurus was giant compared to the Brontosaurus.  

Difference Between Brontosaurus and Brachiosaurus_Figure 02

Figure 2: Brachiosaurus altithorax

Brachiosaurus was originally considered the largest dinosaur ever on the earth. The weight of a Brachiosaurus is equal to the weight of four elephants. But, other sauropods were found later that were heavier than Brachiosaurus.  

Similarities Between Brontosaurus and Brachiosaurus 

  • Brontosaurus and Brachiosaurus are two types of sauropod dinosaurs. 
  • They belong to the order Saurischia. 
  • They lived 150 million years ago in the Late Jurassic period, which is the third epoch of the Jurassic period. 
  • These dinosaurs first appeared in the Late Triassic and resembled Prosauropoda.  
  • Both were warm-blooded animals. Their enormous size helped them to keep high body temperatures around 38.2 C. Hence, dinosaurs are called gigantotherms. 
  • They had very long necks, long tails, and small heads relative to the rest of their body, and four thick, pillar-like legs. 
  • Their hind legs were thick, straight, and powerful and had five toes. Inner three toes had claws.  
  • Their forelimbs are slender and supported the weight. Only the thumb has claws. 
  • They were herbivores. 
  • Both these dinosaurs were replaced by titanosaurs by the Late Cretaceous period. 

Difference Between Brontosaurus and Brachiosaurus 


Brontosaurus refers to a huge herbivorous dinosaur of the late Jurassic period, with a long neck and tail while Brachiosaurus refers to a huge herbivorous dinosaur of the late Jurassic to Mid-Cretaceous periods, with forelegs much longer than the hind legs. 

Also Known as 

Thunder lizard is another name for Brontosaurus while Brachiosaurus is also called arm lizard. 


When comparing the sizes of these two dinosaurs, Brachiosaurus was bigger Brontosaurus. Brontosaurus weighed up to 15 tons while Brachiosaurus weighed more than 55 metric tons. In addition, the length of a Brontosaurus is estimated as 72 feet while the length of a Brachiosaurus is estimated as 85 feet.  


While Brontosaurus had short forelimbs compared to their hind legs, Brachiosaurus had long forelimbs compared to their hind legs. 

Feeding Habits 

Although both these dinosaurs are herbivores, their feeding habits are somewhat different. Brontosaurus ate low plants while Brachiosaurus grazed high canopies of trees. 


Brontosaurus lived in the western part of the Northern hemisphere while Brachiosaurus was widely distributed around the world with a high population number.


Brontosaurus was a comparatively small dinosaur with short forelimbs while Brachiosaurus was a giant dinosaur with long forelimbs. Furthermore, Brontosaurus refers to the thunder lizard while Brachiosaurus refers to the arm lizard. Both of them are sauropods lived in the Late Jurassic period. The main difference between Brontosaurus and Brachiosaurus is the size and the length of the forelimbs.


1. “Brontosaurus – Facts and Pictures.” Dinosaurs – Pictures and Facts, 5 Oct. 2017, Available Here
2. Castro, Joseph. “Brachiosaurus: Facts About the Giraffe-like Dinosaur.” LiveScience, Purch, 16 Mar. 2016, Available Here

Image Courtesy:

1. “Brontosaurus by Tom Parker” By Tom Parker – Own work (CC BY-SA 4.0) via Commons Wikimedia   
2. “Brachiosaurus DB” By Богданов [email protected] – Own work (Public Domain) via Commons Wikimedia

About the Author: Lakna

Lakna, a graduate in Molecular Biology and Biochemistry, is a Molecular Biologist and has a broad and keen interest in the discovery of nature related things. She has a keen interest in writing articles regarding science.

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