An Ultimate Guide to Brachiosaurus: The Arm Lizard

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Name Meaning“Arm lizard”Height9.5 to 13 meters (31 – 43 ft)
PronunciationBRAK-ee-oh-sore-usLength18-22 meters (59 – 72 ft)
EraMesozoicLate JurassicWeight28.3- 46.9 metric tons (31.2-51.7 short tons)
ClassificationDinosauria,‭ Saurischia & SauropodaLocationUSA, Portugal, Tanzania, Algeria

Brachiosaurus Pictures

Computer generated image of a Brachiosaurus
Computer-generated image of a Brachiosaurus | Kitti Kahotong via iStock

The Brachiosaurus

Gage Beasley Prehistoric's Brachiosaurus Concept
Gage Beasley Prehistoric’s Brachiosaurus Concept

Typical of most dinosaurs, the Brachiosaurus, otherwise known as the Arm Lizard, existed during the Jurassic period.

More specifically, this species was said to have roamed the earth in the Late Jurassic period, about 150 million years ago. 

This creature’s first fossils were found in 1900 by Paleontologist Elmer S. Riggs and his team in the Grand River Canyon of western Colorado in America.

After Riggs discovered and analyzed the skeletons in 1903, he named it Brachiosaurus, a combination of the Greek words brachion, which means “arm,” and sauros meaning “lizard.”

This name was based on the fact that the dinosaur had longer forelimbs than hind limbs.

Other fossils were found soon after in specific locations like Tanzania, Portugal, Utah, and other areas in and around Europe and Africa. 

While later discoveries may have unseated it at the top of the list, Brachiosaurus is still considered as one the largest land animal to have ever lived
While later discoveries may have unseated it at the top of the list, Brachiosaurus is still considered one the largest land animal to have ever lived | Nobu Tamura via Wikipedia CC BY-SA 4.0

Based on these findings, the Brachiosaurus was once considered the largest dinosaur ever.

Although the discovery of other larger species, like the Argentinosaurus, has made the arm lizard lose that title, it still does not negate the fact this late Jurassic animal was a formidable creature.

Overall, the Brachiosaurus is one of the most famous dinosaur groups worldwide, and its discovery has become a focal point in the analysis and description of the prehistoric era.

Therefore, we must know more about this particular breed of dinosaurs and the unique features that set them apart from other dinosaurs that walked the earth.

Read on to discover more.

Gage Beasley's Prehistoric Shirt Collection
Gage Beasley’s Prehistoric Shirt Collection
Gage Beasley's Prehistoric Plush Collection
Gage Beasley’s Prehistoric Plush Collection

Physical Characteristics

Gage Beasley Prehistoric's Brachiosaurus Size Comparison Chart
Gage Beasley Prehistoric’s Brachiosaurus Size Comparison Chart

Paleontologists have classified the Brachiosaurus under the Sauropoda clade, which consists of four-legged, herbivorous dinosaurs with long tails and necks but small brains.

However, what distinguished this species from other sauropods was its giraffe-like appearance, possessing a very long neck and long forelimbs, which resulted in an inclined back.

Their fossils also depicted a chisel-like set of teeth (spoon-shaped), which supported its herbivorous nature, and big nasal openings at the top of its head that prove that these animals may have had a good sense of smell.

The Brachiosaurus’ skull had several holes that most likely helped reduce weight.

Reconstruction of the Felch Quarry Brachiosaurus skull
Reconstruction of the Felch Quarry Brachiosaurus skull | Etemenanki3 via Wikipedia CC BY-SA 4.0

This dinosaur’s skull was once described as high-crested, but that description was later discovered to be based on the Giraffatitan, a species once classified as Brachiosaurus before it was classified into a new genus.

Further findings have shown that the Brachiosaurus had a more camarasaurus-like skull than the high-crested one that the Giraffatitan possessed.

Plus, its front feet had two claws each, and its rear feet had three claws each.

As the long-necked dinosaur that the Brachiosaurus was, researchers speculate it may have had difficulty pumping enough oxygenated blood to its brain if its head was raised too high. However, others disagree with this.

It was also suggested that these dinosaurs were warm-blooded animals, probably having similar temperatures to humans today (35℃-38℃).

More evidence has shown that Brachiosaurus, alongside other long-necked dinosaurs (sauropods), possessed gigantotherm abilities thanks to their huge size.

The heat of their metabolism made them warm, and indicated that dinos could even reach a temperature of 45℃.

