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The difference between a Brontosaurus, a Diplodocus and a Brachiosaurus

Friday 30th September 2022
Written by: Marketing Team
long neck dinosaur

Brontosaurus, Diplodocus and Brachiosaurus are all species of Sauropod and, although this makes them very similar to each other at first glance, they are all different. Each of these magnificent creatures deserves to be celebrated for its uniqueness and we think they are all awesome – so let’s take a closer look.

What is a Sauropod?

Sauropod is a classification of large dinosaurs characterised by their long necks and tails, small heads and 4 pillar-like legs. Sauropods are all herbivores, which means they only eat plants and they are the biggest dinosaurs (and land animals) to have ever walked the earth.

The three dinosaurs we are looking at today, Brontosaurus, Diplodocus and Brachiosaurus, are some of the best known Sauropods but people often confuse them with one another and struggle to tell them apart. We’d like to change that.

Is Brontosaurus really a dinosaur?

Before we get into the differences between these incredible dinosaurs, let’s take a closer look at the elephant (or Sauropod) in the room; the Brontosaurus. While Brontosaurus is definitely a very well known kind of dinosaur, people are often confused as to whether or not it’s actually a dinosaur species in its own right or if it is actually an umbrella term for certain kinds of similar Sauropods.

“Of course it is a dinosaur, it’s a Brontosaurus!” you might be saying right now and, well, you’re not wrong. Brontosaurus is in fact a species of dinosaur in its own right, but Brontosaurus’ status as a dinosaur species has been somewhat shaky over recent years, so it’s important to clear it up.

First discovered in 1879, Brontosaurus was so similar to the Apatosaurus, discovered in 1877, that it was reclassified as a type of Apatosaurus in 1903. While Brontosaurus was still a term commonly used in popular culture throughout the 20th century, it actually wasn’t resurrected and determined to be a valid dinosaur species in its own right again until 2015.

Despite this, Brontosaurus has remained one of the best known and most loved dinosaurs of all time and is particularly popular in the USA.

With that cleared up, let’s get back to comparing these three amazing animals.

Brontosaurus vs Brachiosaurus: What’s the difference

Brontosaurus and Brachiosaurus are separate species and, yes, it is possible to tell them apart. The main difference between them is their size. Brachiosaurus is much larger and heavier than the smaller Brontosaurus, although they were both incredibly big dinosaurs.

Brontosaurus weighed around 33,000 lbs and Brachiosaurus was more than triple this weighing up to around 128,000 lbs. Surprisingly, Brontosaurus was longer than Brachiosaurus, reaching around 72-85 feet in length vs a Brachiosaurus which was around 70 feet long. With this information, we can determine that a Brontosaurus was much narrower in proportions than the stockier Brachiosaurus.

As well as being different sizes, Brontosaurus vs Brachiosaurus also stood in very different ways as they had differently shaped legs. Both dinosaurs stood on four legs, as all Sauropods do, but Brontosaurus had slightly longer hind legs and slightly shorter front legs and Brachiosaurus had longer front legs and shorter back legs.

You might be wondering why they had different leg proportions and the answer is that they ate different things! While Brontosaurus grazed at ground level, Brachiosaurus reached up into the forests to munch the treetops.

Find out more about dinosaurs in our section Lost Kingdom

Brontosaurus vs Diplodocus

While we mentioned above how famous Brontosaurus is in the USA, we’re going to compare it with the Diplodocus, which is one of the well-known dinosaurs in the UK.

Not only are Brontosaurus and Diplodocus both Sauropods but they are also both from the same family group of Sauropod; the Diplodocidae, which is a group that includes some of the longest Sauropods in the world. While both dinosaurs shared similar body shapes and both had the same general characteristics as all sauropods, Brontosaurus and Diplodocus had some key differences.

Brontosaurus and Diplodocus were both large dinosaurs but Diplodocus was longer and thinner than Brontosaurus. Diplodocus actually measured up to 175 feet in length, making it significantly longer than Brontosaurus. Despite being longer than Brontosaurus, Diplodocus was actually lighter too. Both of these amazing dinosaurs had very long tails.

Both dinosaurs ate a similar diet and swallowed small stones to help grind up the food in their digestive system – this was in place of chewing!

Despite their similarities, one of the key differences between Brontosaurus and Diplodocus is thought to be their social behaviour. While Brontosaurus is thought to be a solitary animal, Diplodocus lived in herds of between 30 – 100.

Diplodocus vs Brachiosaurus

Despite the Diplodocus and Brachiosaurus belonging to the Sauropod classification of dinosaurs, they do not belong to the same family group. While Diplodocus belongs to the Diplodocidae, which includes the longest Sauropods, Brachiosaurus belongs to the Brachiosauridae family, which includes some of the tallest Sauropods. Like the family groups would suggest, Brachiosaurus is taller than Diplodocus but Diplodocus is longer than Brachiosaurus.

Diplodocus had a long and thin whip-like tail that could crack like a whip, while Brachiosaurus had a shorter and thicker tail.

One of the most immediately apparent differences between these two large animals would be the differences in head shape. While both dinosaurs had a small head in comparison to their vast bodies, Brachiosaurus had a unique ridge above its eyes which is known as a Nare.

The Brachiosaurus’ Nare functioned in a similar way to a nose and would have had air holes in it, which the Brachiosaurus is able to breathe through. In illustrations and depictions of Brachiosaurus you can see the nare, which looks like a lump, on top of its head. This is a very quick way to know which of these two dinosaurs you are looking at.

Brontosaurus vs Brachiosaurus vs Diplodocus


Now let’s look at the differences and similarities between Brontosaurus vs Brachiosaurus vs Diplodocus and learn how to distinguish them from one another once and for all.

All three of these amazing Sauropods co-existed during the late Jurassic period on what is now North America and their remains have been discovered all over the continent. Diplodocus remains may also have been discovered in Africa!

Brontosaurus, Brachiosaurus and Diplodocus were all plant eating animals that were likely very peaceful. Once they reached maturity, these gentle giants had virtually no predators and had little cause to fight other dinosaurs. Despite being peaceful, they do all have long powerful tails. Brachiosaurus has a shorter and thicker tail that would have been incredibly strong and both Brontosaurus and Diplodocus had long thin tails that they could crack like a whip.

Brontosaurus and Diplodocus both belong to the Diplodocidae family and Brachiosaurus belongs to the taller Brachiosauridae.

These amazing dinosaurs have four strong pillar-like legs that support their massive weight, but they have slightly different proportions. Brontosaurus and Diplodocus both have longer back legs to allow for easier ground grazing and Brachiosaurus has longer front limbs for reaching up high.

Identify Brontosaurus by looking for a long and narrow solitary Sauropod with a very long tail. Scientists believe that Brontosaurus would crack its whip-like tail to make a sound that was louder than 200 decibels, which makes it louder than a cannon!

Brontosaurus is shorter than Diplodocus in length and shorter than Brachiosaurus in height.

Identify Brachiosaurus by looking for the tallest Sauropod of the three. It is also heavier and the only dinosaur of the three to have longer front limbs than its hind limbs causing its back to incline. Brachiosaurus had a shorter tail and it travelled in herds.

Brachiosaurus is instantly recognisable by the protrusion that can be seen on top of its head, also known as a nare.

Identify the Diplodocus by looking for a really really really long dinosaur. Adult Diplodocus measured up to 175 feet in length. Diplodocus moved in herds grazing on vegetation.

Diplodocus is the longest of the three dinosaurs and is actually the longest land animal that ever existed!

Now that you’ve learned about the differences between these 3 iconic sauropods, put your knowledge to the test with our amazing dinosaur quiz!

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