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Brachiosaurus vs. Brontosaurus: 5 Key Differences Explained

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Both Brachiosaurus and Brontosaurus were large herbivorous dinosaurs of the Late Jurassic. They are often confused with each other. This is an easy mistake; they are all characterized by extremely long necks and small heads. So, is it possible to differentiate them? The answer is yes. There are actually a lot of key differences between them.

For starters, they have vastly different shapes and poses, and make a sound louder than a cannon. One is a solitary animal and the other is a social animal. Also, while they are both very large, one is clearly larger than the other. But which one is it? Join us as we learn about these fascinating dinosaurs and discover all their differences.

Comparing Brontosaurus and Brachiosaurus

Brontosaurus Brachiosaurus
alternate name thunder lizard arm lizard
size Height – 28 feet Length – 72 to 85 feet Weight – 33,000 lbs Height – 40 feet Length – 60 to 70 feet Weight – up to 128,000 lbs
era Late Jurassic – 15.7 to 145 million years ago Late Jurassic – 16.1 to 145 million years ago
figure Long thin neck, small head, heavy body, long whip tail.
elephant like
Small head, extremely long neck, and muscular tail.
giraffe statue
limbs Front legs slightly shorter than hind legs Front legs are larger and longer than hind legs
Nare no nostrils large nostrils on the skull, between the eyes
Habitat open plains and swampy areas open plains and forests
Social Structure solitary social animals
diet eat vegetation on the ground Tall Browser – Eating Canopy
predator Adults – no predators juveniles – Allosaurus and Ceratosaurus probably only Allosaurus preyed on young, wounded or weakened animals

5 Key Differences Between Brachiosaurus and Brontosaurus

On the surface, Brachiosaurus and Brontosaurus looked very similar—both were large, tall herbivores—but they were so much more than that. Both are very large, have few predators, and both have long necks and small heads. However, despite their similarities, there are still many key differences that make it easy to differentiate the two.

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Brachiosaurus vs. Brontosaurus: Size

How Long Did Dinosaurs Live On Earth?
Brachiosaurus and Brontosaurus were among the longest and tallest dinosaurs ever


The main difference between Brachiosaurus and Brontosaurus is their size. Although both were very large dinosaurs in their own right, the former were longer and brachiosaurs were generally taller. Brontosaurus weighed 33,000 pounds and reached a height of 28 feet. However, due to their long necks and tails, they reach an incredible length of 72 to 85 feet.

Brachiosaurus, while still very long, had an advantage in height. Brachiosaurus was 60 to 70 feet long but stood 40 feet tall. They're also heavier, at an impressive 128,000 pounds. For direct comparison, the average weight of an African elephant (the heaviest living animal on Earth today) is 12,000 pounds. That means Brachiosaurus weighed more than ten African elephants!

Brachiosaurus and Brontosaurus: Limbs

Another major difference between Brontosaurus and Brachiosaurus is the length of their limbs. Brachiosaurus had longer front legs than hind legs, while Brontosaurus had shorter front legs than hind legs.

Brachiosaurus vs. Brontosaurus: Size

Thunder Dragon and Humans
Brontosaurus didn't have a neck suitable for reaching incredible heights.

© iStock.com/Aunt_Spray

As we just explained, Brachiosaurus was taller and Brontosaurus was longer, and their front legs were not the same length as their hind legs. This means they have different body shapes and postures. Since Brachiosaurus had longer forelimbs, their body naturally sloped sharply downward, whereas Brontosaurus naturally sloped slightly in the opposite direction, giving it the appearance of a hunched back. While they both have long necks and disproportionately small heads, the length of their legs and the slant of their bodies also mean they behave differently. The Brachiosaurus' neck was slightly curved in an "S" shape, and its tail was muscular. The shape of Brachiosaurus is often described as "giraffe-like".

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Brontosaurus, on the other hand, has been described as "large elephant-shaped". Brontosaurus' neck was not as high as Brachiosaurus. Instead, they stretch their necks out in front, almost parallel to the ground. Therefore, they need an extremely long tail to balance their long neck. Their tails are long and thin, tapering at the end like a whip. Scientists believe the brontosaurus was capable of flicking its tail and making a pop of more than 200 decibels — louder than a cannon.

Brachiosaurus and Brontosaurus: Nare

Brontosaurus vs Brachiosaurus - A pair of Brachiosaurus dinosaurs

© iStock.com/dottedhippo

The nostrils are huge nostrils, and in the case of brachiosaurs, the nostrils were located on the top of their heads and looked like a large lump in front of their eyes. Brontosaurus didn't have these big nostrils. It is believed that the nostrils of Brachiosaurus were located here, as the air sacs were also located under the neck. These air sacs are connected to the lung system and extend down the neck.

Brachiosaurus vs. Brontosaurus: Diet

Both Brachiosaurus and Brontosaurus were herbivores, eating a variety of plants and vegetation. However, their diets differed where they ate. Due to the physiological differences between the two dinosaurs, Brachiosaurus was a tall browser, while Brontosaurus fed on the ground. The incredible height of Brachiosaurus allowed it to feed high in the tree canopy. Therefore, Brachiosaurus usually ate plants 16 to 30 feet tall.

Brachiosaurus were so tall, they could eat trees 16 feet and above

© DariuszSankowski / pixabay – License

FAQ's (Frequently Asked Questions)

Are brachiosaurus and brontosaurus in the same family?

No, while they're both sauropods—a group of dinosaurs characterized by their long necks, small heads, long tails, thighs, and bodies—they're not in the same family. Brontosaurus belongs to the Diplodocus family, which includes some of the longest sauropods that have ever walked on Earth. At the same time, Brachiosaurus belongs to the highest Brachiosauridae .

Did brachiosaurus and brontosaurus live together?

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Yes, both Brachiosaurus and Brontosaurus lived in the same area, especially in what is now North America during the Late Jurassic. Since the exact years of their existence overlap, it's easy to assume they existed alongside each other.

Are Brachiosaurus and Brontosaurus Dangerous?

Despite their size, both Brachiosaurus and Brontosaurus were relatively quiet animals. They are both huge herbivores with few predators, which means they don't need to fight other animals. Probably the most dangerous thing is the brontosaurus' incredible tail, which is long and thin and swings with great power.

Why were Brachiosaurus and Brontosaurus called Brachiosaurus and Brontosaurus?

Brachiosaurus earned the nickname "armed lizard" because their forelimbs were longer than their hindlimbs. The reason why brontosaurus is called "thunder lizard" is because brontosaurus means thunder lizard in Greek.

How long did Brachiosaurus and Brontosaurus live?

Brachiosaurus and Brontosaurus are estimated to have lived about 100 years.

Was there a dinosaur bigger than Brachiosaurus?

Sauropods are generally considered to be the largest and heaviest dinosaurs, and Brachiosaurus was long thought to be the largest dinosaur that ever lived. However, titanosaurs such as Argentinosaurus are now thought to have surpassed Brachiosaurus in size.


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