Due to their ability to achieve hot temperatures, these creatures would have had bodily or behavioral mechanisms to stay cool.

Brachiosaurus may have preferred to stay within the shade to avoid overheating
Brachiosaurus may have preferred to stay within the shade to avoid overheating | ALLVISIONN via iStock

This could have included staying in shades and maintaining a lower metabolism as adults.

The size of the Brachiosaurus is still a bone of contention because it was initially based on the B. brancai fossils, which were later reclassified as genus Giraffatitan brancai.

Paleontologist Michael Taylor finally deduced that the B. altithorax was 82 feet long.

Plus, it was concluded that it could raise its head almost 42 feet above ground level.

Still, the fossils used for this calculation weren’t full-grown dinosaurs, so there is a high chance that the Brachiosaurus could get bigger than this.

In the same vein, this species was once thought to weigh about 78 tons, although it was later disregarded as a figure obtained from an overweight model.

Further estimates later placed the Brachiosaurus between 32 and 37 tons. 

Habitat and Distribution

Researchers have argued at some point that the Brachiosaurus spent most of its time in the water because of the position of its nostrils at the top of its egg-shaped head.

This claim was refuted for several reasons.

For instance, a study showed that sauropod bodies contained pockets of air and, as a result, would float and be unstable when submerged in deep water.

Their compact feet and long limbs were also enough proof that these animals were built for walking.

Therefore, they were fully terrestrial creatures that would have preferred flat land since moving their large bodies over hilly surfaces would have been challenging.

Paleontologist Stephen Czerkas still claimed that this species possibly entered water occasionally to cool off.

Brachiosaurus may have frequented bodies of water to regulate body temperature
Brachiosaurus may have frequented bodies of water to regulate body temperature | Orla via iStock

Based on fossils obtained, it can be deduced that the Brachiosaurus inhabited North America, especially the Morrison Formation in the Southwest United States.

The Morrison Formation is well known as the area that houses several dinosaur fossils as well as other relics reminiscent of the Jurassic Period.

This area is believed to provide adequate plant life and water to sustain dinosaurs and other herbivores.

Other fossils in Africa and Europe suggest that these dinosaurs may have also lived in certain places on these continents.

Behavior and Diet

The Brachiosaurus had thick jawbones that contained a chisel-like set of teeth that supported their herbivorous nature.

Their primary diet probably consisted of cycads, ginkgoes, coniferous trees, among others.

It is also possible that adult Brachiosaurus ate up to 440-880 pounds of food daily.

Brachiosaurus consumed at an enormous amount of vegetation to maintain their massive body
Brachiosaurus consumed at an enormous amount of vegetation to maintain their massive body | CoreyFord via iStock

Due to the nature of their teeth, scientists figured that these dinosaurs did not break up huge chunks of plants but swallowed them whole instead.

They were not solitary animals and would travel together in herds in search of food.

They tended to engage in high browsing, stripping high trees of their vegetation, but would have settled for low browsing during times of low food supply.

Life Cycle

Like other sauropods, the Brachiosaurus would have laid their young ones as eggs instead of giving birth to them as live offspring.

It has been found that sauropod eggs are laid in a linear pattern rather than nests, which may indicate that female dinosaurs laid their eggs while walking. 

Other paleontologists have seen signs that long-necked dinosaurs laid eggs in regions with traces of geothermal activity.

Fossilized sauropod eggs
Fossilized sauropod eggs | Sballal via Wikipedia CC BY-SA 3.0

This might mean that sauropods incubated their offspring.

Researchers also believe that sauropods, and Brachiosaurs, by extension, did not care for their young ones.

Sauropods may have lived up to 100 years, although factors like illness, injury, and lack of food and water could have stopped some dinosaurs from living that long.

Evolution and History

The Brachiosaurus’ fossils were found in 1900 in Colorado and were eventually named Brachiosaurus in 1903 by Paleontologist  Elmer Riggs.

There are three known species of the Brachiosaurus: One is B. alataiensis which was discovered in Portugal.

The fossils obtained were parts of the limbs and hip and backbones.

In 2003, Antunes and Mateus placed this species under the new genus Lusotitan. 

Middle caudal vertebrae of Lusotitan
Middle caudal vertebrae of Lusotitan | Philip D. Mannion et al. via Wikipedia CC BY 4.0

Another notable species is the B. altithorax (Riggs, 1903), with two partial skeletons found in Utah and Colorado in the United States. In 1909, Werner Janensch unearthed the B. brancai in the Tendaguru Beds of Tanzania, Africa.

However, because this particular species did not possess some of the general features of Brachiosaurus, it was moved to a new genus, Giraffatitan.

As previously mentioned, the Morrison Formation, located in the Southwest United States, is a sedimentary rock formation that housed several fossils from the Jurassic Period—this rock formation cuts across Montana and Colorado up to New Mexico.

Since several dinosaur fossils, including the arm lizard, have been found here, the National Park Service has tagged the area as the Dinosaur National Monument.

One of the most recent finds was in 2019 when scientists unearthed a Brachiosaurus fossil in Morrison.

It was over six feet long and weighed almost 1000 pounds, and they could only pull the fossil out with the help of Clydesdale horses.

These bones were kept at the Utah Field House of Natural History State Park Museum.

Reconstructed replica of the holotype skeleton outside the Field Museum of Natural History
Reconstructed replica of the holotype skeleton outside the Field Museum of Natural History | Matt Wedel via Wikipedia CC BY 3.0

The Brachiosaurus was said to have existed in the Late Jurassic Period and reportedly saw the Cretaceous Period too.

Sources claim that these dinosaurs went into extinction after a meteor invasion on Earth.

The meteor hitting the earth caused a change in the climate, leading to the demise of some flora and fauna, including the Brachiosaurus.

Interactions with Other Species

The Brachiosaurus traveled in herds in search of food and habitat.

This habit of moving in large numbers would have discouraged predators from hunting these dinos for food.

A Brachiosaurus dinosaur herd moving through a dry desert area in the Jurassic Period of North America
A Brachiosaurus dinosaur herd moving through a dry desert area in the Jurassic Period of North America | Corey Ford via GettyImages

Their large size also made it difficult for other smaller dinosaurs and carnivores to target them as easy prey.

In addition, since the Brachiosaurus inhabited the Morrison, which was also home to other sauropod species, there would have been a case of competition for food.

Yet, since this species is known to be a high browser, unlike other dinos, they could all graze at different levels and avoid direct competition.

Cultural Significance

Brachiosaurus is one of the largest and most iconic dinosaurs worldwide.

Most depictions, however, focus on the African species B. brancai, which now belongs to its own genus, Giraffatitan.

After this dinosaur came into the limelight, it was featured as the first computer-generated dinosaur in the 1993 film Jurassic Park.

The appearance of the Brachiosaurus in this movie left the audience in awe, and the effects used were considered a ground-breaking event.

Brachiosaurus as seen in the first Jurassic Park movie
Brachiosaurus as seen in the first Jurassic Park movie | Jhayk’ Sulliy via Jurassic Park Wiki

The Brachiosaurus was also featured in other movies like Jurassic Park 3 and Walking with Dinosaurs.

It even made a cameo appearance in Walking With Monsters.

In addition, a main-belt asteroid was named 9954 Brachiosaurus in 1991 in honor of the popular genus.

Brachiosaurus fossils and replicas can also be seen in museums around the world.

Anyone visiting these places can get a glimpse of what life was like in the prehistoric age.

And as you might have guessed, discovering these fossils has helped scientists and paleontologists solve some of the mysteries surrounding this age.


The Brachiosaurus is an exciting species, which is why it is one of the most famous dinosaurs ever.

Although this creature is classified under the sauropod family, it still had its distinguishable features, like a giraffe-like appearance and long limbs, that other sauropods could not boast of.

The Brachiosaurus lived about 150 million years ago in the Late Jurassic Period when dinosaurs dominated the planet.

Gage Beasley's Brachiosaurus Stuffed Plush Toy
Gage Beasley’s Brachiosaurus Stuffed Plush Toy

And although these species were herbivorous and did not harm other creatures, they were not considered prey by the apex predators at that time due to their massive size.

Since the discovery of this dinosaur fossil, several arguments and theories have been established to understand the life pattern of the Brachiosaurus.

While some of these arguments have been resolved, several mysteries still surround one of the most enormous dinosaurs to have ever walked the earth.

Still, there is no doubt that every piece of information obtained from the remains of the Brachiosaurus has proved helpful in understanding Earth’s ancient past and has gone a long way in satisfying the curiosity of people who have always wondered what our world looked like in the prehistoric era.


Did Humans and Brachiosaurus Live Together?

Humans and Brachiosaurus did not live together.

According to researchers, humans did not appear on the earth until about 65 million years after dinosaurs went extinct.

Instead, some small mammals existed alongside dinosaurs.


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